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. 2005 Jan;2(1):27–43. doi: 10.1602/neurorx.2.1.27

FIG. 13.

FIG. 13.

Aquaporin-4 expression compared in the mouse BBB (A), and human brain resections (B and C). The AQP4 rabbit polyclonal immunosera were obtained from Sigma and used at a dilution of 1:500. Note that in the mouse brain (A) the AQP4 epitopes are almost all at the glial cell membrane adjacent to the basal lamina. We observed less than 2% of the AQP4 immunoreactive epitopes could be assigned to an abluminal endothelial domain in the mouse. In human brain taken from an acute pathology (traumatic injury) AQP4 is expressed at the astrocyte membranes of the glial foot process that face the microvasculature (B). AQP4 expression is also seen on astrocyte membranes of the pia (not shown). In tumor-adjacent tissue taken an astrocytoma resection, where the basal lamina has become quite thickened (C), the expression of AQP4 at the astrocyte foot process membranes contacting the basal lamina is further confirmed. In EM immunogold examination of more than 30 different resections, we found no evidence for AQP4 expression within the endothelial cell domains of the human BBB.