THE BODY WORLD

-All the bodies belonged to people who authorized the use of their bodies after their deaths for the educational benefit of medical professionals and non-professionals alike.

-The specimens are preserved by plastination - an impregnational technique carried out in a vacuum where the body tissue is saturated with special plastics.

-This technique was invented by the exhibition's creator, Professor Gunther von Hagens. Plastination lends a high degree of rigidity to the tissue, enabling bodies to be displayed in upright, lifelike poses.

THE PLASTINATION PROCESS
A process at the interface of the medical discipline of anatomy and modern polymer chemistry, Plastination makes it possible to preserve individual tissues and organs that have been removed from the body of the deceased as well as the entire body itself. Like most inventions, Plastination is simple in theory: in order to make a specimen permanent, decomposition must be halted. Decomposition is a natural process triggered initially by cell enzymes released after death and later completed when the body is colonized by putrefaction bacteria and other microorganisms. By removing water and fats from the tissue and replacing these with polymers, the Plastination process deprives bacteria of what they need to survive. Bodily fluids cannot, however, be replaced directly with polymers, because the two are chemically incompatible. Gunther von Hagens found a way around this problem: In the initial fluidexchange step, water in the tissues (which comprises approximately 70% of the human body) and fatty tissues are replaced with acetone, a solvent that readily evaporates. In the second step, the acetone is replaced with a polymer solution. The trick that first proved to be critical for pulling the liquid polymer into each and every cell is what he calls "forced vacuum impregnation." A specimen is placed in a vacuum chamber and the pressure is reduced to the point where the solvent boils. The acetone is suctioned out of the tissue at the moment it vaporizes, and the resulting vacuum in the specimen causes the polymer solution to permeate the tissue This exchange process is allowed to continue until all of the tissue has been completely saturated—while a matter of only a few days for thin slices, this step can take weeks for whole bodies.

The second trick is selecting the right polymer. For this purpose, "reactive polymers" are used, i.e., polymers that cure (polymerize) under specific conditions, such as the presence of light, heat, or certain gases. Their viscosity must be low, i.e., they have to be very thin liquids; they must be able to resist yellowing; and, of course, they must be compatible with human tissue. The polymer selected determines the look and feel of the finished specimen.