Figure 1

Immunohistofluorescence analysis of claudin-1 and claudin-5 in E19 rat brain. A and B: forebrain. The vascular network is labeled by claudin-5 antibodies (red), while both the third and lateral ventricles choroid plexuses are labeled by claudin-1 antibodies (green). C and D: Hindbrain. The cerebellar and medullar vascular networks are labeled by claudin-5 antibodies, while both the central and lateral parts of the fourth ventricle choroid plexus are labeled by claudin-1 antibodies. Note the intercellular junction labeling of the meningeal vessels (long arrows) such as that located in the ambient cistern (enlarged in B). Claudin-1 immunoreactivity at the periphery of choroidal epithelial cells is clearly seen in the enlarged fourth ventricle area (D). Claudin-5 immunoreactivity is found in penetrating choroidal vessels (arrowhead), but not in the terminal vascular loops of choroidal villi. The ependyma (Ep) is devoid of staining. Other abbreviations: AmbCi: ambient cistern, LV, 3 V, 4 V: Lateral, third and fourth ventricles, respectively.