Zebrafish y54 mutants show angiogenic defects in embryogenesis. (A-B) Transmitted light (A) and fluorescence microscopy (B) images of 30-hours postfertilization (hpf) Tg(fli-EGFP)^y1 y54 mutant and wild-type sibling zebrafish. (C-G) Trunk intersegmental vessel angiogenesis defects in y54 mutants. (C) Diagram of a zebrafish embryo with the red box highlighting the region shown in panels D through G and with the blue box highlighting the region shown in panels H and I. (D-G) Confocal images of trunk vessels in 30-hpf (D-E) or 54-hpf (F-G) Tg(fli-EGFP)^y1 wild-type (WT) sibling (D,F) or y54 mutant (E,G) zebrafish, showing formation of the vasculogenic dorsal aorta (DA) and posterior cardinal vein (PCV) but failure to properly form the angiogenic intersegmental vessels (arrows) in y54 mutants (lateral view, anterior to the left). (H,I) Confocal images of cranial vessels in 40-hpf Tg(fli-EGFP)^y1 wild-type sibling (H) or y54 mutant (I) zebrafish (lateral view, anterior to the left). The lateral dorsal aorta (LDA), primordial hindbrain channel (PHBC), and basilar artery (BA) are present, but the angiogenic central arteries (CtAs) fail to form in y54 mutants. Scale bars = 100 μm (D-G) and 50 μm (H-I).