Introduction

The large variety of neural and non-neural derivatives that arise from the neural crest raises the fundamental question of how cell fates become specified during its ontogeny. In other words, what is the relative influence of intrinsic cell commitment compared to cell–cell interactions in promoting differentiation of distinct cell types.

Neural crest cells have long been implicitly considered as forming a population of homogeneous pluripotent cells that become specified to distinct lineages only after the arrest of migration and homing to their final destinations. This view would imply that local signals at the sites of homing play an instructive role in determining the precise cell types that develop. This notion has challenged investigators in the field of neural crest development to search for the existence of a stem cell from which all derivatives would arise.

The extreme opposite view of the ontogeny of the neural crest is to assume that this structure arises as, or rapidly becomes, a sum of heterogeneous cell subsets already committed to differentiate along different phenotypes. This would mean that cell fate is lineage-determined. Consequently, progressive cell divisions would specify the fate of successive daughter cells by giving rise to limited sets of crest cells. Then, upon migration, different subsets of committed cells would be expected to arrive at distinct homing sites.