Ultrastructural Morphology of the Ependyma and Choroid Plexus in the African Giant Rat (CRICETOMYS GAMBIANUS)

Ependymal cells line the interface between the ventricular surfaces and the brain parenchyma. These cells, in addition to the choroid plexus, form the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) and serve important functions in the protection and regulation of brain metabolism. The African giant rat (AGR) has been used as sentinels to detect potential neuropathology arising from ecotoxicological pollutions. This study examined the lateral ventricular lining by using histology, immunohistochemistry and electron microscopy. Marked variations were observed in some regions of the ventricles which showed multi-layering of ependymal cells that differed from the typical single layered ependymal cells at the apical surface, while subependymal structures revealed indistinctive neuropil and glia following histological examinations. The ependymal cells which form the epithelial lining of the ventricles were comprised of cuboidal or low columnar cells, with the plasmalemma of abutting cells forming intercellular bridge appearing links by: tight junctions (zonula occludens), intermediate junctions (zonula adherens), desmosomes (macula adherens) and infrequent gap junctions. The choroid plexus revealed cells of Kolmer with several cilia and microvilli. The possible functional components of the ependyma and choroid plexus morphology of the AGR are discussed and thus provide a baseline for further research on the AGR brain