Embalming is an old process. The most famous ancient examples are the Egyptian mummies, and there have been embalmed bodies dating from as early as 2145 B.C.
Granted, embalming with formaldehyde is a temporary stay of decomposition and only preserves the body for a matter of weeks.
But what if preservation could be improved? What if limbs, organs, and even full bodies could stave off decomposition indefinitely?
Gunther von Hagens, 60, inventor of the plastination process and creator of the two Body Worlds exhibits, argues that the possibilities for morphological education are vast.
Von Hagens's process - which removes bodily fluid and fats and replaces them with acetone, and then replaces the acetone with a polymer - is not new, nor are his exhibits. Body Worlds and Body Worlds II have been touring the world since the first exhibit opened in Japan in 1995. They are currently at the Museum of Science and Industry in Chicago and the Great Lakes Science Center in Cleveland, respectively. They have been to more than 10 countries on three continents.
Von Hagens created plastination in 1977 at the University of Heidelberg, Germany. The following year he founded Biodur Products, based in Heidelberg, which sells polymers, auxiliaries, and other equipment for plastination. In 1993, he also started the Institute of Plastination, also in Heidelberg.
The plastination process isn't difficult in theory. Reactive polymers like silicone rubber, epoxy resins or polyester decay very slowly, so if the body could replace the fats and liquids that bacteria decompose with such polymers, then the body could be maintained indefinitely.
But bodily fluids and reactive polymers are not chemically compatible, so some intermediary steps are necessary, explains von Hagens' Web site.
Building a body
First, the specimen is embalmed using formaldehyde. It then is dissected as desired or sawed into 3½-millimeter slices if only portions of the body are wanted.
Then, it is treated with two acetone baths. Acetone is chemically the simplest solvent of the ketone family. The first bath is cold and replaces the frozen bodily fluids with acetone. The second is a warm bath and replaces soluble fat molecules.
Von Hagens calls the next phase ``forced vacuum impregnation.'' The body is put in a chamber where pressure is decreased until the solvent boils. Once the acetone becomes gas, it is suctioned out. That creates a vacuum that causes the polymer to diffuse into the tissue.
A full body can take weeks to saturate; a body slice takes a few days.
The specimen then is cured with gas, light or heat and infused with silicone rubber or epoxy resin, depending on the polymer used and whether the sample is full-body or sheet.
The polymer used for inundation changes, depending on the sample. Silicones are used for flexible models; rigid models require epoxies, polymerizing emulsion or polyesters. Silicone rubber is used for full-body specimens, epoxies for body slices. Polymerizing emulsions turn white when cured, so they are preferable for thicker slices. Polyester yields the best results for plastinated brain.
Silicone is cured with gas, polyesters with light and epoxies with heat.
The entire process can take several weeks for sheet plastination and more than a year for a full body if the dissection is demanding, said Institute of Plastination spokeswoman Christiane Casott.
Some controversy has followed von Hagens' work. It would be unlikely that anyone could put corpses on display without complaint - unless, of course, the corpse is Tutankhamen. Sometimes von Hagens' artistic flourishes seem designed to provoke. Both Body Worlds I and II feature a pregnant woman with fetus included.
It is either morbid or fascinating, depending upon your point of view.
Other complaints stemmed from lack of female representation. Body Worlds I used to include only three full-body specimens that were female, out of 25 total. In 2002, a woman in London streaked through the exhibit in protest.
When asked about the lack of full-body female specimens, von Hagens said to the LA Alternative Press that men make better full-body models ``because women have fewer muscles than men and always die at the average of five years later.''
He also added that he did not want female bodies to be ogled by voyeurists.
Since complaints began, von Hagens made certain there were more, six, full-body females in Body Worlds II. It also should be noted that most of the individual slices and organs come from females, because most of the body donors are women.
The most acerbic criticism has not been directed toward von Hagens, but his father, Gerhard Liebchen.
Earlier this year, the Hamburg, Germany-based news magazine Der Spiegel reported that Liebchen was an SS member during World War II. Von Hagens claimed not to know that, saying his father had refused to discuss his wartime actions with his children.
More condemning, the Warsaw daily Rzeczpospolita claimed that Liebchen compiled a list of 60 Polish people who were deported to concentration camps in 1940. Both von Hagens and Liebchen denied the report, but von Hagens nevertheless fired Liebchen from his job as manager of a plastination plant in Sieniawa Zarska, Poland.
Von Hagens wrote in his catalogue, ``Society praises its living conformists and honors its deceased rebels,'' and opinions certainly are mixed regarding his work. Plastination's effect on morphology has been undeniably positive, but there is also something unsettling about Reclining Woman in the Eighth Month of Pregnancy.
Those who are uncomfortable with plastination might have to reconcile themselves to the fact that the process is not going away any time soon.
Imitation expositions like Body Explorations in Taichung, Taiwan; Bodies Revealed in Seoul, South Korea; Jintai Plastomic - Mysteries of the Human Body in Japan; and the Universe Within in San Francisco have begun appearing, and von Hagens's work keeps expanding.