Ultrastructure of oligodendrogliomas.

The study of 18 oligodendrogliomas shows a number of characteristics which indicate a common hypothelial stem cell. The main cytologic characteristics are: a) high number of mitochondria, frequently atypical; b) polygonal crystalline structures in the cytoplasm in most of the tumors studied, and c) cytoplasmic microtubuli. None of these characteristics can be considered as pathognomic for the oligodendrogliomas. However, rows of folding cell processes represent a fundamental structural principle of all oligodendrogliomas and since they have not been found in any other brain tumor and may be regarded as an inherent and specific characteristic of the oligodendroglial group.