Ependymal explants from the lateral ventricle of the adult bovine brain: amodel system for morphological and functional studies of the ependyma

By gently scraping off the surface of the lateral ventricles of adult bovin e brains, we obtained sheets containing the ependymal layer and some attach ed subependymal cells. Explants were cultured in serum-free medium or in tw o media enriched with 20% fetal calf serum or 20% adult bovine cerebrospina l fluid, and processed for different time intervals from 4 h to 60 days. Fo r characterization of the ependymal cells we used antisera against S-100 pr otein. vimentin and glial fibrillary acidic protein (GFAP). For comparison, the ependyma of adult bovines and of fetuses from days 60 to 120 post coit um was studied in situ. The adult ependyma consisted of a ciliated, cuboid cell monolayer with short basal processes; it displayed S-100 immunoreactiv ity but only scarce deposits of vimentin and no GFAP. The fetal ependyma ha d the appearance of a pseudostratified epi thelium with elongated nuclei an d basal processes containing S-100 and vimentin from day 80 post coitum and GFAP from day 100 post coitum, In explants, no differences were seen betwe en the three culture media; the ependyma became pseudostratified, developed basal processes and showed increasing amounts of S-100 and vimentin first, and subsequently also GFAP. These changes were concomitant with the onset of mitotic activity in the subependymal layer leading to the production of numerous cells. The morphological and immunocytochemical features of ependy mal cells in cultured explants resembled those of fetal ependyma, Our resul ts indicate that the culture of ependymal explants from adult bovine latera l ventricles is an useful model system for morphological and functional stu dies of the ependyma and for the analysis of cell proliferation in the sube pendymal layer.