{"id":4493,"date":"2017-03-29T17:12:46","date_gmt":"2017-03-29T17:12:46","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/wm-biology2\/?post_type=chapter&#038;p=4493"},"modified":"2024-04-26T01:44:13","modified_gmt":"2024-04-26T01:44:13","slug":"organogenesis","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-biology2\/chapter\/organogenesis\/","title":{"raw":"Organogenesis","rendered":"Organogenesis"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Describe the process of organogenesis<\/li>\r\n<\/ul>\r\n<\/div>\r\nOrgans form from the germ layers through the process of differentiation. During differentiation, the embryonic stem cells express specific sets of genes which will determine their ultimate cell type. For example, some cells in the ectoderm will express the genes specific to skin cells. As a result, these cells will differentiate into epidermal cells. The process of differentiation is regulated by cellular signaling cascades.\r\n\r\nScientists study organogenesis extensively in the lab in fruit flies (<em>Drosophila<\/em>) and the nematode <em>Caenorhabditis elegans<\/em>. <em>Drosophila<\/em>\u00a0have segments along their bodies, and the patterning associated with the segment formation has allowed scientists to study which genes play important roles in organogenesis along the length of the embryo at different time points. The nematode <em>C.elegans<\/em> has roughly 1000 somatic cells and scientists have studied the fate of each of these cells during their development in the nematode life cycle. There is little variation in patterns of cell lineage between individuals, unlike in mammals where cell development from the embryo is dependent on cellular cues.\r\n\r\nIn vertebrates, one of the primary steps during organogenesis is the formation of the neural system. The ectoderm forms epithelial cells and tissues, and neuronal tissues. During the formation of the neural system, special signaling molecules called growth factors signal some cells at the edge of the ectoderm to become epidermis cells. The remaining cells in the center form the neural plate. If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue.\r\n\r\nThe neural plate undergoes a series of cell movements where it rolls up and forms a tube called the <b>neural tube<\/b>, as illustrated in\u00a0Figure 1. In further development, the neural tube will give rise to the brain and the spinal cord.\r\n\r\n[caption id=\"attachment_3075\" align=\"aligncenter\" width=\"500\"]<img class=\"wp-image-3075\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/09214317\/Figure_43_06_01.jpg\" alt=\"Illustration shows a flat sheet. The middle of the sheet is the neural plate, and the epidermis is at either end. The neural plate border separates the neural tube from the epidermis. During convergence the plate folds, bringing the neural folds together. The neural folds fuse, joining the neural plate into a neural tube. The epidermis separates and folds around the outside.\" width=\"500\" height=\"746\" \/> Figure 1.\u00a0The central region of the ectoderm forms the neural tube, which gives rise to the brain and the spinal cord.[\/caption]\r\n\r\nThe mesoderm that lies on either side of the vertebrate neural tube will develop into the various connective tissues of the animal body. A spatial pattern of gene expression reorganizes the mesoderm into groups of cells called <b>somites<\/b> with spaces between them. The somites, illustrated in Figure 2 will further develop into the ribs, lungs, and segmental (spine) muscle. The mesoderm also forms a structure called the notochord, which is rod-shaped and forms the central axis of the animal body.\r\n\r\n[caption id=\"attachment_3076\" align=\"aligncenter\" width=\"500\"]<img class=\"wp-image-3076\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/09214405\/Figure_43_06_02.jpg\" alt=\" Embryo resembles a segmented earthworm with a bulging head.\" width=\"500\" height=\"533\" \/> Figure 2.\u00a0In this five-week old human embryo, somites are segments along the length of the body. (credit: modification of work by Ed Uthman)[\/caption]\r\n\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/7050d4cb-8676-45dc-9f4b-6e7289d7ffd8\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Describe the process of organogenesis<\/li>\n<\/ul>\n<\/div>\n<p>Organs form from the germ layers through the process of differentiation. During differentiation, the embryonic stem cells express specific sets of genes which will determine their ultimate cell type. For example, some cells in the ectoderm will express the genes specific to skin cells. As a result, these cells will differentiate into epidermal cells. The process of differentiation is regulated by cellular signaling cascades.