Avian neural crest cell fate decisions: a diffusible signal mediates induction of neural crest by the ectoderm

During neurulation, a region of central ectoderm becomes thickened to form the neural plate which then folds upon itself to generate the neural tube, from which all neurons and glia cells of the central nervous system arise. Neural crest cells form at the border of the neural plate, where it abuts t he prospective epidermis. The neural crest is a transient population of cel ls that undergo an epithelial-mesenchymal transition. become highly migrato ry and subsequently differentiate into most of the peripheral nervous syste ms as well as numerous other derivatives. The origin of neural crest cells at the epidermal-neural plate border suggests that an interaction between t hese two tissues may be involved in neural crest formation. By experimental ly juxtaposing prospective epidermis with naive neural plate, we previously showed that an inductive interaction between these tissues can generate ne ural crest cells. Here, we further characterize the nature of this inductiv e interaction by co-culturing isolated neural plate and prospective epiderm is on opposing sides of polycarbonate filters with differing pore sizes. We find that neural crest cells are generated even when epidermis and neural plate are separated by filters that do not allow cell contact. These result s suggest that the epidermal inducer is a diffusible, secreted molecule. We discuss the developmental potential of neural crest precursors and lineage decisions that effect their differentiation into numerous derivatives. (C) 2000 ISDN. Published by Elsevier Science Ltd. All rights reserved.