(A and B) Whole-mount PECAM-1 IHC in OIR retinas of C57BL/6 mice at 24 hours (A) and 72 hours (B) after intravitreal injections of recombinant proteins (1 μl volume at 2 μg/μl concentration) at P14. Sema3E did not affect intraretinal projections of endothelial filopodia at P15 (A), but did suppress extraretinal vascular outgrowth at P17, leading to the restoration of normal vascular architecture in ischemic retinas (B). VEGFR1-Fc completely suppressed endothelial filopodia projections (A), resulting in extensive ischemic retinal areas (B). Scale bars: 10 μm (A); 100 μm (B). (C) Quantification of the number of extraretinal vessels, capillary density in the vascularized area, and unvascularized retinal area at 72 hours after injection of 1 μl recombinant proteins at P14. The protein concentrations (μg/μl) are indicated in the parentheses. P values were calculated by comparison with the Control Fc. Error bars represent SEM; ***P < 0.001, **P < 0.01.