Society has moved into the age of virtual reality. This computer-generated trend has wide-sweeping implications in the classroom. Specific to anatomy, impressive 3D modeling programs permit students to dissect simulated bodies pixel by pixel. It is exciting and often more cost-effective. Virtual dissection, without doubt, can play a significant role in the current learning environment. However, as stated by Rene Descartes, “And so that they might have less difficulty understanding what I shall say about it, I should like those who are unversed in anatomy to take the trouble, before reading this, of having the heart of a large animal with lungs dissected before their eyes (for it is in all respects sufficiently like that of a man)”. This idea leads me to my argument; there is no replacement for the real thing.
We as teachers must incorporate a variety of learning tools for a student to truly understand and appreciate anatomical structure. Anatomical structure also needs to be related to physiological function. Is there anyone reading this that has not repeated the mantra “form determines function” hundreds or thousands of times during their teaching? The logistical and financial restrictions to human cadavers, necessitates the frequent incorporation of chemically preserved specimens into our laboratory curriculum. Course facilitators often employ a cat or a pig as a substitute for the human body. I am not advocating against the use of preserved specimens or virtual programs for that matter (and kudos to my fellow facilitators who have learned the arduous techniques required to dissect a preserved specimen). However, it is my opinion that it is a time consuming assignment with limited educational end points. Not to mention the rising specimen costs and limited vendor options. The cost of a preserved cat is now ~$40, while the average cost of a live mouse is only ~$5. Two very important components necessary to understand the concept that form determines function are missing from preserved specimens (even cadavers). These two components are: texture and color. With respect to color, the tissues of preserved specimens are subtle variations of gray, completely void of the Technicolor show of the living organism. Further, texture differences are extremely difficult to differentiate in a preserved specimen. Compare this to a fresh or live specimen and the learning tools are innumerable. You might argue that mice are much smaller, but dissecting microscopes can easily enhance the dissection and in my experience far outweigh the noxious experience of dissecting a chemically preserved organism.
To further convince you of the value of dissecting fresh tissue I would like to present a couple of examples. First, why is the color of tissue important? One of the most important bodily pigments is hemoglobin. Hemoglobin, as we all know, is the pigment that gives blood its red color. Therefore the color of a tissue often reflects the level of the tissue vascularity and often (but of course not always) in turn the ability of that tissue to repair or regenerate. Simply compare the color of the patellar tendon (white) to the red color of the quadriceps. Muscles being highly vascularized have a much greater ability to regenerate than non-vascular connective tissue such as the patellar tendon. In addition, muscles contain myoglobin, a red protein very similar to hemoglobin. Two clear examples of teaching opportunities that would be missed with the traditional use of preserved specimens.
Texture is completely lost with chemical preservation as tissues become hardened and rubbery. My students are always blown away by the fact you can completely eliminate the overall structure of the brain by pressing it between their two fingers. The tactile experience of holding the delicate brain allows students to explore how form begets function begets pathology. Traumatic brain injury (TBI) has become a hot topic in our culture. We no longer see children riding bicycles without helmets, the National Football League has new rules regarding tackle technique and my 8-year-old soccer player is penalized for headers during game play. What better way to educate a new generation of students just how delicate nervous tissue is than by having them “squash” a mouse brain? Regardless, of the amazing skull that surrounds the brain and the important fluid in which it floats, a hit to the head can still result in localized damage and this tactile experience emphasizes this in a way no virtual dissection could ever accomplish.
Finally, I would like to discuss a topic close to my heart that does require a non-preserved large animal specimen. The function of arteries and veins is vastly different based on the structure of elastic or capacitance vessels, respectively. For example, the deer heart allows easy access to the superior or inferior vena cava (veins that are thin and easily collapsed) and the aorta (thick and elastic artery) permitting valuable teaching moments on vessel structural variability for divergent physiological function. These structures on a preserved specimen are usually removed just as they enter the heart making them very difficult to evaluate.
These are just some elementary examples. Numerous concepts can be enhanced with the added illustrations of texture and color. When presented with both options, my students always choose the fresh tissue! The wonder and excitement of handling fresh tissue has become a hallmark of our Anatomy and Physiology course and is regularly mentioned as student’s favorite example of hands-on learning in the classroom.
I have to end this with a special shout-out to my dear lab adjunct Professor Elizabeth Bain MSN, RN. Liz has made access to deer heart and lungs an easy task for me.