[An ultrastructural study of the ependymoma cells and cells of the ventric zone and neural canal of embryonic brain].

In order to make clear the characteristics of cell differentiation in ependymoma, 12 ependymoma cases were studied with light and electronic microscopy, and the tumor cells were compared with cells of the ventric zone and neural canal from 8 embryonic brains. 10 out of 12 ependymoma cases were also studied with immunohistochemistry staining. According to the ultrastructural findings, four types of ependymoma were classified, namely, the primary neuroectodermal tumor with ependymoblast differentiation, the ependymoblastoma, the ependymoma, and the subependymoma. Some ultrastructural features, such as long intermediate junction and microrosette formation were considered as the important criterion for differential diagnosis,. Neuroendocrine granulas were found in one case of 12 ependymomas which is considered to be heterogenic in differentiation.