Vegfaa-engineered molecules block vascular development. (A) VEGFA-VEGFR2 complex highlighting VEGFA amino acids responsible for VEGFR2 interactions. (B) Schematic representation of heterodimers of dominant negative Vegfaa (red) and WT Vegfaa (white), which block Vegfr2 dimerization. (C) Brightfield micrographs of 48 hpf embryos injected with indicated mRNA in lateral views (left). Arrows point to pericardial edema. Confocal micrographs of 48 hpf TgBAC(etv2:EGFP) embryos injected with indicated mRNA in lateral views (right). Asterisks denote lack of ISVs and absent or abnormal axial vessel and brain vasculature. Bars represent 100 µm.