Middle interhemispheric fusion: an unusual variant of holoprosencephaly.

Abstract

Middle interhemispheric fusion may be considered as a variant of holoprosencephaly. It is suggested that the mesenchyme formed by the prechordal plate, notochord, and neural crest play an important part in the early development of the brain and that anomalies of the mesenchyme underlie this disorder as well as other forms of holoprosencephaly.