The fine structure of cells in astrocytomas of various grades of malignancy.

87 gliomas were studied electron microscopically. 9 tumors were excluded from the series as mixed gliomas. The ultrastructure of the cell cytoplasm was considered particularly relevant for the present study. According to the electron density and arrangement of organelles and cytofilaments 4 basic cell types I (Ia), II, III, and IV are defined. An attempt is made to scatch the development of immature glial cells in slowly grown tumors as well as their dedifferentiation in 2 cell types V and VI in malignant growths.