The avian embryo, a model for the role of cellular interactions in development; the example of neural crest-derived pigment cells

We have been using neural crest development as a model for understanding the molecular basis of cell migration and lineage diversification during embryogenesis, and to explore the roles of inherited information and cell-to-cell interactions in this process. Techniques allowing the migratory crest cells to be followed during the entire developmental period have given a significant impetus to research carried out in the avian embryo. One of the most striking results to arise from this experimental approach is probably the demonstration of the considerable importance of the developmental relationships existing between the neural crest cells and the embryonic tissues in which they migrate and differentiate. Concerning the nature of these interactions, much progress has been recently provided by the combination of molecular biology, experimental embryology and in vitro cell culture studies. As an example of the role of extrinsic cues in cellular specification, we review here several lines of investigations which have led to the identification of two ligand-receptors i.e., Steel/c-kit and endothelin3/endothelin receptors as crucial signals for regulating the early developmental stages of neural crest-derived pigment cells.