{"id":1771,"date":"2014-10-22T15:26:43","date_gmt":"2014-10-22T15:26:43","guid":{"rendered":"https:\/\/courses.candelalearning.com\/apvccs\/?post_type=chapter&#038;p=1771"},"modified":"2014-12-01T18:27:58","modified_gmt":"2014-12-01T18:27:58","slug":"histology-slides","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/chapter\/histology-slides\/","title":{"raw":"Slides of Histology","rendered":"Slides of Histology"},"content":{"raw":"<div class=\"bcc-box bcc-highlight\">\r\n<h3>Learning Objectives<\/h3>\r\n<ul>\r\n\t<li>Be able to describe the functions of cells commonly found in connective tissue and identify\u00a0them.<\/li>\r\n\t<li>Be able to recognize interstitial (fibrillar) collagens and elastic fibers at the light and electron microscopic\u00a0levels.<\/li>\r\n\t<li>Be able to distinguish between type I collagen, type III (reticular) collagen, and elastic\u00a0 fibers when appropriately stained material is\u00a0presented.<\/li>\r\n\t<li>Be able to use knowledge about the physical characteristics of collagen and elastin in explaining the functions of tissue where these molecules occur in large quantities (<em>e.g<\/em>., coarse type I collagen fibrils present in dense connective tissue compared to more delicate type III fibers found closer to the interface of cells and the extracellular\u00a0matrix).<\/li>\r\n\t<li>Be able to recognize different types of connective tissue (<em>e.g<\/em>., dense irregular, dense regular, loose, adipose) and provide examples where they are found in the\u00a0body.<\/li>\r\n\t<li>Be able to recognize a basement membrane (or basal lamina) in sections or micrographs where the structure is conspicuously present and understand its\u00a0functions.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<h2>LOOSE CONNECTIVE\u00a0TISSUE<\/h2>\r\nThe information below can also be accessed here:\u00a0<a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue\">http:\/\/histology.med.umich.edu\/medical\/connective-tissue<\/a>\r\n<ul>\r\n\t<li><strong>Slide 29 (small intestine, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n<\/ul>\r\nLook at the connective tissue in the\u00a0<strong>submucosa<\/strong>\u00a0which is the lighter staining area\u00a0<span style=\"text-decoration: underline;\"><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?X=-0.0322501793170344&amp;Y=-0.0796833991768999&amp;zoom=6.25&amp;navwindow=0\">[example]<\/a>\u00a0<\/span>between the intestinal epithelium and the smooth muscle layer.\u00a0 In this area note the irregular, wavy\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>\u00a0<span style=\"text-decoration: underline;\">fibers<\/span>\u00a0arranged singly or in small groups. The collagen of fibrous supporting tissues, the dermis of the skin, tendon, ligaments and bone is\u00a0<span style=\"text-decoration: underline;\">type I collagen<\/span>, which provides <span style=\"text-decoration: underline;\">tensile<\/span>\u00a0<span style=\"text-decoration: underline;\">strength<\/span>. The background will be clear, reflecting a \u201cground substance\u201d-rich connective tissue.\u00a0 Look for elongated nuclei, usually solitary, from which a modest amount of tapered cytoplasm extends from either one or both poles of the nucleus.\u00a0 These are\u00a0<span style=\"text-decoration: underline;\">fibroblasts<\/span>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?X=-0.00192121376500704&amp;Y=-0.100094632273563&amp;Zoom=100.0\">[example]<\/a>(as opposed to clusters of similar appearing elongate nuclei that are usually smooth muscle cells or Schwann cells in a nerve that you will learn to recognize soon).\u00a0 Note that the nucleoplasm of a fibroblast has a generally fine stippled (dot-like) chromatin pattern with occasional coarse chromatin clumps (heterochomatin) and one or two nucleoli.\u00a0 Look for more examples of fibroblasts and note that you rarely see much cytoplasm and that the nuclei of these cells can be quite condensed and hyperchromatic depending upon the plane of section or the metabolic state.\u00a0 You should be able to recognize a range of nuclear morphologies and be able to identify the cells as fibroblasts.\u00a0Most of the rounded cells you may see in the submucosa are likely white blood cells (monocytes, macrophages, and occasional neutrophils) that have migrated out into the\u00a0tissue.\r\n\r\nNow look at the region\u00a0<strong>immediately underneath the intestinal epithelium\u00a0<\/strong><em>(<\/em>which is called the\u00a0<strong><em>lamina\u00a0<\/em><\/strong><strong><em>propria<\/em><\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?X=0.0247596915263671&amp;Y=0.0434149522694053&amp;zoom=50&amp;navwindow=0\">[example]<\/a>).\u00a0 This region is also a\u00a0<strong>loose, irregular connective tissue<\/strong>\u00a0but can be so extensively infiltrated by white blood cells and\u00a0<span style=\"text-decoration: underline;\">plasma<\/span>\u00a0<span style=\"text-decoration: underline;\">cells<\/span>\u00a0that the supporting fibers and ground substance are obscured.\u00a0\u00a0<span style=\"text-decoration: underline;\">Neutrophils<\/span>\u00a0and\u00a0<span style=\"text-decoration: underline;\">macrophages<\/span>\u00a0are also present and both are discussed\u00a0below.\r\n<h3><strong>Plasma\u00a0Cells<\/strong><\/h3>\r\n<ul>\r\n\t<li><strong>Slide 29 (small intestine, H&amp;E)\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n\t<li><strong>Slide 40 (trachea, H&amp;E)\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n<\/ul>\r\nLook for plasma cells within the\u00a0<strong>lamina propria<\/strong>\u00a0of\u00a0<strong>slide\u00a0<\/strong><strong>29<\/strong>\u00a0<span style=\"text-decoration: underline;\"><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?X=0.0247596915263671&amp;Y=0.0434149522694053&amp;zoom=50&amp;navwindow=0\">[example]<\/a><\/span>. \u00a0They are round to oval shaped cells with a distinct cell boundary and a nucleus set to one side.\u00a0 Note the coarse chromatin clumps organzed as radial spokes in the round nuclei which is therefore often described as having a \u201cclockface\u201d or \u201cwagon-wheel\u201d appearance.\u00a0 You should note that the cytoplasm is quite basophilic (i.e. \u201cbase loving\u201d so it binds hematoxylin and stains dark blue\/purple), and, in well fixed tissue, the cytoplasm in many of the plasma cells is frequently granular (the rough endoplasmic reticulum, really) rather than smooth or even in\u00a0appearance.\r\n\r\nFind the\u00a0<span style=\"text-decoration: underline;\">Golgi<\/span>\u00a0<span style=\"text-decoration: underline;\">complex<\/span>, a pale or slightly eosinophilic (=eosin \u201cloving\u201d, an area rich in membranes containing basic amino acids, syn. = acidophilic) region adjacent to the cell nucleus.\u00a0 The Golgi complex in these particular plasma cells is usually in the form of a fine crescent adjacent to the nucleus and it takes some practice to\u00a0recognize.\r\n\r\nRecall that the primary function of plasma cells is antibody secretion, so they are a prominent constituent of loose connective tissue wherever antigens may enter the body, such as the <strong>gastrointestinal, urogenital, and respiratory tracts<\/strong>. Plasma cells may also be found\u00a0<strong>within the connective tissue<\/strong>\u00a0of many of the\u00a0<strong>glands<\/strong>\u00a0that secrete into these regions. An excellent example of this is\u00a0<strong>slide 40<\/strong>\u00a0from the trachea (part of the respiratory tract). Look at the areas outlined in the\u00a0<a href=\"http:\/\/www.med.umich.edu\/histology\/cellsTissue\/slide40orientation.jpg\">orientation diagram of the trachea<\/a>\u00a0and locate the loose, cellular connective tissue within the glands (the \u201cglands\u201d are coiled tubes of columnar epithelial cells; some the epithelial cells are tall and eosinophilic, whereas others are shorter and more basophilic). In addition to some fibroblasts and a few delicate collagen fibers, you should see quite a few plasma cells<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/view.apml?X=-0.289979608430315&amp;Y=-0.0947460070480663\">[example]<\/a>\u00a0amongst the epithelial\u00a0tubes.\r\n\r\n<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/view.apml?X=-0.219785216592467&amp;Y=0.00469172775183228&amp;Zoom=12.5\"><strong>Slide 40<\/strong><\/a>\u00a0is also a very good specimen to examine the pseudostratified, ciliated columnar epithelium of the trachea. Note also that the\u00a0<span style=\"text-decoration: underline;\">basement<\/span>\u00a0<span style=\"text-decoration: underline;\">membrane<\/span>\u00a0underlying this particular epithelium is especially prominent.\u00a0<span style=\"text-decoration: underline;\">Type IV<\/span>\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>, which does not form fibrils, but rather a fine meshwork, is present in all basement membranes. The basal lamina is anchored to the underlying connective tissue by fine fibrils of\u00a0<span style=\"text-decoration: underline;\">type VII<\/span>\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>\u00a0(you obviously can\u2019t tell this looking at it in the light microscope, but you should recall this from\u00a0lecture).\r\n<h3><strong>Neutrophils<\/strong><\/h3>\r\n<ul>\r\n\t<li><strong>Slide 29 (small intestine, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n<\/ul>\r\nLook in the lamina propria amongst the plasma cells and you will find neutrophils<span style=\"text-decoration: underline;\">\u00a0<\/span>that have emigrated from the bloodstream into the tissue space as part of the immune response.