Structural patterns and histological behaviour of experimental sarcomas. II. Ultrastructural cytology.

In continuation of our investigations on methylcholanthrene-induced rat sarcomas, in analogy to light microscopical results, various cytological differentiations could be demonstrated by the electron microscope. Some tumour cells are comparable to the cellular counterpart in normal connective tissue, whereas most of the tumour cells show various series of cytological traits of different types of normal connective tissue cells simultaneously. The vast majority of tumour cells exhibited characteristics of fibroblasts and histiocytes coincidently. However, classical fibroblasts and histiocytes were seldom present. One part of the tumour cells showed structural features as known from so-called myofibroblasts and smooth muscles cells. Furthermore, vasoformative potencies of sarcomas with imitation of endothelial and pericytic cells must be emphasized. With respect to the histogenesis of these sarcomas possible origin from the microvasculature is discussed.