THE ROLE OF VITAMIN-A IN THE DEVELOPMENT OF THE CENTRAL-NERVOUS-SYSTEM

We describe here the defects that arise in the central nervous system (CNS) of quail embryos when they develop in the absence of vitamin A. It has been assumed that because of the effects of excess vitamin A an d its metabolites, particularly retinoic acid (RA), on the CNS they ar e involved in various aspects of CNS development. We show that this is indeed the case, because these deficient quail embryos have three def ects in their CNS. First, the posterior hindbrain fails to develop bec ause the cells fated to form this part of the CNS in the very early em bryo die by apoptosis, Second, the neural tube fails to extend neurite s into the periphery both in vivo and in vitro. Third, the neural cres t cells throughout the embryo die by apoptosis. These results demonstr ate a crucial requirement for vitamin A in CNS development.