THE MEDULLOBLAST AND THE MEDULLOBLASTOMA

Abstract

The interest of neuropathologists in the cytogenesis of the nervous system became enhanced by the realization that gliomas contain cells resembling those seen in the brain during normal embryonic life. Yet few embryologic studies have been made to substantiate this analogy, least of all on human cytogenesis. The term medulloblast was coined by Bailey and Cushing¹ to identify the type cell of the medulloblastoma. It was defined as a bipotential undifferentiated element analogous to the "indifferent cell" described by the embryologist Schaper.² The "indifferent cell" described by Schaper was an apolar element occurring ubiquitously in the growing central nervous system and capable of the dual function of neurogenesis and gliogenesis. Few subsequent embryologists have been able to identify such a cell, and its existence has come to be regarded as hypothetic (Bailey³ and Penfield⁴). This study of human embryos and fetuses establishes that medulloblasts exist, but