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Dissection Techniques & Alternatives

Instructor: Stephanie Gorski

Steph has a PhD in Entomology and teaches college biology and ecology.

In this lesson, we'll talk about the importance of dissection, and hopefully about how to enjoy it! We'll introduce some safety rules and tools, and alternatives to dissection as well.

Why Dissect?

How important is dissection? In the sixteenth century, professors in European medical schools simply read a book by the ancient Greek physician Galen aloud while a surgeon showed students the relevant parts from the corpse of an executed criminal. The professors would never look at the cadavers, and the students barely would, because it was believed that everything worth knowing was in Galen's book.

Andreas Vesalius (1514-1564), a young medical professor, began dissecting corpses himself only to find that Galen was often very wrong. In Galen's culture, dissecting a human was taboo, and Vesalius finally determined that Galen had never dissected one! Vesalius made it his life's work to dissect human cadavers, and show medical students how the human body was actually structured rather than relying on ancient Greek texts.

Now, in part because of Vesalius, you live in a world of science-based and observation-based medicine. If you get sick, you will be treated with the best science has to offer, instead of with humors and leeches. Aren't you glad?

An anatomical illustration by Vesalius
anatomical illustrations

Preparing for Dissection

On the day that you plan to dissect, make sure you follow your lab's rules for proper attire. Never wear open-toed shoes to lab, because you never know what might fall on your foot. Use common sense about tying back long hair and avoiding dangling jewelry if you think it will get in the way.

Always wear goggles and gloves when you dissect. A lab coat is also a good idea. If you're dissecting as a group, you may want to have one designated scribe, who only wears a glove on one hand so he or she can take notes.

Some tools you will have for dissection are:

  • dissecting scissors - smaller than ordinary scissors, these allow you to cut through skin and muscle
  • forceps - kind of like tweezers, these allow you to pick up structures inside the body
  • probe - a thin tool with a blunt, hooked end that allows you to point at and move structures around without damaging them
  • dissecting pins - pin skin and organs out of the way as you go deeper
  • dissecting tray - to hold your specimen
  • rubbery mat - to hold the dissecting pins as you use them

Depending on your lab, you may also have a scalpel, a small knife. Cutting with your scalpel should be easy. If you find yourself straining to cut with a scalpel, stop immediately. Either your scalpel is too dull, or it is not the right tool for what you're trying to do. Your tools should be clean, rust-free, and sharp, which are less dangerous than dull, rusted tools.

Dissection of a rat. Note dissecting tray with mat to hold dissecting pins.
rat

When you are given your specimen, examine it carefully before making the first cut. Depending on the animal you're given, you may be able to determine its sex from its external features. You will also want to look inside the mouth. Teeth give you a pretty good idea about an animal's diet and lifestyle. Notice how the tongue is attached. For example, a mouse's tongue is attached in the back, like yours, but a bullfrog's tongue is attached in the front.

If your specimen isn't preserved in fluid, wash it with ethanol before you begin your dissection. This will prevent hairs from damaging its insides.

Inside Your Specimen

The most common mistake is to be too delicate and fussy with scissors. When you're ready to cut, go ahead and make the cut. You're not going to sew the animal back together and bring it back to life, so dig in, learn something, and have a little fun.

The structures you'll see inside may surprise you. If you're dissecting a vertebrate, most of the structures will be analogous to your own body. You'll get to see heart, lungs, liver, intestines, and stomach. If you're dissecting an invertebrate, the structures may be very different. Either way, you should have a diagram or guide to work from so you can identify the structures as you go. Pay attention to the size and location of structures. Think about what they mean to an animal's niche, or its place in the family of life.

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