Sarcoma 180 has been studied with the electron microscope. Desmosomes have been demonstrated at the intercellular junctions in the tumor cells. The desmosome consists of a plate-like cytoplasmic condensation on which bundles of tonofilaments end. The intercellular space at the desmosome level may show a dense, fibrillar material. The presence of desmosomes and tonofilaments demonstrates the epithelial nature of this tumor and thus its identification as a carcinoma. The abundance of peri- and interchromatin granules, the nucleolar persistence during mitosis, and the presence of dense bodies either close to mitotic chromosomes or in the cytoplasm during nuclear reconstruction, as well as other features of the tumor cells, are briefly described.
This work was supported in part by ASARCA, Asociación Argentina del Cáncer. Presented at the “Primeras Jornadas de Oncología.” Instituto de Oncología “Angel H. Roffo.” November 24 to 25, 1972, Buenos Aires, Argentina.