On the cover: Vascular tight junctions of skin blood vessels of embryonic day 14.5 embryo stained for Zonula occludens-1 (red), endothelial cells (CD31/PECAM-1; green), and nuclei (DAPI; blue). Tight junctions between adjacent endothelial cells are intact, and no evidence for tight junctional permeability was found in conditional c-Myc overexpressing embryos. See related article, page 1151.