Evidence of very early neuronal migration from the olfactory placode of the chick embryo

Cell migration from the olfactory neuroepithelium is a very peculiar phenom enon in the development of the nervous system. In this paper, we provide ev idence that. in the chick embryo, migration of cells from the olfactory neu roepithelium begins earlier than previously reported, namely at the same ti me as the first olfactory placode differentiation, that occurs several hour s before the superficial ectodermal invagination that gives rise to the olf actory pit, Moreover, we provide evidence that very early migrating cells e xpress the HuC/D RNA-binding protein antigen. a specific neuronal marker. These observations refocus our knowledge on the very first developmental st ages of olfactory neuroepithelium. (C) 2001 IBRO. Published by Elsevier Sci ence Ltd. All rights reserved.