[Ultrastructural characteristics of the specialized ependyma of the 3d cerebral ventricle in rats].

The ultrastructure of the specialized ependyma of the third cerebrals ventricle was studied in males of albino Wistar rats, 160--180 g of weight. The ependyma lining the inferolateral walls (alpha-tanycytes) was found to differ ultrastructurally from that of the floor of the third ventricle or of the median eminence (beta-tanycytes). These differences are assumed to reflect a specific functional differentiation of the different types of tanycytes. Various types of microvesicles and a system of peculiar membranous cavities are described in the alpha-and beta-tanycytes. These structures are supposed to be associated with the transport and secretory function of tanycytes.