Blastula stage specification of avian neural crest

Abstract

Cell fate specification defines the earliest steps towards a distinct cell lineage. Neural crest, a multipotent stem cell population, is thought to be specified from the ectoderm, but its varied contributions defy canons of segregation potential and challenges its embryonic origin. Aiming to resolve this conflict, we have assayed the earliest specification of neural crest using blastula stage chick embryos. Specification assays on isolated chick epiblast explants identify an intermediate region specified towards the neural crest cell fate. Furthermore, low density culture suggests that the specification of intermediate cells towards the neural crest lineage is independent of contact mediated induction. Finally, we have validated the regional identity of the intermediate region towards the neural crest cell fate using fate map studies in blastula stage chick embryos. Our results suggest a model of neural crest specification at blastula stage, with restricted ectoderm and mesoderm capacities.