[Malformations induced by vitamin A administered in the young chick blastoderm]

The administration of 2250 IU of retinyl palmitate in young chick blastoderm at 4-5 HH stage brings 28% of surviving embryos and 84.5% malformed. The most frequent induced anomalies affect neural tube and/or neural crest which are the most sensible structures to vitamin A teratogenic action. The teratogenic mechanism would be produced by direct effect upon neuroblast and neural crest cells, and thus, this would cause the usual association of neural tube closure defects with facial malformations.