\u00a0 Neutrophils can be identified by their granular cytoplasm and their multilobular, condensed nuclei.\u00a0 Because of their nuclear morphology, they are frequently also called \u201c<span style=\"text-decoration: underline;\">polymorphonuclear leukocytes<\/span>\u201d (aka \u201cPMNs\u201d or \u201c<span style=\"text-decoration: underline;\">polys<\/span>\u201d).\u00a0 Neutrophils generally enter tissues in large numbers only in response to a disease stimulus.\u00a0\u00a0 However, as seen in this slide, it is quite normal to find them in tissues such as the gut where foreign substances frequently invoke an inflammatory response.\u00a0 You will study neutrophils in much greater detail in other sequences and in your histopathology course, but it is useful for now to at least be able to recognize them in various tissues and\u00a0organs.\r\n<h3><strong>Macrophages<\/strong><\/h3>\r\n<ul>\r\n\t<li><strong>Slide 26 (lymph node, H&amp;E)\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/026_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/026_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n<\/ul>\r\nWith low power, locate the\u00a0<strong>medulla<\/strong>\u00a0(the interior) of the lymph node.\u00a0 Look for a region characterized by interlacing cords of cells.\u00a0<span style=\"text-decoration: underline;\">Macrophages<\/span>\u00a0are the biggest, rounded cells that are floating free in the spaces between the cords of cells.\u00a0 Many of the free cells in these medullary sinuses cannot be identified; however, the large rounded cells, with eccentrically placed, vesicular nuclei are the ones you should try to\u00a0find.\r\n\r\n<em>Many of these macrophages contain phagocytosed red blood cells or the brownish breakdown pigment, hemosiderin (which is the result of lysosomal action on the ingested red blood cells.)<\/em>.\u00a0 Be sure you can identify a macrophage and not just a bunch of cells superimposed upon one another.\u00a0 Macrophages can be seen also in the\u00a0<strong>subcapsular\u00a0<\/strong><strong>sinus<\/strong>\u00a0(the lighter staining area just under the capsule at the periphery of the lymph\u00a0node).\r\n\r\nThe \u201cmononuclear phagocyte system\u201d (also called the \u201creticuloendothelial system\u201d for historic reasons) consists of free and fixed macrophages throughout the body.\u00a0 These cells are important in removing all kinds of debris from the body as well as playing a major role in the immune\u00a0response.\r\n<h3><strong>Fat\u00a0Cells<\/strong><\/h3>\r\n<ul>\r\n\t<li><strong>Slide 152 (pharynx, H&amp;E)<\/strong><strong>\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Digestive%20System\/Pharynx%20Esophagus%20and%20Stomach\/152_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Digestive%20System\/Pharynx%20Esophagus%20and%20Stomach\/152_HISTO_40X.svs\/is.sis?X=0&amp;Y=0&amp;zoom=1.29654335961189&amp;chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n\t<li><strong>Slide 30 (mesentery, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/030_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/030_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n\t<li><strong>Slide H2 (fetal thorax, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/WesternUniv\/H2.svs\/view.apml?X=0&amp;Y=0&amp;zoom=2.1344377190188\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/WesternUniv\/H2.svs\/is.sis?X=0&amp;Y=0&amp;zoom=2.1344377190188&amp;chost=141.214.65.171\">ImageScope<\/a>\u00a0(virtual slide courtesy of Western\u00a0University)<\/li>\r\n<\/ul>\r\n<strong>Slide 152\u00a0<\/strong>is a section from the pharynx.\u00a0\u00a0 \u00a0Locate the\u00a0<strong>large clear\u00a0<\/strong>circles\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/152_HISTO_20X.svs\/view.apml?X=0.0146807193849723&amp;Y=0.00803494799636945&amp;Zoom=25.0\">[example]<\/a>\u00a0in the connective tissue that sits beneath the epithelium.\u00a0 These are\u00a0<span style=\"text-decoration: underline;\">fat<\/span>\u00a0<span style=\"text-decoration: underline;\">cells<\/span>\u00a0(or\u00a0<span style=\"text-decoration: underline;\">adipocytes<\/span>).\u00a0 In white or unilocular adipose tissue, lipids are stored as a single, non-membrane bound droplet in these cells.\u00a0 A fatty tissue called brown or multilocular fat, produced during fetal development, has adipocytes that contain\u00a0<strong>multiple<\/strong>\u00a0fat droplets. Brown fat is important for thermoregulation in newborns and hibernating mammals. In humans, brown fat is widely distributed throughout the body in the first decade of life, but it then disappears except for regions around the kidney, suprarenal glands, aorta, neck and mediastinum. None of our slides of adult tissue shows any brown fat, however this rather unique tissue can be seen in\u00a0<strong>slide\u00a0<\/strong><strong>H2<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/WesternUniv\/H2.svs\/view.apml?X=-0.243351315111056&amp;Y=0.147051200010625&amp;zoom=50\">[example]<\/a>, which is from a developing\u00a0fetus.\r\n\r\nLook for\u00a0<span style=\"text-decoration: underline;\">adipose<\/span>\u00a0<span style=\"text-decoration: underline;\">tissue<\/span>\u00a0in\u00a0<strong>Slide #30<\/strong>\u00a0which is taken from abdominal mesentery (the connective tissue that suspends the viscera within the abdominal cavity). Some of the individual fat cells are often broken during tissue preparation, but the overall impression of what the tissue looks like is the important\u00a0point.\r\n<h3><strong>Mast\u00a0Cells<\/strong><\/h3>\r\n<ul>\r\n\t<li><strong>Slide 160<\/strong>\u00a0<strong>(stomach, PAS\u00a0&amp;\u00a0Azure II)<\/strong><strong>\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/160_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/160_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n<\/ul>\r\nMast cells can only be definitively recognized with special stains such as\u00a0<strong>Azure II<\/strong>\u00a0and\u00a0<strong>toluoidine blue<\/strong>\u00a0that identify the heparin storage granules (Azure metachromatically stains the heparin purple). Mast cells are most abundant in the connective tissue associated with the lining of the digestive and respiratory systems, and your collection just so happens to contain a tissue section from the stomach that has been stained with PAS and Azure II. As you look at this section, you will see a very obvious layer of mucous epithelial cells (PAS also reacts with the carbohydrate-rich mucin). However, to see the mast cells, you will need to look deeper in the<strong>\u00a0submucosa<\/strong>where you should find small, ovoid cells amongst the collagen fibers with spherical, eccentric nuclei and\u00a0<strong>intensely basophilic<\/strong>\u00a0(dark purple to black)<strong>\u00a0granules<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/160_HISTO_40X.svs\/view.apml?X=-0.237010226729416&amp;Y=0.179379468459487&amp;zoom=100\">[example]<\/a>. The granules are often so dark that they obscure the\u00a0nucleus.\r\n<h2>Reticular\u00a0tissue<\/h2>\r\n<ul>\r\n\t<li><strong>Slide 27 (lymph node, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/027_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/027_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n\t<li><strong>Slide 28 (lymph node, silver stain)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/028-2_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/028-2_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n<\/ul>\r\nThe fine collagenous network that provides support in the bone marrow, lymphatic organs, around individual smooth muscle cells, and beneath most epithelia is composed mainly of Type III collagen. The collagen has an associated carbohydrate moiety (uncharacterized) that can reduce Ag+ to metallic Ag revealing a network (reticulum) of fine, black fibrils. These are termed reticular (or rarely, argyrophilic= \u201csilver loving\u201d) fibers. On\u00a0<strong>slide #27<\/strong>\u00a0look at the accumulations of<strong>darkly stained cells<\/strong>\u00a0(lymphocytes in a lymph node). Note at high power that fibrils or fibers of any type cannot be readily observed. Now with\u00a0<strong>slide #28<\/strong>\u00a0(make sure your slide is stained with silver; it should say \u201cAg\u201d on the label!), note how a network of\u00a0<strong>fine black fibrils<\/strong>\u00a0is present in this same tissue following silver staining. These are reticular fibers, found in skin, muscle and blood vessels. The reticular fibers provide physical support for all the cells present in tissues subject to stretching. You are not responsible for recognizing reticular fibers unless a silver stain is\u00a0used.\r\n\r\nPlease remember that virtually all cells (except for those in the brain and spinal cord) are provided with some degree of support by collagen (reticular fibers) even though that may not be apparent with H&amp;E staining. (Masson Trichrome and silver staining are frequently used in pathology to determine if connective tissue has proliferated\u2013a sign of damage and attempted repair\u2013in the liver, kidney and\u00a0lung.)