Inhibition of cranial neural crest cell development by vitamin A in the cultured chick embryo.

Chick embryos at stage 8, prior to neural crest cell migration, were explanted on whole egg medium with or without vitamin A and cultured for 3 days. Sections through the head regions showed that the cranial neural crest cells had migrated into the first visceral arch in the controls but were absent from this structure in the treated embryos. These observations suggest that vitamin A inhibits neural crest cell development or migration, an effect which may in part account for the facial malformations produced by excess vitamin A.