The neural crest in abnormalities of the face and brain.

Available evidence indicates that neural crest cells, which originate from ectoderm at the neural plate margin, form the skeletal and connective tissues in the face and portions of the cranium. Common origins may thus account for some brain-eye-face malformation complexes such as arhinencephaly. These are thought to involve deficient crest-cell formation which particularly affects frontonasal derivatives. In contrast, the more caudal maxillary process and visceral arch derivatives seem to be more affected by defective crest migration. Also considered are malformations possibly resulting from defects in crest-cell proliferation and differentiation.