Rajtová V.: The Foetal Ependyma of Cerebral Ventricles in Sheep and Goat. The Third Cerebral Ventricle in the Light and Scanning Electron Microscope. Acta Vet. Brno 68, 1999: 241-245.The study of the ependyma of the third cerebral ventricle in 35 sheep foetuses and 16 goat foetuses using a histological method, Golgi-Cox impregnation and scanning electron microscope has revealed that the 3-4 layered ependyma (between days 40 and 50 of development) changes through the pseudo-layered (up to day 130) in the typical one-layered ependyma (not long before the birth). The external morphology of foetal ependymal cells is very variable. This is related to the change of their location and gradual alteration. Remains from the foetal period can still be seen in 2-month-old lambs in the region of the upper third cerebral ventricle. In the region of the third cerebral ventricle between days 50 and 130 a co-arctation is formed, where many foetal ependymal cells are mitotically active. The surfaces of the apical membranes of proximal processes as well as the bodies of foetal ependymal cells, except for cilia, are covered with microvilli and spherical secretory protrusions.