“…The NVU is formed by: 1) The CSF-blood barrier, site of immunological communication between the CSF and intravascular space, which favours antigenic recognition and lymphocyte activation at this level Bigio, 1995; Nathanson & Chun, 1990a;Redzic et al, 2005; 2) The meningeal barrier, that is, the aracnoid membrane, bordering the duramater, where the CSF drains to the dural venous sinuses, the olfactory nerve and the carotid sheathsNag S. 2003; 3) the BBB, constituted by the brain vascular endothelium, regulates the entrance of molecules and supply of nutrients to the brain, as well as preserving the ionic homeostasis in the brain environment Petty & Lo, 2002; 4) the blood-nerve barrier, which surrounds the axon tangles and includes the endothelial membrane of the endoneural capillary and the perinerium Hemmer, 2004; 5) the blood-retinal barrier, formed by the retinal endothelial capillary and the retinal tissue, like BBB; 6) the blood-labyrinth barrier, which has as anatomical reference the endolymph-blood and endolymph-perilymph barriers.These capillaries are lined with endothelial cells that are joined by tight junctions and physiologically form the blood-labyrinth barrier that is essential for sensitive auditory function; and 7) the blood-spinal cord barrier -with a greater permeability than the BBBwhich communicates with the periphery through the nerve roots plexus Haukins Davis , 2005.…”