In a basement laboratory room of the sprawling University Hospital is a doctor in surgical scrubs and mask, hunched over a leg, working methodically with a scalpel. Three students sit across the room from him, watching intently as he scrapes deposits of fat tissue from in between the muscle, tendon and bone of the dissected limb and places it on a steel tray beside him.
The doctor doesn’t worry about anesthesia or monitoring vital signs – the leg is no longer attached to any person. The leg won’t be used for walking anymore, but instead it will be preserved as an anatomical specimen; it’s in the process of becoming plastinated.
The art and science of human body preservation has been a work-in-progress for thousands of years and continues at the University with a technique called plastination, which preserves a body with plastic.
The most famous ancient preservers were the Egyptians. They used natural chemicals to accelerate the dehydration of body tissues that, in conjunction with the naturally dry environment, helped preserve the body for the afterlife. Other ancient preservers include the Chincohorro tribe in Chile, whose preservation techniques predate Egyptian ones by thousands of years.
But the modern-day technique of tissue plastination, has only recently emerged. Developed in the 1970s by Gunther von Hagens, a German anatomist, the method he pioneered picks up where the Egyptians and Chinchorros left off, but for a very different purpose: clean, odorless long-term preservation of human tissue for use in anatomical study and education.
The problems with the more simple and ancient art of dehydrating tissue is that it will eventually decay in even the most habitable environments and, in the end, it doesn’t really look like its former natural self.
And the problem with wet-chemical fixation – such as that creepy two-headed pig floating in a formalin-filled jar on the shelf above your high school biology teacher’s desk – is that it not only smells terrible and makes a mess, but also causes specimens to lose their color and texture in time, making it difficult to discern fine tissue structures.
The answer to both of these problems is known to anyone who has seen the movie “The Graduate”: plastics.
But before getting into that, there first needs to be a body and the know-how. The University is one of the few places in the world to have a human plastination facility.
It was established in 1989 by anatomy Prof. Roy Glover, and has been directed since 2004 by anatomy Prof. Ameed Raoof. The mission of the Plastination Laboratory, according to Raoof, is “to promote the education of anatomical studies.”
The University receives bodies through donations from its Anatomical Donation Program.
Those agreeing to be “permanently preserved” are the candidates for the plastination process in the Plastination Laboratory.
According to Raoof, a typical plastination procedure starts when the body is received from a funeral home and injected with a large dose of formalin, a chemical that replaces body fluids within the tissues and keeps it from decaying. This is necessary because it can take up to eight weeks for a full dissection of the body.
The extent and method of the dissection depends on the educational need: be it a leg for a kinesiology class or a cerebrum for a neuroanatomy laboratory.
Fat, which has high water content and any other undesirable tissues – like membranes surrounding the cerebrum – are carefully removed.
Once the specimen has been dissected to the anatomist’s satisfaction, the tissue is soaked in a series of successively graded concentrations of chilled acetone, an organic solvent characterized by a low boiling point.
The chilled acetone replaces body fluids and the formalin to dehydrate the tissue, similar to the concept of the Egyptians use of natural natron salts. This takes anywhere from two days to three weeks, depending on the size of the specimen, and then it is ready for the plastination chamber.
The acetone-soaked tissue is then set in a pool of liquefied plastic, and the air within the chamber is evacuated with a vacuum pump.
For those who haven’t let the “ideal gas law” evaporate from their minds, a drop in pressure will cause a corresponding drop in the temperature needed to reach a boiling point of a liquid.
Here, the acetone evaporates from the tissue allowing the liquid plastic to fill its place within the tissue structure.
Raoof said that the introduction of plastic into the tissues can take up to eight weeks, once again depending upon the size and density of the specimen and plastination method used.
Then it is prepared and painted appropriately for the study it is intended for. The painting is to either make up any tissue discoloration or to add information to the model – such as making arteries red and veins blue.
There does not seem to be any limit to what can be created – in a rack of finished specimens within the Plastination Lab, there lay a stack of half-inch-thick cross-sectioned torso slices next to a negative impression of the interior of a lung.
Will plastinated specimens become the status quo and completely replace tissue specimens bottled in liquid formalin? Raoof said that medical school curriculum will always require students to dissect real body parts, and not just plastinated body tissue.
Plastination is just the latest chapter in the ongoing saga to develop the perfect method of body preservation. The reasons might have changed drastically in a historical context, but it seems certain that efforts to preserve human bodies will persist.