\r\n<h2><strong>DENSE CONNECTIVE\u00a0TISSUE<\/strong><\/h2>\r\n<h3><strong>DENSE IRREGULAR CONNECTIVE\u00a0TISSUE<\/strong><\/h3>\r\n<ul>\r\n\t<li><strong>Slide 33 (skin, Verhoeff stain)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/033_HISTO_20X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/033_HISTO_20X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n\t<li><strong>Slide 250-1<\/strong>\u00a0<strong>(vagina, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/250-1_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/250-1_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n\t<li><strong>Slide 250-2<\/strong>\u00a0<strong>(vagina, trichrome)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Female%20Reproductive%20System\/250-2_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Female%20Reproductive%20System\/250-2_HISTO_40Xsvs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n<\/ul>\r\nThe area beneath the stratified squamous epithelium shown in\u00a0<strong>slide 33<\/strong>\u00a0is the\u00a0<span style=\"text-decoration: underline;\">dermis<\/span>, which is composed of dense irregular connective tissue.\u00a0 In this section, the fibers clearly predominate.\u00a0 This slide has been stained with iron hematoxylin and eosin so you can see\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>\u00a0<span style=\"text-decoration: underline;\">fibers<\/span>(orange) as well as elastic fibers (purple\/black) in the dermis\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/033_HISTO_20X.svs\/view.apml?X=0.0461274926182096&amp;Y=-0.275428605243772&amp;zoom=50&amp;navwindow=0\">[example]<\/a>.\u00a0Note how the diameter of the fibers varies with location.\u00a0 In the region immediately beneath the epidermis you can see how the elastic fibers are interconnected forming an elaborate,\u00a0<strong>delicate<\/strong>\u00a0net of fibers\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/033_HISTO_20X.svs\/view.apml?X=-0.115515340016333&amp;Y=-0.38113644185685&amp;zoom=100&amp;navwindow=0\">[example]<\/a>amongst thin strands of collagen. However, deeper in the dermis, the collagen and elastic fibers are much\u00a0thicker.\r\n\r\n<strong>Slide 250<\/strong>\u00a0which you used to look at stratified squamous non-keratinizing epithelium is also useful for the study of connective tissue (we will also use this slide to study smooth muscle and peripheral ganglia).\u00a0 Be sure you look at both the\u00a0<strong>H&amp;E<\/strong>\u00a0and\u00a0<strong>Masson trichrome-stained<\/strong>\u00a0slides as they provide an excellent opportunity to see how\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>\u00a0stains in connective tissue when either stain is applied.\u00a0 When we study smooth muscle and peripheral nerve tissue we will come back to this slide to try and distinguish between collagen fibers and fascicles of smooth muscle and\/or nerve fibers and\u00a0ganglia.\r\n\r\n<strong>NOTE:<\/strong>\u00a0\u00a0<strong>Slide 250<\/strong>\u00a0illustrates a point about the limits of classification schemes. Even though we try to set up rigid categories (e.g. \u201cloose\u201d versus \u201cdense\u201d connective tissue), sometimes it is not always possible to classify connective tissue in a given section; it may be a little loose, a little dense, a little fatty, etc. In these particular instances, don\u2019t worry so much about trying to\u00a0<strong>exactly classify<\/strong>\u00a0the tissue per se, but at least try to identify the cellular and extracelluar components that you can (also bear in mind that you can\u2019t always definitely identify<strong>\u00a0every\u00a0<\/strong>cell) and think how its overall appearance reflects its\u00a0<strong>function<\/strong>.\r\n<h3><strong>DENSE REGULAR CONNECTIVE\u00a0TISSUE<\/strong><\/h3>\r\n<h4><strong>Collagenous<\/strong><\/h4>\r\n<ul>\r\n\t<li><strong>Slide 106<\/strong>\u00a0<strong>(plantar skin and tendon, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/106_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/106_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n\t<li><strong>Slide 112 (plantar skin and tendon, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Integumentary%20System\/112_HISTO_40X.svs\/view.apml?X=0&amp;Y=0&amp;zoom=1.6670216542421\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Integumentary%20System\/112_HISTO_40X.svs\/is.sis?X=0&amp;Y=0&amp;zoom=1.6670216542421&amp;chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n<\/ul>\r\n<strong>Slide 106<\/strong>\u00a0and\u00a0<strong>112\u00a0<\/strong>have bits of well preserved flexor tendon at the top of the section (the tissue at the\u00a0<strong>very top<\/strong>\u00a0of slide 112 is actually skeletal muscle -which you\u2019ll study in the next lab; the tendon is just below it).\u00a0 Note the\u00a0<strong>regular orientation<\/strong>\u00a0of the collagen fibers (there\u2019s a bit a \u201cwaviness\u201d but you should get the idea). You should also observe that there aren\u2019t a lot of cells, a characteristic of \u201cdense\u201d connective tissue. The very small cracks between the fibers are just artifacts of shrinkage that occured during tissue preparation. Of course, there are some places where there are breaks in the dense regular connective tissue of the tendon containing loose connective tissue associated with nerves and blood vessels or the occasional bit of adipose\u00a0tissue.\r\n<h4><strong>Elastic\u00a0tissue<\/strong><\/h4>\r\n<ul>\r\n\t<li><strong>slide 36 (Aorta, aldehyde fuchsin)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/036_HISTO_20X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/036_HISTO_20X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n\t<li><strong>slide 88 (Aorta, H&amp;E)\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/088_HISTO_20X.svs\/view.apml?width=953&amp;height=1025\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/088_HISTO_20X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\r\n<\/ul>\r\nThese slides are examples of regularly arranged sheets (<span style=\"text-decoration: underline;\">lamellae<\/span>) of\u00a0<span style=\"text-decoration: underline;\">elastin<\/span>.\u00a0\u00a0<strong>Slide 36<\/strong>\u00a0is stained with aldehyde fuchsin and Masson trichrome (Aldehyde Fuchsin, Fe. Hem.\u00a0&amp;\u00a0Mass.), so the elastic lamellae are\u00a0<strong>purple<\/strong>.\u00a0<strong>Slide 88<\/strong>\u00a0is stained with H&amp;E where the concentric rings of elastic lamellae are intensely stained with eosin giving a\u00a0<strong>glassy red\u00a0<\/strong><strong>appearance<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/088_HISTO_20X.svs\/view.apml?X=0.0849156577983365&amp;Y=0.131259364204137&amp;zoom=50\">[example]<\/a>\u00a0(one of the few places where elastin is easy to recognize in H&amp;E\u00a0sections).\r\n\r\nTwo other locations where elastic fibers can be readily seen in H&amp;E sections are in the lamina propria of the pharynx (<strong>slide 152<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Digestive%20System\/Pharynx%20Esophagus%20and%20Stomach\/152_HISTO_40X.svs\/view.apml?X=0.276980887872605&amp;Y=0.240060695222288&amp;zoom=25\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Digestive%20System\/Pharynx%20Esophagus%20and%20Stomach\/152_HISTO_40X.svs\/is.sis?X=0.276980887872605&amp;Y=0.240060695222288&amp;zoom=25&amp;chost=141.214.65.171\">ImageScope<\/a>) and the trachea (<strong>slide 40\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/view.apml?\">WebScope<\/a><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/is.sis?X=-0.280059541325328&amp;Y=0.0776299677933251&amp;Zoom=37.5&amp;chost=141.214.65.171\">ImageScope<\/a>).\u00a0<em>Unlike the tissue of the aorta which would be classified as \u201cregular,\u201d these tissues are obviously\u00a0<strong>irregular<\/strong>\u00a0but they\u2019re mentioned here for the purpose of illustrating how aggregates of elastic fibers appear in H&amp;E-stained sections.<\/em>\u00a0Just as in the H&amp;E-stained aorta, the elastic fibers in the pharynx and trachea are glassy and orange-red \u2013they appear as stippled dots because they\u2019ve been cut in cross\u00a0section.\r\n<div>\r\n<div>\r\n<h2>Electron\u00a0Micrographs<\/h2>\r\n<\/div>\r\n<div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>26 Connective Tissue - Dense Irregular\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/026%20-%20Connective%20tissue_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/026%20-%20Connective%20tissue_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nDense Connective Tissue. Note the alternating layers of fibroblasts and collagenous fiber bundles. Make sure you can see the difference between cross sectioned and longitudinally sectioned collagenous fibrils. In dense connective tissue, which type of cell is most common? (CT7)\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>18 Loose Connective Tissue - Lamina propria of tracheal mucosa\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/018%20-%20Connective%20tissue_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/018%20-%20Connective%20tissue_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nLoose Connective Tissue. In this micrograph of loose connective tissue of the tracheal mucosa numerous (labeled) cells of the connective tissue are present. Note the relative size of the different cell types, their shapes, amount of rough ER and variously sized granules and inclusions. Then use your text and atlas to review the diagnostic features of each connective tissue cell present in the micrograph. Note the paucity of collagen fibrils. What was present in the \"empty\" looking intercellular space? (CT10)\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>27 Elastic Connective Tissue - Junction of Media and Adventilia of artery\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/027%20-%20Elastic%20tissue_001.svs\/view.apml\">Webscope<\/a> <a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/027%20-%20Elastic%20tissue_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nObserve the branching nature of the elastic fiber and the \"mantle\" of elastic microfibrils. The cross banding of the collagenous fibrils is easily observed.