Embryonic origin of holoprosencephaly: interrelationship of the developing brain and face.

Scanning electron microscopic analyses illustrate how early deficiencies in the developing neural plate (brain) relate to the subsequent development of the face. A spectrum of abnormal faces associated with variable degrees of holoprosencephaly were induced in mice by acute maternal ethanol administration during gastrulation stages of embryonic development. At the mild end of this spectrum are craniofacial features comparable to those noted in severe forms of the fetal alcohol syndrome (FAS). Complex facial malformations including those observed in FAS can be traced to a defect in development which occurs at a time corresponding to the third week of human gestation. The primary teratogenic effects of maternal ethanol exposure at the cellular level of the embryo remain to be elucidated.