Extroversion of cerebral hemispheres in a full term human foetus.

Extroversion of the cerebral hemispheres and a posterior intestinal fistula are described in a male foetus with single umbilical artery and craniorhachischisis. The paper has distinction of describing for the first time the cerebral extroversion in a full term human foetus. At this stage of development, the everted cerebral hemispheres, after having proliferated exuberantly to a considerable size present a disorganised appearance which would vary in every case of this type. However, the lateral ventricles are still visible, structures comparable to thalami and choroid plexus can be made out and the vascular masses with large blood clots seen in anencephaly are minimal. That the posterior intestinal fistula represents persistence of an accessory neurenteric canal is discussed. The neural and neurenteric defects in the specimen described here are possibly due to abnormal arterial pattern in the caudal half of the body, imposed by single umbilical artery.