Avian neural crest-derived neurogenic precursors undergo apoptosis on the lateral migration pathway

Neural crest cells of vertebrate embryos disperse on distinct pathways and produce different derivatives in specific embryonic locations. In the trunk of avian embryos, crest-derived cells that initially migrate on the latera l pathway, between epidermal ectoderm and somite, produce melanocytes but n o neuronal derivatives. Although we found that melanocyte precursors are sp ecified before they disperse on the lateral pathway, we also observed that a few crest-derived neuronal cells are briefly present on the same pathway. Here, we show that neuronal cells are removed by an episode of apoptosis. These observations suggest that localized environmental factor(s) affect th e distribution of fate-restricted crest derivatives and function as a 'proo f-reading mechanism' to remove 'ectopic' crest-derived cells.