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>28 Collagen and Elastin - Cross section of Chorda Tendinea\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/028%20-%20Collagen%20&amp;%20elastin_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/028%20-%20Collagen%20&amp;%20elastin_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nObserve the mixture of collagen and elastic fibers in this cross section of chorda tendinea. Although collagen fibers mostly fill the view, there are numerous elastic fibers, which provide the elasticity essential for the function of the tissue.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>29 Tendon - Longitudinal section\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/029%20-%20Tendon_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/029%20-%20Tendon_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nNote the uniform distribution of regularly arranged collagen fibers (type I).\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>25 Connective Tissue - Fibroblast\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/025%20-%20Fibroblast_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/025%20-%20Fibroblast_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nObserve the large amount of rough endoplasmic reticulum (ER) in these cells. Is this an indication of an active or inactive cell? (CT9) Test your ability to identify different organelles at this magnification!\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>20 Mast cell - Human\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/020%20-%20Mast%20cell_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/020%20-%20Mast%20cell_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nMast cells contain a mixture of granule types reflective of the variety of substances they secrete. Histamine and heparin are found in the more \"regular\" looking granules (evenly dark and round). Other secretory products include leukotrienes and other phospholipid derivatives, which are made from the sheets of membranes arranged as lamella, whorls, or even scroll-like bodies within the more irregular appearing granules. What are the secretory products of the mast cell? (CT11)\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>63 Macrophage\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/063%20-%20Macrophage_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/063%20-%20Macrophage_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nTissue macrophages can be found in many different organs. As they have a phagocytic function, removing pathogens and cell debris, macrophages usually contain abundant primary and secondary lysosomes.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>21 Plasma cell\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/021%20-%20Plasma%20cell_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/021%20-%20Plasma%20cell_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nThis electron micrograph shows a typical secretory cell, a plasma cell, which secretes immunoglobulin protein. Many of the major types of cellular organelles are visible in this image. In the nucleus, areas of euchromatin and heterochromatin can easily be identified. Use these micrographs to review the structure of organelles. Be sure you recognise favourable sections of the nucleas, mitochondria, and rough ER.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<ul>\r\n\t<li><strong>23 Fat Cells - Mature\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/023%20-%20Fat%20cells_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/023%20-%20Fat%20cells_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\nThis electron micrograph depicts mature fat cells. You can see one large lipid droplet in the cytoplasm of each cell. The nuclei of many cells are not included in the field of view. Brown fat cells would have several small lipid droplets all of which would be roughly the same size. Remember that each fat cell is enclosed by a thin basal lamina (Unfortunately, in these examples you can\u2019t see the basal lamina). Where are the nuclei of the fat cells? (CT8)\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<h3>Review Questions<\/h3>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>1. What type of epithelium lines the luminal surface of the\u00a0intestine?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0The luminal surface of the intestine is made up of a simple columnar\u00a0epithelium.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>2. Why is rough endoplasmic reticulum\u00a0basophilic?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0The ribosomes attached to rough ER are associated with both ribosomal and messenger RNA - these nucleic acids carry a net negative charge and bind basic dyes (which are positively\u00a0charged).<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>3. What type of lining epithelium is present in the\u00a0pharynx?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Stratified squamous non-keratinizing epithelium lines the\u00a0pharynx.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>4. Can you see a nucleus in each fat\u00a0cell?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0No, because not all nuclei are on the plane of\u00a0section.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>5. What do mast cells\u00a0do?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Mast cells are actively involved in a host\u2019s immune response and produce many substances, some of which are heparin and histamine. The degranulation of these cells is responsible for triggering type I, immediate hypersensitivity reactions. Type I reactions, also called anaphylactic reactions, are something you will learn about while studying the immune system later on, but for now, here is a quick explanation. IgE is an antibody, produced by plasma cells, that has a high affinity for mast cells and basophils. The antibody binds mast cells and waits for a second exposure to whatever it happens to be responsive to (an allergen). When the IgE binds an appropriate molecule, it will trigger degranulation of the mast cell and the vasodilation, congestion, bronchiolar constriction, wheezing, etc. associated with allergies and other type I\u00a0reactions<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>6. Why do cells actively secreting proteins exhibit basophilic\u00a0cytoplasm?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Protein secreting cells have a basophilic cytoplasm because they are full of rough ER, which stains with hematoxylin, a basic\u00a0dye.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>7. In dense connective tissue, which type of cell is most\u00a0common?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Dense connective tissue is full of\u00a0fibroblasts.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>8. Where are the nuclei of fat\u00a0cells?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Fat cell nuclei are on the periphery of the cell and may or may not be in the plane of\u00a0section.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>9. Is rough ER an indication of an active or an inactive\u00a0cell?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Large amounts of rough ER indicate that the cell is active and is producing large amounts of\u00a0proteins.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>10. What was present in the \u201cempty\u201d looking intercellular\u00a0space?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0The empty space within connective tissue is ground\u00a0substance.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<div>11. What are the secretory products of the mast\u00a0cell?<\/div>\r\n<\/div>\r\n<div style=\"line-height: 1.5em;\">\r\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Heparin and histamine are just some of the contents of mast cell\u00a0granules.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n\r\nhttps:\/\/oea.herokuapp.com\/assessments\/401","rendered":"<div class=\"bcc-box bcc-highlight\">\n<h3>Learning Objectives<\/h3>\n<ul>\n<li>Be able to describe the functions of cells commonly found in connective tissue and identify\u00a0them.<\/li>\n<li>Be able to recognize interstitial (fibrillar) collagens and elastic fibers at the light and electron microscopic\u00a0levels.<\/li>\n<li>Be able to distinguish between type I collagen, type III (reticular) collagen, and elastic\u00a0 fibers when appropriately stained material is\u00a0presented.<\/li>\n<li>Be able to use knowledge about the physical characteristics of collagen and elastin in explaining the functions of tissue where these molecules occur in large quantities (<em>e.g<\/em>., coarse type I collagen fibrils present in dense connective tissue compared to more delicate type III fibers found closer to the interface of cells and the extracellular\u00a0matrix).<\/li>\n<li>Be able to recognize different types of connective tissue (<em>e.g<\/em>., dense irregular, dense regular, loose, adipose) and provide examples where they are found in the\u00a0body.<\/li>\n<li>Be able to recognize a basement membrane (or basal lamina) in sections or micrographs where the structure is conspicuously present and understand its\u00a0functions.