Résumé
Specimens of skin, skeletal muscle, adipose tissue, brain, peripheral nerve and catilage were taken from 6 cadavers (divided into 2 groups) perfused and embalmed with formalin. 90 pieces of the above-mentioned tissues were taken in different times and the paraffin sections were stained by routine HE. Electron microscopic observation was made from some skin and skeletal muscle specimens, and histochemical methods were used to demonstrate DNA, RNA, keratin(-SH, -SS), fatty acids and calcium in some skin materials. Loyez stain method for myelin sheath was applied to some brain and nerve sections.1. Skin tissue: In both group A and B, 83.3% and 78.9% of skin materials were appraised as grade I and II (excellent and good) respectively. The morphological changes appeared mainly as karyopyknosis of the epidermal cells and shrinkage of the secretory part of the sweat glands. Most of the skin tissues of the corpses perfused 3～4 hrs after death were well preserved, only 8.3% being in grade Ⅲ (moderate). On the other hand, 43% of skin materials taken from those perfused 30 hrs after death were in grade Ⅲ. Ultrastructurally, the shape of the epidermal cells and their adhensions still remained intact, but karyopyknosis or chromolysis and autolysis of most of the cytoplasmic membraneous structures were found. In those cadavers preserved for less than one year, there was no evidence of progressive changes in microscopic and submicroscopic structures of the skin. The tonofillaments and desmosomes were still kept well in those specimens preserved for many years, and their presence may be the cause of maintaining cell integrity. Histochemically, mercapto-reaction of keratin was kept stable and found to be well shown even in old samples of skin, but the disulfide reaction usually showed marked fading with time, probably due to exofolition of the stratum corneum. However, this reaction was well shown in the hairs and not weakened for many years.2. Fat tissue: Hydrolysis of lipid substances of subcutancous fat and sebaceous gland, as shown by the presence of fatty acid, was found in the corpses preserved even as short as half a year.3. Skeletal muscle: The preservation state of the skeletal muscle was also dependent on the complete perfusion in time. The structure of the muscle fibers was generally worse preserved than that of the skin as shown in severe myolysis. Since stagnation of the small blood vessels frequently accompanied myolysis, obstruction of microcirculation which prevented the permeation of fomalin into the muscle tissues may be the cause of rapid myolysis. The ultrastructural changes of the muscle fibers were the same as those of the epidermal cells. In all specimens even as old as 30 years, two types of myofillaments were well preserved, and bands could be seen distinctly.4. Nervous tissue: The brain tissues were well preserved in those corpses that were perfused shortly after death, but the peripheral nerves usually showed severe autolysis, obviously it is due to the same reasons as those for myolysis.5. Cartilage: The structural changes of cartilage after death were slow and all specimens of cartilage were well preserved.