Growth in rat of a sarcoma derived from rat kidney cells transformed in vitro by SV40

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.

The ultrastructure of tumours derived from spontaneously transformed tissue culture cells

The ultrastructure of 16 tumours derived from spontaneously transformed cell lines established from young and old C57 and C3H mouse organs is described. Three types of tumour were found: myxoid (fibrosarcomatous), consisting of cells with long processes and much interstitial material; leiomyomatous, consisting of a bundle of smooth muscle-like cells with less interstitial material; or epithelial-like consisting of closely packed round cells with little interstitial material. The cell types in the tumours were similar to those found in the tissue culture cell lines from which they were derived.