<\/li>\n<\/ul>\n<\/div>\n<h2>LOOSE CONNECTIVE\u00a0TISSUE<\/h2>\n<p>The information below can also be accessed here:\u00a0<a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue\">http:\/\/histology.med.umich.edu\/medical\/connective-tissue<\/a><\/p>\n<ul>\n<li><strong>Slide 29 (small intestine, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<\/ul>\n<p>Look at the connective tissue in the\u00a0<strong>submucosa<\/strong>\u00a0which is the lighter staining area\u00a0<span style=\"text-decoration: underline;\"><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?X=-0.0322501793170344&amp;Y=-0.0796833991768999&amp;zoom=6.25&amp;navwindow=0\">[example]<\/a>\u00a0<\/span>between the intestinal epithelium and the smooth muscle layer.\u00a0 In this area note the irregular, wavy\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>\u00a0<span style=\"text-decoration: underline;\">fibers<\/span>\u00a0arranged singly or in small groups. The collagen of fibrous supporting tissues, the dermis of the skin, tendon, ligaments and bone is\u00a0<span style=\"text-decoration: underline;\">type I collagen<\/span>, which provides <span style=\"text-decoration: underline;\">tensile<\/span>\u00a0<span style=\"text-decoration: underline;\">strength<\/span>. The background will be clear, reflecting a \u201cground substance\u201d-rich connective tissue.\u00a0 Look for elongated nuclei, usually solitary, from which a modest amount of tapered cytoplasm extends from either one or both poles of the nucleus.\u00a0 These are\u00a0<span style=\"text-decoration: underline;\">fibroblasts<\/span>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?X=-0.00192121376500704&amp;Y=-0.100094632273563&amp;Zoom=100.0\">[example]<\/a>(as opposed to clusters of similar appearing elongate nuclei that are usually smooth muscle cells or Schwann cells in a nerve that you will learn to recognize soon).\u00a0 Note that the nucleoplasm of a fibroblast has a generally fine stippled (dot-like) chromatin pattern with occasional coarse chromatin clumps (heterochomatin) and one or two nucleoli.\u00a0 Look for more examples of fibroblasts and note that you rarely see much cytoplasm and that the nuclei of these cells can be quite condensed and hyperchromatic depending upon the plane of section or the metabolic state.\u00a0 You should be able to recognize a range of nuclear morphologies and be able to identify the cells as fibroblasts.\u00a0Most of the rounded cells you may see in the submucosa are likely white blood cells (monocytes, macrophages, and occasional neutrophils) that have migrated out into the\u00a0tissue.<\/p>\n<p>Now look at the region\u00a0<strong>immediately underneath the intestinal epithelium\u00a0<\/strong><em>(<\/em>which is called the\u00a0<strong><em>lamina\u00a0<\/em><\/strong><strong><em>propria<\/em><\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?X=0.0247596915263671&amp;Y=0.0434149522694053&amp;zoom=50&amp;navwindow=0\">[example]<\/a>).\u00a0 This region is also a\u00a0<strong>loose, irregular connective tissue<\/strong>\u00a0but can be so extensively infiltrated by white blood cells and\u00a0<span style=\"text-decoration: underline;\">plasma<\/span>\u00a0<span style=\"text-decoration: underline;\">cells<\/span>\u00a0that the supporting fibers and ground substance are obscured.\u00a0\u00a0<span style=\"text-decoration: underline;\">Neutrophils<\/span>\u00a0and\u00a0<span style=\"text-decoration: underline;\">macrophages<\/span>\u00a0are also present and both are discussed\u00a0below.<\/p>\n<h3><strong>Plasma\u00a0Cells<\/strong><\/h3>\n<ul>\n<li><strong>Slide 29 (small intestine, H&amp;E)\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<li><strong>Slide 40 (trachea, H&amp;E)\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<\/ul>\n<p>Look for plasma cells within the\u00a0<strong>lamina propria<\/strong>\u00a0of\u00a0<strong>slide\u00a0<\/strong><strong>29<\/strong>\u00a0<span style=\"text-decoration: underline;\"><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml?X=0.0247596915263671&amp;Y=0.0434149522694053&amp;zoom=50&amp;navwindow=0\">[example]<\/a><\/span>. \u00a0They are round to oval shaped cells with a distinct cell boundary and a nucleus set to one side.\u00a0 Note the coarse chromatin clumps organzed as radial spokes in the round nuclei which is therefore often described as having a \u201cclockface\u201d or \u201cwagon-wheel\u201d appearance.\u00a0 You should note that the cytoplasm is quite basophilic (i.e. \u201cbase loving\u201d so it binds hematoxylin and stains dark blue\/purple), and, in well fixed tissue, the cytoplasm in many of the plasma cells is frequently granular (the rough endoplasmic reticulum, really) rather than smooth or even in\u00a0appearance.<\/p>\n<p>Find the\u00a0<span style=\"text-decoration: underline;\">Golgi<\/span>\u00a0<span style=\"text-decoration: underline;\">complex<\/span>, a pale or slightly eosinophilic (=eosin \u201cloving\u201d, an area rich in membranes containing basic amino acids, syn. = acidophilic) region adjacent to the cell nucleus.\u00a0 The Golgi complex in these particular plasma cells is usually in the form of a fine crescent adjacent to the nucleus and it takes some practice to\u00a0recognize.<\/p>\n<p>Recall that the primary function of plasma cells is antibody secretion, so they are a prominent constituent of loose connective tissue wherever antigens may enter the body, such as the <strong>gastrointestinal, urogenital, and respiratory tracts<\/strong>. Plasma cells may also be found\u00a0<strong>within the connective tissue<\/strong>\u00a0of many of the\u00a0<strong>glands<\/strong>\u00a0that secrete into these regions. An excellent example of this is\u00a0<strong>slide 40<\/strong>\u00a0from the trachea (part of the respiratory tract). Look at the areas outlined in the\u00a0<a href=\"http:\/\/www.med.umich.edu\/histology\/cellsTissue\/slide40orientation.jpg\">orientation diagram of the trachea<\/a>\u00a0and locate the loose, cellular connective tissue within the glands (the \u201cglands\u201d are coiled tubes of columnar epithelial cells; some the epithelial cells are tall and eosinophilic, whereas others are shorter and more basophilic). In addition to some fibroblasts and a few delicate collagen fibers, you should see quite a few plasma cells<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/view.apml?X=-0.289979608430315&amp;Y=-0.0947460070480663\">[example]<\/a>\u00a0amongst the epithelial\u00a0tubes.<\/p>\n<p><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/view.apml?X=-0.219785216592467&amp;Y=0.00469172775183228&amp;Zoom=12.5\"><strong>Slide 40<\/strong><\/a>\u00a0is also a very good specimen to examine the pseudostratified, ciliated columnar epithelium of the trachea. Note also that the\u00a0<span style=\"text-decoration: underline;\">basement<\/span>\u00a0<span style=\"text-decoration: underline;\">membrane<\/span>\u00a0underlying this particular epithelium is especially prominent.\u00a0<span style=\"text-decoration: underline;\">Type IV<\/span>\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>, which does not form fibrils, but rather a fine meshwork, is present in all basement membranes. The basal lamina is anchored to the underlying connective tissue by fine fibrils of\u00a0<span style=\"text-decoration: underline;\">type VII<\/span>\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>\u00a0(you obviously can\u2019t tell this looking at it in the light microscope, but you should recall this from\u00a0lecture).<\/p>\n<h3><strong>Neutrophils<\/strong><\/h3>\n<ul>\n<li><strong>Slide 29 (small intestine, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/029-1_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<\/ul>\n<p>Look in the lamina propria amongst the plasma cells and you will find neutrophils<span style=\"text-decoration: underline;\">\u00a0<\/span>that have emigrated from the bloodstream into the tissue space as part of the immune response.\u00a0 Neutrophils can be identified by their granular cytoplasm and their multilobular, condensed nuclei.\u00a0 Because of their nuclear morphology, they are frequently also called \u201c<span style=\"text-decoration: underline;\">polymorphonuclear leukocytes<\/span>\u201d (aka \u201cPMNs\u201d or \u201c<span style=\"text-decoration: underline;\">polys<\/span>\u201d).\u00a0 Neutrophils generally enter tissues in large numbers only in response to a disease stimulus.\u00a0\u00a0 However, as seen in this slide, it is quite normal to find them in tissues such as the gut where foreign substances frequently invoke an inflammatory response.\u00a0 You will study neutrophils in much greater detail in other sequences and in your histopathology course, but it is useful for now to at least be able to recognize them in various tissues and\u00a0organs.<\/p>\n<h3><strong>Macrophages<\/strong><\/h3>\n<ul>\n<li><strong>Slide 26 (lymph node, H&amp;E)\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/026_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/026_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<\/ul>\n<p>With low power, locate the\u00a0<strong>medulla<\/strong>\u00a0(the interior) of the lymph node.\u00a0 Look for a region characterized by interlacing cords of cells.\u00a0<span style=\"text-decoration: underline;\">Macrophages<\/span>\u00a0are the biggest, rounded cells that are floating free in the spaces between the cords of cells.\u00a0 Many of the free cells in these medullary sinuses cannot be identified; however, the large rounded cells, with eccentrically placed, vesicular nuclei are the ones you should try to\u00a0find.