Supraependymal cells occurrence in ventricular system of small ruminants. Scanning electron microscopy study.

The third cerebral ventricle ependymal lining including eminentia medians was studied by means of SEM in 20 sheep, 13 goats and one goat hermaphrodite. Supraependymal cells in addition to the usual supraependymal structures were observed. In sheep, they occurred in the infundibular low part only in females during oestrus. In goats, they were present in almost every case with the exception of male animals during the "rest" period (April). The number, topography and-to some extent--the appearance of the goat supraependymal cells were in relation to the animal's sex, and the females to the ovarian cycle phase. The supraependymal cells were found on the eminentia mediana surface only in the goats. In small ruminants, the processes of most supraependymal cells formed the ruffled membranes and only the eminentia mediana supraependymal cells--and in hermaphrodite also in the infundibular rostral part--resembled more neurons.