RELATION OF ABNORMAL COLLECTIONS OF CELLS IN POSTERIOR MEDULLARY VELUM OF CEREBELLUM TO ORIGIN OF MEDULLOBLASTOMA

Abstract

The external granular layer of the cerebellum, which makes its appearance in early fetal life, contributes to the growth of the cerebellum and then disappears within twenty months after birth, is composed of cells which resemble the cells in the medulloblastoma. This similarity has led to the theory that the cells of the external granular layer do not disappear in certain regions as quickly as in others and that the persistence of some of these cells is the origin of the medulloblastoma. In another study (to be published elsewhere¹) of the same material that forms the basis of this investigation, in which we gave especial attention to the disappearance of the external granular layer and the growth of the molecular and internal granular layers of the cerebellum, we made the following observations: The rate of decrease in width of the external granular layer does not differ significantly in the