Histology of the persistent embryonic veins in arteriovenous malformations of brain.

Arterialized venous channels in the arteriovenous malformations of the brain represent persistent embryonic veins. The configuration of these veins resembles embryonic venous channels. Their microscopic features also resembles those of the foetal cerebral veins. The intimal liming of the persisting embryonic veins suggests the approximate age of the foetus at which the arteriovenous fistual is likely to have occurred.