<\/p>\n<p><em>Many of these macrophages contain phagocytosed red blood cells or the brownish breakdown pigment, hemosiderin (which is the result of lysosomal action on the ingested red blood cells.)<\/em>.\u00a0 Be sure you can identify a macrophage and not just a bunch of cells superimposed upon one another.\u00a0 Macrophages can be seen also in the\u00a0<strong>subcapsular\u00a0<\/strong><strong>sinus<\/strong>\u00a0(the lighter staining area just under the capsule at the periphery of the lymph\u00a0node).<\/p>\n<p>The \u201cmononuclear phagocyte system\u201d (also called the \u201creticuloendothelial system\u201d for historic reasons) consists of free and fixed macrophages throughout the body.\u00a0 These cells are important in removing all kinds of debris from the body as well as playing a major role in the immune\u00a0response.<\/p>\n<h3><strong>Fat\u00a0Cells<\/strong><\/h3>\n<ul>\n<li><strong>Slide 152 (pharynx, H&amp;E)<\/strong><strong>\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Digestive%20System\/Pharynx%20Esophagus%20and%20Stomach\/152_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Digestive%20System\/Pharynx%20Esophagus%20and%20Stomach\/152_HISTO_40X.svs\/is.sis?X=0&amp;Y=0&amp;zoom=1.29654335961189&amp;chost=141.214.65.171\">ImageScope<\/a><\/li>\n<li><strong>Slide 30 (mesentery, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/030_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/030_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<li><strong>Slide H2 (fetal thorax, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/WesternUniv\/H2.svs\/view.apml?X=0&amp;Y=0&amp;zoom=2.1344377190188\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/WesternUniv\/H2.svs\/is.sis?X=0&amp;Y=0&amp;zoom=2.1344377190188&amp;chost=141.214.65.171\">ImageScope<\/a>\u00a0(virtual slide courtesy of Western\u00a0University)<\/li>\n<\/ul>\n<p><strong>Slide 152\u00a0<\/strong>is a section from the pharynx.\u00a0\u00a0 \u00a0Locate the\u00a0<strong>large clear\u00a0<\/strong>circles\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/152_HISTO_20X.svs\/view.apml?X=0.0146807193849723&amp;Y=0.00803494799636945&amp;Zoom=25.0\">[example]<\/a>\u00a0in the connective tissue that sits beneath the epithelium.\u00a0 These are\u00a0<span style=\"text-decoration: underline;\">fat<\/span>\u00a0<span style=\"text-decoration: underline;\">cells<\/span>\u00a0(or\u00a0<span style=\"text-decoration: underline;\">adipocytes<\/span>).\u00a0 In white or unilocular adipose tissue, lipids are stored as a single, non-membrane bound droplet in these cells.\u00a0 A fatty tissue called brown or multilocular fat, produced during fetal development, has adipocytes that contain\u00a0<strong>multiple<\/strong>\u00a0fat droplets. Brown fat is important for thermoregulation in newborns and hibernating mammals. In humans, brown fat is widely distributed throughout the body in the first decade of life, but it then disappears except for regions around the kidney, suprarenal glands, aorta, neck and mediastinum. None of our slides of adult tissue shows any brown fat, however this rather unique tissue can be seen in\u00a0<strong>slide\u00a0<\/strong><strong>H2<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/WesternUniv\/H2.svs\/view.apml?X=-0.243351315111056&amp;Y=0.147051200010625&amp;zoom=50\">[example]<\/a>, which is from a developing\u00a0fetus.<\/p>\n<p>Look for\u00a0<span style=\"text-decoration: underline;\">adipose<\/span>\u00a0<span style=\"text-decoration: underline;\">tissue<\/span>\u00a0in\u00a0<strong>Slide #30<\/strong>\u00a0which is taken from abdominal mesentery (the connective tissue that suspends the viscera within the abdominal cavity). Some of the individual fat cells are often broken during tissue preparation, but the overall impression of what the tissue looks like is the important\u00a0point.<\/p>\n<h3><strong>Mast\u00a0Cells<\/strong><\/h3>\n<ul>\n<li><strong>Slide 160<\/strong>\u00a0<strong>(stomach, PAS\u00a0&amp;\u00a0Azure II)<\/strong><strong>\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/160_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/160_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<\/ul>\n<p>Mast cells can only be definitively recognized with special stains such as\u00a0<strong>Azure II<\/strong>\u00a0and\u00a0<strong>toluoidine blue<\/strong>\u00a0that identify the heparin storage granules (Azure metachromatically stains the heparin purple). Mast cells are most abundant in the connective tissue associated with the lining of the digestive and respiratory systems, and your collection just so happens to contain a tissue section from the stomach that has been stained with PAS and Azure II. As you look at this section, you will see a very obvious layer of mucous epithelial cells (PAS also reacts with the carbohydrate-rich mucin). However, to see the mast cells, you will need to look deeper in the<strong>\u00a0submucosa<\/strong>where you should find small, ovoid cells amongst the collagen fibers with spherical, eccentric nuclei and\u00a0<strong>intensely basophilic<\/strong>\u00a0(dark purple to black)<strong>\u00a0granules<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/160_HISTO_40X.svs\/view.apml?X=-0.237010226729416&amp;Y=0.179379468459487&amp;zoom=100\">[example]<\/a>. The granules are often so dark that they obscure the\u00a0nucleus.<\/p>\n<h2>Reticular\u00a0tissue<\/h2>\n<ul>\n<li><strong>Slide 27 (lymph node, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/027_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/027_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<li><strong>Slide 28 (lymph node, silver stain)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/028-2_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/028-2_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<\/ul>\n<p>The fine collagenous network that provides support in the bone marrow, lymphatic organs, around individual smooth muscle cells, and beneath most epithelia is composed mainly of Type III collagen. The collagen has an associated carbohydrate moiety (uncharacterized) that can reduce Ag+ to metallic Ag revealing a network (reticulum) of fine, black fibrils. These are termed reticular (or rarely, argyrophilic= \u201csilver loving\u201d) fibers. On\u00a0<strong>slide #27<\/strong>\u00a0look at the accumulations of<strong>darkly stained cells<\/strong>\u00a0(lymphocytes in a lymph node). Note at high power that fibrils or fibers of any type cannot be readily observed. Now with\u00a0<strong>slide #28<\/strong>\u00a0(make sure your slide is stained with silver; it should say \u201cAg\u201d on the label!), note how a network of\u00a0<strong>fine black fibrils<\/strong>\u00a0is present in this same tissue following silver staining. These are reticular fibers, found in skin, muscle and blood vessels. The reticular fibers provide physical support for all the cells present in tissues subject to stretching. You are not responsible for recognizing reticular fibers unless a silver stain is\u00a0used.<\/p>\n<p>Please remember that virtually all cells (except for those in the brain and spinal cord) are provided with some degree of support by collagen (reticular fibers) even though that may not be apparent with H&amp;E staining. (Masson Trichrome and silver staining are frequently used in pathology to determine if connective tissue has proliferated\u2013a sign of damage and attempted repair\u2013in the liver, kidney and\u00a0lung.)<\/p>\n<h2><strong>DENSE CONNECTIVE\u00a0TISSUE<\/strong><\/h2>\n<h3><strong>DENSE IRREGULAR CONNECTIVE\u00a0TISSUE<\/strong><\/h3>\n<ul>\n<li><strong>Slide 33 (skin, Verhoeff stain)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/033_HISTO_20X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/033_HISTO_20X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<li><strong>Slide 250-1<\/strong>\u00a0<strong>(vagina, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/250-1_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/250-1_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<li><strong>Slide 250-2<\/strong>\u00a0<strong>(vagina, trichrome)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Female%20Reproductive%20System\/250-2_HISTO_40X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Female%20Reproductive%20System\/250-2_HISTO_40Xsvs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<\/ul>\n<p>The area beneath the stratified squamous epithelium shown in\u00a0<strong>slide 33<\/strong>\u00a0is the\u00a0<span style=\"text-decoration: underline;\">dermis<\/span>, which is composed of dense irregular connective tissue.\u00a0 In this section, the fibers clearly predominate.\u00a0 This slide has been stained with iron hematoxylin and eosin so you can see\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>\u00a0<span style=\"text-decoration: underline;\">fibers<\/span>(orange) as well as elastic fibers (purple\/black) in the dermis\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/033_HISTO_20X.svs\/view.apml?X=0.0461274926182096&amp;Y=-0.275428605243772&amp;zoom=50&amp;navwindow=0\">[example]<\/a>.\u00a0Note how the diameter of the fibers varies with location.\u00a0 In the region immediately beneath the epidermis you can see how the elastic fibers are interconnected forming an elaborate,\u00a0<strong>delicate<\/strong>\u00a0net of fibers\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/033_HISTO_20X.svs\/view.apml?X=-0.115515340016333&amp;Y=-0.38113644185685&amp;zoom=100&amp;navwindow=0\">[example]<\/a>amongst thin strands of collagen. However, deeper in the dermis, the collagen and elastic fibers are much\u00a0thicker.