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Even though a major German encyclopedia (the 19th edition of the
Brockhaus Encyclopedia, 1992) indicates that the word "Plastination" is
derived from the Greek (from plassein = to shape, to form), the term
is, in fact, a creation of Gunther von Hagens. He coined the term
because "plastification" already had a fixed meaning in the field of
polymer chemistry, and the expression used in the original patents of
1977/78 ("Polymer Impregnation of Perishable, Biological Specimens”)
was not terribly catchy and was utterly inadequate for popularizing the
new technology, particularly abroad. The following will provide an
explanation of how Plastination works. We will first present the
process in a general, comprehensible manner; for those with an
interest, we will then go into more detail regarding the chemicals and
chemical processes used.
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.
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The method of Plastination has been protected by a number of patents in
Germany, Great Britain, Belgium, South Africa, Austrai and the United
States.
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