Inductive interactions underlie neural crest formation.

The data summarized here indicate that (1) the neural crest can arise by means of inductive interaction between the neural and nonneural ectoderm; (2) initially, progenitor cells are multipotent, having the potential to form multiple ectodermal derivatives (epidermis, neural crest, and neural tube derivatives); and (3) with time, the precursors become progressively restricted to form neural crest derivatives and eventually to individual phenotypes.