Morphology of the surface of apical membranes of ependymal cells has been studied in the whole ventricular system of the brain in goat and sheep fetuses using a scanning electron microscope. The surface structure of the ependymal lining surface in fetuses of small ruminants is very similar to that in adult animals. Supraependymal cells were found only in the lower part of the third cerebral ventricle in goat fetuses, but not in sheep fetuses. In small ruminants the ependymal surface is already regionally differentiated within the end of the first half of prenatal development. Fetal ependyma of goats and sheep, unlike the adult ependyma, is characterized by a high secretory activity, which is independent of sex or age of fetuses.