Anti-BMP10 treatment disrupts vascularization of the retina of Bmp9-KO mice. Visualization of blood vessels by isolectin B4 (iB4) staining of retinas at P5 from Bmp9-KO (A-B) or WT (C-D) mice treated with PBS or anti-BMP10 antibody (15 mg/kg) injected at P1 and P3. (E-F) Bar graphs show the relative distance covered by the vascular plexus calculated as the ratio of the vascular radius over the retinal radius in percentage in Bmp9-KO mice (E) and in WT mice (F). (G-H) Higher magnifications of the retinas show that anti-BMP10 treatment in Bmp9-KO mice lead to larger and multilayered blood vessels (see also z scan in panels I and J). Panels A, B, E, G, H, I, and J show data from 4 litters containing 12 PBS-treated Bmp9-KO pups and 7 anti-BMP10 treated pups. Panels C, D, and F show data from 2 litters containing 6 PBS treated WT pups and 6 anti-BMP10 treated pups. Error bars show SEM. **P < .01 versus PBS group. (A-D) Scale bar = 200 μm. (G-H) Scale bar = 20 μm.