Table 1.

Regional differences in the NVU.

	circumventricular organs	spinal cord	white matter (c. callosum)	gray matter (cortex)	hippocampus	cerebellum
capillary density	SFO: high		lower than in gray matter	higher than in white matter, increased in deeper cortical regions, AD+aging: decrease	CA3: high, CA1=white matter, aging or AD: decrease
astrocytes	GFAP-positive astrocytes: important role in preventing diffusion of blood-derived molecules outside sensory CVOs		most abundant: fibrous, high expression of intermediate filament proteins and CD44, high expression and activity of glutamate transporters	most abundant: protoplasmic, high levels of connexin-30, highly coupled	CA3: low coupling, CA1: highly coupled astrocytes
pericytes	high NG2 and PDGFRβ expression	lower pericyte coverage, ALS: pericyte loss		high pericyte coverage, AD: pericyte loss	high pericyte coverage, AD: pericyte loss and dissociation
cerebral endothelial cells	fenestrated capillaries, thinner endothelial cells, vesicles, discontinuous TJs, low expression of TJ proteins, high permeability (higher in the central regions)	reduced amounts of ZO-1, occludin, β-catenin, VE-cadherin and P-gp than in brain endothelial cells, increased permeability as compared with the brain	basement membrane=as in gray matter, CD44-negative endothelial cells, lower P-gp expression in the epileptogenic temporal lobe, increased permeability in MS	basement membrane=as in white matter, medium-sized arterioles: CD44-positive, high P-gp expression and activity	increased permeability in response to histamin, during aging, in pancreatitis or epilepsia compared to cortex, CA3: less permeable in ischemia or during aging than CA1	lower P-gp expression than in the cortex, more permeable (to bilirubin, in response to histamin) than cortical regions