[Ependyma in sheep. 5. Ependymal lining of the cerebral ventricles using scanning electron microscopy]

In 10 ewes and 10 rams the ependymal surface of the brain ventricular system was examined by the scanning electron microscope. The surfaces of the ependymal cells in the upper third of the suprachiasmatic and infundibular regions of the III-rd, partly in the lateral ventricles are covered with dense cilia. A great part of the ventricular surface is covered with microvilli and thin cilia, which are formed into bundles. At certain sites e.g. on the cornu ammonis, suprachiasmatic and infundibular recesses, on the bottom of the aquaeductus mesencephali small foci without microvilli and cilia ("bare") can be observed. In the upper half of the suprachiasmatic region some of the cilia have button-like and in the cornu temporale in the lateral ventricle club-like terminations. The building of the ependymal surface in the infundibular recess in sheep depends on the sex; in the ewes it altered in correlation to the stage of the ovarian cycle and in the rams according to the season. Supraependymal cells were found only in ewes during estrus, in rams they were not found. According to the external morphology the supraependymal cells are divided into three groups.