Ependymomas of childhood. II. Electron-microscopic study.

Electron-microscopic study of various histological types of ependymoma has shown three basic types of cells. One type of cells has features typical of normal ependymal cells, the second type consists of cells resembling normal or reactive astrocytes, and the third type of cells is undifferentiated. The three types of cells are present in various proportions in every tumor. Generally speaking, the astrocyte-like cells are more frequently encountered than the ependymol cells. The undifferentiated cells are seen, in small numbers, in all forms of ependymoma but they are the dominant cell type in the ependymoblastomas.