ANATOMY OF THE CIRCLE OF WILLIS IN 3 CASES OF HUMAN FETAL SYNOPHTHALMIC HOLOPROSENCEPHALY

In three human fetuses with synophthalmic holoprosencephaly (8, 14, 23 weeks post conceptionem) the circle of Willis was studied using seria l histological sections and computer aided three dimensional reconstru ction methods. This structure was abnormal in all cases. In two cases the anterior communicating arteries were absent. In all cases the ante rior cerebral arteries could not be found. One case showed an incomple te circle with no posterior communicating artery. The results indicate that the malformation of the circle of Willis reflects the malformati on of the brain.