Microphotographs showing the distribution of claudin 3 immunoreactivity in coronal sections of the tuberal region of the hypothalamus. A: Low magnification photomontage of claudin 3 immunoreactivity (green). B–D: High magnification photomontages showing that claudin 3 is expressed in brain capillaries (B) but not in the ependymal layer of the wall of the 3V (C,D). Sections are counterstained using Hoechst (blue) to visualize cell nuclei and recognize the morphological limits of each hypothalamic structure. Scale bar = 100μm in A, 20μm in D.