AN ULTRASTRUCTURE OF CELL-DEATH IN A PIG MELANOMA

A form of cell death was studied electronmicroscopically in the regres sive stage of 4 pigs melanoma. Basically, four types of cells were fou nd: macrophages, large granular lymphocytes, melanocytes, and melanoph ages. Morphological changes in cell death were most frequently observe d in the cytoplasm of tumour cells, in the form of dilatation of granu lar endoplasmic reticulum and/or vacuolation of cytoplasm close to the cell surface together with crater-like cavities. Rarely, condensation and margination of nuclear chromatin were observed without lesions in the cytoplasm. The above lesions are typical sings of cells undergoin g apoptosis.