<\/p>\n<p><strong>Slide 250<\/strong>\u00a0which you used to look at stratified squamous non-keratinizing epithelium is also useful for the study of connective tissue (we will also use this slide to study smooth muscle and peripheral ganglia).\u00a0 Be sure you look at both the\u00a0<strong>H&amp;E<\/strong>\u00a0and\u00a0<strong>Masson trichrome-stained<\/strong>\u00a0slides as they provide an excellent opportunity to see how\u00a0<span style=\"text-decoration: underline;\">collagen<\/span>\u00a0stains in connective tissue when either stain is applied.\u00a0 When we study smooth muscle and peripheral nerve tissue we will come back to this slide to try and distinguish between collagen fibers and fascicles of smooth muscle and\/or nerve fibers and\u00a0ganglia.<\/p>\n<p><strong>NOTE:<\/strong>\u00a0\u00a0<strong>Slide 250<\/strong>\u00a0illustrates a point about the limits of classification schemes. Even though we try to set up rigid categories (e.g. \u201cloose\u201d versus \u201cdense\u201d connective tissue), sometimes it is not always possible to classify connective tissue in a given section; it may be a little loose, a little dense, a little fatty, etc. In these particular instances, don\u2019t worry so much about trying to\u00a0<strong>exactly classify<\/strong>\u00a0the tissue per se, but at least try to identify the cellular and extracelluar components that you can (also bear in mind that you can\u2019t always definitely identify<strong>\u00a0every\u00a0<\/strong>cell) and think how its overall appearance reflects its\u00a0<strong>function<\/strong>.<\/p>\n<h3><strong>DENSE REGULAR CONNECTIVE\u00a0TISSUE<\/strong><\/h3>\n<h4><strong>Collagenous<\/strong><\/h4>\n<ul>\n<li><strong>Slide 106<\/strong>\u00a0<strong>(plantar skin and tendon, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/106_HISTO_40X.svs\/view.apml?\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/106_HISTO_40X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<li><strong>Slide 112 (plantar skin and tendon, H&amp;E)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Integumentary%20System\/112_HISTO_40X.svs\/view.apml?X=0&amp;Y=0&amp;zoom=1.6670216542421\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Integumentary%20System\/112_HISTO_40X.svs\/is.sis?X=0&amp;Y=0&amp;zoom=1.6670216542421&amp;chost=141.214.65.171\">ImageScope<\/a><\/li>\n<\/ul>\n<p><strong>Slide 106<\/strong>\u00a0and\u00a0<strong>112\u00a0<\/strong>have bits of well preserved flexor tendon at the top of the section (the tissue at the\u00a0<strong>very top<\/strong>\u00a0of slide 112 is actually skeletal muscle -which you\u2019ll study in the next lab; the tendon is just below it).\u00a0 Note the\u00a0<strong>regular orientation<\/strong>\u00a0of the collagen fibers (there\u2019s a bit a \u201cwaviness\u201d but you should get the idea). You should also observe that there aren\u2019t a lot of cells, a characteristic of \u201cdense\u201d connective tissue. The very small cracks between the fibers are just artifacts of shrinkage that occured during tissue preparation. Of course, there are some places where there are breaks in the dense regular connective tissue of the tendon containing loose connective tissue associated with nerves and blood vessels or the occasional bit of adipose\u00a0tissue.<\/p>\n<h4><strong>Elastic\u00a0tissue<\/strong><\/h4>\n<ul>\n<li><strong>slide 36 (Aorta, aldehyde fuchsin)<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/036_HISTO_20X.svs\/view.apml\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/036_HISTO_20X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<li><strong>slide 88 (Aorta, H&amp;E)\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/088_HISTO_20X.svs\/view.apml?width=953&amp;height=1025\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/088_HISTO_20X.svs\/is.sis?chost=141.214.65.171\">ImageScope<\/a><\/li>\n<\/ul>\n<p>These slides are examples of regularly arranged sheets (<span style=\"text-decoration: underline;\">lamellae<\/span>) of\u00a0<span style=\"text-decoration: underline;\">elastin<\/span>.\u00a0\u00a0<strong>Slide 36<\/strong>\u00a0is stained with aldehyde fuchsin and Masson trichrome (Aldehyde Fuchsin, Fe. Hem.\u00a0&amp;\u00a0Mass.), so the elastic lamellae are\u00a0<strong>purple<\/strong>.\u00a0<strong>Slide 88<\/strong>\u00a0is stained with H&amp;E where the concentric rings of elastic lamellae are intensely stained with eosin giving a\u00a0<strong>glassy red\u00a0<\/strong><strong>appearance<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Cardiovascular%20System\/088_HISTO_20X.svs\/view.apml?X=0.0849156577983365&amp;Y=0.131259364204137&amp;zoom=50\">[example]<\/a>\u00a0(one of the few places where elastin is easy to recognize in H&amp;E\u00a0sections).<\/p>\n<p>Two other locations where elastic fibers can be readily seen in H&amp;E sections are in the lamina propria of the pharynx (<strong>slide 152<\/strong>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Digestive%20System\/Pharynx%20Esophagus%20and%20Stomach\/152_HISTO_40X.svs\/view.apml?X=0.276980887872605&amp;Y=0.240060695222288&amp;zoom=25\">WebScope<\/a>\u00a0<a href=\"http:\/\/141.214.65.171\/Histology\/Digestive%20System\/Pharynx%20Esophagus%20and%20Stomach\/152_HISTO_40X.svs\/is.sis?X=0.276980887872605&amp;Y=0.240060695222288&amp;zoom=25&amp;chost=141.214.65.171\">ImageScope<\/a>) and the trachea (<strong>slide 40\u00a0<\/strong><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/view.apml?\">WebScope<\/a><a href=\"http:\/\/141.214.65.171\/Histology\/Basic%20Tissues\/Epithelium%20and%20CT\/040_HISTO_40X.svs\/is.sis?X=-0.280059541325328&amp;Y=0.0776299677933251&amp;Zoom=37.5&amp;chost=141.214.65.171\">ImageScope<\/a>).\u00a0<em>Unlike the tissue of the aorta which would be classified as \u201cregular,\u201d these tissues are obviously\u00a0<strong>irregular<\/strong>\u00a0but they\u2019re mentioned here for the purpose of illustrating how aggregates of elastic fibers appear in H&amp;E-stained sections.<\/em>\u00a0Just as in the H&amp;E-stained aorta, the elastic fibers in the pharynx and trachea are glassy and orange-red \u2013they appear as stippled dots because they\u2019ve been cut in cross\u00a0section.<\/p>\n<div>\n<div>\n<h2>Electron\u00a0Micrographs<\/h2>\n<\/div>\n<div>\n<div>\n<div>\n<ul>\n<li><strong>26 Connective Tissue &#8211; Dense Irregular\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/026%20-%20Connective%20tissue_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/026%20-%20Connective%20tissue_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>Dense Connective Tissue. Note the alternating layers of fibroblasts and collagenous fiber bundles. Make sure you can see the difference between cross sectioned and longitudinally sectioned collagenous fibrils. In dense connective tissue, which type of cell is most common? (CT7)<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<ul>\n<li><strong>18 Loose Connective Tissue &#8211; Lamina propria of tracheal mucosa\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/018%20-%20Connective%20tissue_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/018%20-%20Connective%20tissue_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>Loose Connective Tissue. In this micrograph of loose connective tissue of the tracheal mucosa numerous (labeled) cells of the connective tissue are present. Note the relative size of the different cell types, their shapes, amount of rough ER and variously sized granules and inclusions. Then use your text and atlas to review the diagnostic features of each connective tissue cell present in the micrograph. Note the paucity of collagen fibrils. What was present in the &#8220;empty&#8221; looking intercellular space? (CT10)<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<ul>\n<li><strong>27 Elastic Connective Tissue &#8211; Junction of Media and Adventilia of artery\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/027%20-%20Elastic%20tissue_001.svs\/view.apml\">Webscope<\/a> <a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/027%20-%20Elastic%20tissue_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>Observe the branching nature of the elastic fiber and the &#8220;mantle&#8221; of elastic microfibrils. The cross banding of the collagenous fibrils is easily observed.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<ul>\n<li><strong>28 Collagen and Elastin &#8211; Cross section of Chorda Tendinea\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/028%20-%20Collagen%20&amp;%20elastin_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/028%20-%20Collagen%20&amp;%20elastin_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>Observe the mixture of collagen and elastic fibers in this cross section of chorda tendinea. Although collagen fibers mostly fill the view, there are numerous elastic fibers, which provide the elasticity essential for the function of the tissue.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<ul>\n<li><strong>29 Tendon &#8211; Longitudinal section\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/029%20-%20Tendon_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/029%20-%20Tendon_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>Note the uniform distribution of regularly arranged collagen fibers (type I).