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. 2009 Oct-Dec;12(4):231–237. doi: 10.4103/0972-2327.58277

Figure 2.

Figure 2

Aquaporin 4 in the brain. Several AQP4 subtypes are present in the brain. The distribution in the brain of AQP1 (blue) and AQP4 (orange) is schematically illustrated on a sagittal section of a human brain. The brain AQP shows four different expression patterns (a–d). (a) AQP4 occurs in the basolateral membrane of ependymal cells; (b) AQP1 is expressed at the apical membrane of the choroid plexus epithelial cells; (c) AQP4 is concentrated in the astrocytic end-feet, specifically in those membrane domains that abut on brain capillaries or on the 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. They are absent from neurons, oligodendrocytes, and microglia. Reprinted with permission from OP Ottersen and Macmillan Publishers Ltd: The Molecular Basis of Water Transport in the Brain. Nat Rev Neurosci. 2003 Dec;4(12):991-1001. (26), Copyright (2003)