Making Simple But Accurate Line Drawings of Magnified Specimens

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You do not have to be a great artist to make a diagram of the cells and structures you see under a microscope. You only have to be careful to draw something that is approximately the same size and shape as what you see. Follow the following guidelines:

  1. Only draw what you actually see. Even if you expect to see something, if it is not there you should not draw it. Do not base your drawings on what the textbook or some other source tells you should be there. Do not draw things in the shapes that texts or other sources tell you to expect unless you actually see those shapes.
  1. Keep things as simple as possible. Draw strong unbroken lines. Avoid shading or cross-hatching unless there is a very good reason to add them.
  1. Feel free to simply reality by leaving out unnecessary details. Draw what is of interest, but leave out background material, debris, or any other distracting items. Just be careful that, if you are leaving something out, that it isn’t something that is an important part of what you are drawing.

You should always have a basic understanding of what you are looking for before looking in the microscope. Tissues and other microscopic specimens can be confusing and cluttered. If you know in general what you are looking for, and, sometimes more importantly, what you are not looking for, it will make it much easier to find what you want to draw and it will make it much easier to decide how to draw it.

Just remember, what you see under the microscope may look quite different from the perfect specimens that are usually found in the figures put into textbooks and websites. Use the idealized images to track down what you are looking for, but draw he specimen as it actually is, regardless of your expectations.

For instance, in most textbooks, neurons, the most common cell found in nervous tissue, are drawn to look like variations of the drawing in Figure 4.2A.

neurons_diagram-vs-actual

Figure 4-2. A. A typical diagram of a neuron. B. An actual neuron.

 

In the typical diagram of a neuron that appears in texts and on websites, there usually is a clear nucleus, and often a nucleolus visible, too. Sometimes organelles such as mitochondria are visible (there are none in Figure 4-2A.) The dendrites are typically short and branched. There almost always is a single, easily-identifiable axon that is longer than all the dendrites and that branches as it ends.

Figure 4-2B shows an actual neuron as viewed through a microscope. If you view enough neurons through enough different types of microscopes, you can eventually create a composite diagram that incorporates features from many specimens to present a “typical” neuron, but it is unlikely that if you view a single neuron you will see everything in in Figure 4-2A. In fact, often actual specimens look very little like their textbook counterparts. Draw what you see, not what you think you are supposed to see. Just make sure you are looking at what you are supposed to be finding (for instance, a neuron and not a piece of dirt or cell debris), and then draw it as it is, regardless of whether or not it

In the case of the actual neuron in Figure 4-2B, there is no nucleus visible, there is maybe one large projection and one small projection you could call dendrites – but there aren’t many projections – and neither of the projections are branched. There is one long thin projection that is probably an axon, and it is not branched.

If you draw what you see, you end up with a drawing like the one in Figure 4-3B. It does not look like a textbook neuron, but it is a reasonable representation of what is there in this case.

neurons_actual-then-diagrammed

Figure 4-3. A. An actual neuron. B. A drawing of Figure 4.3 A’s neuron.

Most students feel they “cannot draw” and are reluctant to sketch what they are seeing under a microscope. You don’t let your lack of artistic skills stop you.

  1. Draw an outline that approximates the item you want to draw. Don’t obsess about making it match perfectly. Approximate is ok.
  1. Try to get the proportions approximately right. If something is half as big, or as third as big, as something else, make it that way in the drawing, too.
  1. Do not draw everything you see. Improve on reality by only drawing the parts of the specimen you are interested in. You do not have to draw every bit of debris or dirt. Decide what the important parts of your specimen are and draw only those.
  1. Do not use shading or cross-hatching unless there is a very good reason to do so. It will actually make it easier to understand your drawing if you stick to drawing just outlines. It will also be easier and quicker to draw.

 

Lab 4 Exercises 4.5

  1. Get a human blood smear slide. Rotate your lowest power objective into place on your microscope.
  1. Follow the checklist in Lab Exercise 4.3 until you are viewing the blood smear under you 40x objective.
  1. You will see mostly red blood cells. They will probably be pinkish and they will be the circles without nuclei. Occasionally, some will appear to have blank circles in their centers, but these are not nuclei. If you search around your slide using your stage controls, you will find the rare circular cells with nuclei. These are white blood cells. There will be less than one white blood cell for every 100 red blood cells. These white blood cells will probably be light blue or grey and have purple or dark blue nuclei. Their nuclei will not always be round.
  1. Find a section of your slide with two or more white blood cells among all the red blood cells.
  1. In the circle below, draw four or five representative red blood cells (do not draw all the red blood cells you see) and draw all the white blood cells in your field of view. Pay careful attention to drawing the white blood cell nuclei as accurately as possible.
  1. Do not remove or change the position of your slide until the instructor has verified that your white blood cells are drawn accurately.
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