VE-cadherin function-blocking antibody treatment disrupts vascular morphogenesis in the 7.8-dpc allantois explant culture model. (A-D) PECAM-immunolabeled allantois explants from 7.8-dpc embryos following 18 hours of culture in control medium (A,C) or BV13 monoclonal antibody (24 μg IgG/mL; B,D). Arrows (C, control; D, BV13-treated) indicate PECAM deposition at cell-cell junctions. (E-F) DIC images of the same regions of the explants depicted in panels C and D, respectively. Arrowheads in panels D,F indicate a PECAM⁺ cluster of cells resulting from BV13 treatment. (G-H) PECAM-immunolabeled allantois explants from 7.8-dpc embryos following 18 hours of culture in Fab fragments of BV13 antibody (24 μg IgG/mL; G) or BV14 antibody (24 μg IgG/mL; H). Bars equal 50 μm. Panels A, B, G, and H are confocal images; C and D, epifluorescence images; and E and F, DIC images.