Fig. 4

Increased frequency of interrupted tight junctions in aged choroid plexus epithelium. A Representative TEM images of tight junctions in 2, 8 and 20 months old (m.o.) choroid plexus epithelial cells. Yellow asterisks represent junctional contact areas. B Representative immunofluorescence images of Claudin-1 (red) at 2–3 and 20–24 m.o. Zoomed inserts show high-magnification Claudin-1-immunopositive tight junctions. C Quantification of the number of Claudin-1-immunopositive intersections at 2–3, 8–12 and 20–24 m.o. n = 3–6 images per animal, 3 animals per age; One-Way ANOVA. D Quantification of junctional contact areas (%) at 2, 8 and 20 m.o. n = 30 cells per animal, 3 animals per age. Black dashed line: median; Kruskal–Wallis. **p < 0.01, ****p < 0.0001. Scale bars: 1 µm (A), 4 µm (B)