<\/p>\n<p>Scientists study organogenesis extensively in the lab in fruit flies (<em>Drosophila<\/em>) and the nematode <em>Caenorhabditis elegans<\/em>. <em>Drosophila<\/em>\u00a0have segments along their bodies, and the patterning associated with the segment formation has allowed scientists to study which genes play important roles in organogenesis along the length of the embryo at different time points. The nematode <em>C.elegans<\/em> has roughly 1000 somatic cells and scientists have studied the fate of each of these cells during their development in the nematode life cycle. There is little variation in patterns of cell lineage between individuals, unlike in mammals where cell development from the embryo is dependent on cellular cues.<\/p>\n<p>In vertebrates, one of the primary steps during organogenesis is the formation of the neural system. The ectoderm forms epithelial cells and tissues, and neuronal tissues. During the formation of the neural system, special signaling molecules called growth factors signal some cells at the edge of the ectoderm to become epidermis cells. The remaining cells in the center form the neural plate. If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue.<\/p>\n<p>The neural plate undergoes a series of cell movements where it rolls up and forms a tube called the <b>neural tube<\/b>, as illustrated in\u00a0Figure 1. In further development, the neural tube will give rise to the brain and the spinal cord.<\/p>\n<div id=\"attachment_3075\" style=\"width: 510px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-3075\" class=\"wp-image-3075\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/09214317\/Figure_43_06_01.jpg\" alt=\"Illustration shows a flat sheet. The middle of the sheet is the neural plate, and the epidermis is at either end. The neural plate border separates the neural tube from the epidermis. During convergence the plate folds, bringing the neural folds together. The neural folds fuse, joining the neural plate into a neural tube. The epidermis separates and folds around the outside.\" width=\"500\" height=\"746\" \/><\/p>\n<p id=\"caption-attachment-3075\" class=\"wp-caption-text\">Figure 1.\u00a0The central region of the ectoderm forms the neural tube, which gives rise to the brain and the spinal cord.<\/p>\n<\/div>\n<p>The mesoderm that lies on either side of the vertebrate neural tube will develop into the various connective tissues of the animal body. A spatial pattern of gene expression reorganizes the mesoderm into groups of cells called <b>somites<\/b> with spaces between them. The somites, illustrated in Figure 2 will further develop into the ribs, lungs, and segmental (spine) muscle. The mesoderm also forms a structure called the notochord, which is rod-shaped and forms the central axis of the animal body.<\/p>\n<div id=\"attachment_3076\" style=\"width: 510px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-3076\" class=\"wp-image-3076\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/09214405\/Figure_43_06_02.jpg\" alt=\"Embryo resembles a segmented earthworm with a bulging head.\" width=\"500\" height=\"533\" \/><\/p>\n<p id=\"caption-attachment-3076\" class=\"wp-caption-text\">Figure 2.\u00a0In this five-week old human embryo, somites are segments along the length of the body. (credit: modification of work by Ed Uthman)<\/p>\n<\/div>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_7050d4cb-8676-45dc-9f4b-6e7289d7ffd8\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/7050d4cb-8676-45dc-9f4b-6e7289d7ffd8?iframe_resize_id=assessment_practice_id_7050d4cb-8676-45dc-9f4b-6e7289d7ffd8\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:300px;\"><br \/>\n\t<\/iframe>\n<\/div>\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-4493\">\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>Biology 2e. <strong>Provided by<\/strong>: OpenStax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\">http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Access for free at https:\/\/openstax.org\/books\/biology-2e\/pages\/1-introduction<\/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":17,"menu_order":20,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Biology 2e\",\"author\":\"\",\"organization\":\"OpenStax\",\"url\":\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Access for free at https:\/\/openstax.org\/books\/biology-2e\/pages\/1-introduction\"}]","CANDELA_OUTCOMES_GUID":"2851a042-52b2-4881-ac7b-7a4c1ea7c15a, 1a232021-2874-4ee3-8cbe-b501e8a64636","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-4493","chapter","type-chapter","status-publish","hentry"],"part":3801,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4493","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":7,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4493\/revisions"}],"predecessor-version":[{"id":8566,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4493\/revisions\/8566"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/parts\/3801"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4493\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/media?parent=4493"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapter-type?post=4493"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/contributor?post=4493"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/license?post=4493"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}