<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<ul>\n<li><strong>25 Connective Tissue &#8211; Fibroblast\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/025%20-%20Fibroblast_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/025%20-%20Fibroblast_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>Observe the large amount of rough endoplasmic reticulum (ER) in these cells. Is this an indication of an active or inactive cell? (CT9) Test your ability to identify different organelles at this magnification!<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<ul>\n<li><strong>20 Mast cell &#8211; Human\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/020%20-%20Mast%20cell_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/020%20-%20Mast%20cell_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>Mast cells contain a mixture of granule types reflective of the variety of substances they secrete. Histamine and heparin are found in the more &#8220;regular&#8221; looking granules (evenly dark and round). Other secretory products include leukotrienes and other phospholipid derivatives, which are made from the sheets of membranes arranged as lamella, whorls, or even scroll-like bodies within the more irregular appearing granules. What are the secretory products of the mast cell? (CT11)<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<ul>\n<li><strong>63 Macrophage\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/063%20-%20Macrophage_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/063%20-%20Macrophage_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>Tissue macrophages can be found in many different organs. As they have a phagocytic function, removing pathogens and cell debris, macrophages usually contain abundant primary and secondary lysosomes.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<ul>\n<li><strong>21 Plasma cell\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/021%20-%20Plasma%20cell_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/021%20-%20Plasma%20cell_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>This electron micrograph shows a typical secretory cell, a plasma cell, which secretes immunoglobulin protein. Many of the major types of cellular organelles are visible in this image. In the nucleus, areas of euchromatin and heterochromatin can easily be identified. Use these micrographs to review the structure of organelles. Be sure you recognise favourable sections of the nucleas, mitochondria, and rough ER.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<ul>\n<li><strong>23 Fat Cells &#8211; Mature\u00a0<i><\/i><\/strong><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/023%20-%20Fat%20cells_001.svs\/view.apml\">Webscope<\/a><a href=\"http:\/\/virtualslides.med.umich.edu\/Histology\/EMsmallCharts\/3%20Image%20Scope%20finals\/023%20-%20Fat%20cells_001.svs\/is.sis?chost=virtualslides.med.umich.edu\">\u00a0Imagescope<\/a><\/li>\n<\/ul>\n<\/div>\n<div>\n<div>\n<p>This electron micrograph depicts mature fat cells. You can see one large lipid droplet in the cytoplasm of each cell. The nuclei of many cells are not included in the field of view. Brown fat cells would have several small lipid droplets all of which would be roughly the same size. Remember that each fat cell is enclosed by a thin basal lamina (Unfortunately, in these examples you can\u2019t see the basal lamina). Where are the nuclei of the fat cells? (CT8)<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<h3>Review Questions<\/h3>\n<div style=\"line-height: 1.5em;\">\n<div>1. What type of epithelium lines the luminal surface of the\u00a0intestine?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0The luminal surface of the intestine is made up of a simple columnar\u00a0epithelium.<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>2. Why is rough endoplasmic reticulum\u00a0basophilic?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0The ribosomes attached to rough ER are associated with both ribosomal and messenger RNA &#8211; these nucleic acids carry a net negative charge and bind basic dyes (which are positively\u00a0charged).<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>3. What type of lining epithelium is present in the\u00a0pharynx?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Stratified squamous non-keratinizing epithelium lines the\u00a0pharynx.<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>4. Can you see a nucleus in each fat\u00a0cell?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0No, because not all nuclei are on the plane of\u00a0section.<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>5. What do mast cells\u00a0do?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Mast cells are actively involved in a host\u2019s immune response and produce many substances, some of which are heparin and histamine. The degranulation of these cells is responsible for triggering type I, immediate hypersensitivity reactions. Type I reactions, also called anaphylactic reactions, are something you will learn about while studying the immune system later on, but for now, here is a quick explanation. IgE is an antibody, produced by plasma cells, that has a high affinity for mast cells and basophils. The antibody binds mast cells and waits for a second exposure to whatever it happens to be responsive to (an allergen). When the IgE binds an appropriate molecule, it will trigger degranulation of the mast cell and the vasodilation, congestion, bronchiolar constriction, wheezing, etc. associated with allergies and other type I\u00a0reactions<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>6. Why do cells actively secreting proteins exhibit basophilic\u00a0cytoplasm?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Protein secreting cells have a basophilic cytoplasm because they are full of rough ER, which stains with hematoxylin, a basic\u00a0dye.<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>7. In dense connective tissue, which type of cell is most\u00a0common?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Dense connective tissue is full of\u00a0fibroblasts.<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>8. Where are the nuclei of fat\u00a0cells?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Fat cell nuclei are on the periphery of the cell and may or may not be in the plane of\u00a0section.<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>9. Is rough ER an indication of an active or an inactive\u00a0cell?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Large amounts of rough ER indicate that the cell is active and is producing large amounts of\u00a0proteins.<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>10. What was present in the \u201cempty\u201d looking intercellular\u00a0space?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0The empty space within connective tissue is ground\u00a0substance.<\/p>\n<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<div>11. What are the secretory products of the mast\u00a0cell?<\/div>\n<\/div>\n<div style=\"line-height: 1.5em;\">\n<p style=\"padding-left: 30px;\"><a href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue#\">Answer<\/a>:\u00a0Heparin and histamine are just some of the contents of mast cell\u00a0granules.<\/p>\n<\/div>\n<\/div>\n<p><iframe src=\"https:\/\/lumenoea.herokuapp.com\/assessments\/load?src_url=https:\/\/lumenoea.herokuapp.com\/api\/assessments\/401.xml&#38;results_end_point=https:\/\/lumenoea.herokuapp.com\/api&#38;assessment_id=401&#38;confidence_levels=true&#38;enable_start=true&#38;eid=https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/chapter\/histology-slides\/\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:400px;\"><\/iframe><\/p>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-1771\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Connective Tissue . <strong>Provided by<\/strong>: Histology and Virtual Microscopy Learning Resources. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue\">http:\/\/histology.med.umich.edu\/medical\/connective-tissue<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/4.0\/\">CC BY-NC-SA: Attribution-NonCommercial-ShareAlike<\/a><\/em><\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":74,"menu_order":14,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Connective Tissue \",\"author\":\"\",\"organization\":\"Histology and Virtual Microscopy Learning Resources\",\"url\":\"http:\/\/histology.med.umich.edu\/medical\/connective-tissue\",\"project\":\"\",\"license\":\"cc-by-nc-sa\",\"license_terms\":\"\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1771","chapter","type-chapter","status-publish","hentry"],"part":1737,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/pressbooks\/v2\/chapters\/1771","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/wp\/v2\/users\/74"}],"version-history":[{"count":15,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/pressbooks\/v2\/chapters\/1771\/revisions"}],"predecessor-version":[{"id":2805,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/pressbooks\/v2\/chapters\/1771\/revisions\/2805"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/pressbooks\/v2\/parts\/1737"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/pressbooks\/v2\/chapters\/1771\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/wp\/v2\/media?parent=1771"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/pressbooks\/v2\/chapter-type?post=1771"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/wp\/v2\/contributor?post=1771"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-ap1\/wp-json\/wp\/v2\/license?post=1771"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}