vegfaa is required for arterial differentiation. (A) Confocal micrographs of 48 hpf TgBAC(etv2:EGFP) WT sibling and vegfaa^bns1 mutant embryos in lateral views. Bar represents 100 µm. Asterisks denote lack of ISVs, axial vessel, and reduced CtA sprouting. (B) Brightfield whole-mount in situ hybridization of efnb2a expression in 26 hpf embryos in lateral views. Arrow points to a reduction of efnb2a expression in the DA region. (C) Confocal micrographs of 26 hpf TgBAC(etv2:EGFP) WT sibling and vegfaa^bns1 mutant embryos in transverse views. Asterisk denotes lack of vessel in DA region. Bar represents 30 µm. (D) Cartoon representations of a cross section through the zebrafish trunk. A, dorsal aorta; NC, notochord; S, somite; V, posterior cardinal vein.