Brain Development in Normal and reeler Mice: the Phenotype

Abstract

In spite of close scrutiny during the last decades, most of the mechanisms that govern neural development remain unknown. Yet, in addition to an obvious theoretical interest, understanding of these principles is requisite to the effective management of human brain malformations and mental retardation. Present views on the development of the central nervous system can be schematized as follows. The CNS derives from the embryonic epiblast. An initial neural plate becomes hollow (neural groove) and closes into the neural tube. As it does so, it sends into the mesoderm a contingent of cells known as the neural crest. The cavity of the neural tube gives rise to the ventricular system, whereas the neural parenchyma derives from its walls. It is worth pointing out that the development of the CNS is largely intra-epithelial and thus different from the development of most other organs. Of course, this does not imply that interactions between the neural epithelium and the mesoderm are negligible. For example, the observation that Cajal-Retzius cells keep contact with the basal lamina by radial processes may be relevant to their function (Derer 1979).