Figure 1

Distribution in brain of aquaporin-1 (AQP1, blue) and AQP4 (orange), schematically illustrated on a sagittal section of a human brain. a: AQP4 occurs in the basolateral membrane of ependymal cells. b: AQP1 is expressed at the apical membrane of choroid plexus epithelial cells. c: AQP4 is concentrated in astrocytic end-feet, specifically in those membrane domains that abut on brain capillaries or on pia. d: AQP4 is expressed in glial lamellae of the supraoptic nucleus and other osmosensitive regions. AQP4 also occurs in non end-feet membranes of astrocytes, but at comparatively low concentrations. In the neocortex, AQP4 expression in non end-feet membranes increases from deep to superficial layers. The cerebellum shows the opposite gradient, with higher concentrations in the granule cell layer than in the molecular layer. Reprinted with permission from [20].