Spatial and temporal expression of claudin-5 in the developing BBB. Tg(flk1:EGFP) embryos at 2 dpf, 2.5 dpf, and 3 dpf were stained with a monoclonal claudin-5 antibody. Confocal images of whole mount embryos were analyzed for claudin-5 expression (red) (A-E and H-M; Alexa Fluor 568 labeled secondary antibody) in developing blood vessels (green) (A'-E' and H'-M'; EGFP labeled vascular endothelial cells; F&G, merged pictures). All the samples are oriented with anterior to the left. A-E and A'-E', lateral views; other panels, dorsal views. Scale bars: 50 um.