[Ultrastructural study of cerebellar medulloblastoma]

21 cases of medulloblastoma were studied by both light microscopy and electron microscopy, with observations on 10 cases of human fetal brain and neural tube as controls. Differentiation of medulloblastoma was determined according to the ultrastructural features of normal neuroblast and glial cells of human embryo. 21 cases of medulloblastoma were divided into two categories: 13 cases with no differentiation and 8 cases with differentiation in various extent (including 4 cases with astrocytic differentiation, 2 cases with neuronal differentiation, and 2 cases with both astrocytic and neuronal differentiation). In addition, surviving astrocytes and neuronal fibers were frequently observed in the tumor tissue.