THE SCHWANN-CELL PRECURSOR AND ITS FATE - A STUDY OF CELL-DEATH AND DIFFERENTIATION DURING GLIOGENESIS IN RAT EMBRYONIC NERVES

We have characterized a cell, the Schwann cell precursor, that represe nts a distinct intermediate differentiation stage in the process by wh ich Schwann cells are generated from neural crest cells. The Schwann c ell precursor shows radical differences from Schwann cells which inclu de death regulation, antigenic phenotype, pattern of cell-cell interac tion, migratory behavior, and morphology. In the nerves of the rat hin d limb, Schwann cells are irreversibly generated from these during a b rief period, essentially embryonic days 15-17. We also provide evidenc e that the survival of Schwann cell precursors is regulated by neurons and identify basic fibroblast growth factor as a potential key regula tor of apoptosis in Schwann cell precursors and of precursor to Schwan n cell conversion. These findings have implications for our understand ing of gliogenesis in the peripheral nervous system.