HISTOLOGICAL INVESTIGATIONS ON THE TYROLEAN ICE MAN

The 5,200-year-old Tyrolean Ice Man discovered in 1991 in the Otztal A lps is the world's most ancient known human glacier mummy. Histologica l investigation was aimed at 1) optimizing specimen preparation and 2) documenting the preservation state of (sub)cellular components. Minut e pieces of frozen tissue were removed endoscopically from rib bone an d cartilage, major blood vessels, oral cavity and alimentary tract, li ver, spleen, diaphragm, respiratory system, femoral muscle and nerve, sympathetic trunk, brain, and skin. Double fixation with glutaraldehyd e followed by osmium tetroxide and embedding in Epon/Araldite epoxy re sins proved to be the method of choice for both light and transmission electron microscopy combined with classical histochemistry. In partic ular, mild evacuation of the desiccated tissue was determined to be es sential to ensure homogeneous infiltration with fixatives and resins; as a result, sections of excellent quality could be obtained with any kind of sample. With regard to the preservation degree of (sub)cellula r components, distinct tissue-specific patterns were observed. There w ere highly intact skeletal and connective tissues proper, however, mos t interestingly, there were remarkably intact nervous tissue component s as well. By contrast, epithelial, muscle, and reticular connective t issues as well as blood had generally disintegrated due to autolysis, freeze/thaw damage, and adipocere formation. For a tentative interpret ation of these patterns, we considered general aspects of cryopreserva tion, such as physicochemical properties of subcellular constituents a nd tissue physiology. (C) 1998 Wiley-Liss, Inc.