Abstract

Despite the significant portion of telencephalus is missing in most anencephalics it is fairly cosistent finding that eye these subjects are well formed and preserved. The eye balls were morphologically normal including the retina which is the direct extension of developing telencephalus. In this sense, optic nerve which is merely a white matter tract interconnecting the eye ball to cerebral hemisphere are expected to be in an interesting position of existence. Because cerebral hemisphere is regularly missing in contrast to iconsistently present eye ball. In this communication we studied the optic nerves in anencephalics to determine the spectrum of preservation and also the detailed histology of the remaining optic nerves. Both optic nerves together with dural sheath were dissected from orbit and cranial vault and were serially cut in transverse. There was a rather abrupt discontinuation of optic nerve fibers toward the course of optic chiasm. These findings strongly support the view that the absence of telencephalon in anencephaly is not a primary termination failure but a secondary destruction of cerebral hemisphere during intrauterine life.