ptc1;ptc2 mutants exhibit precocious vessel sprouting from the posterior cardinal vein. Confocal images of developing trunk vasculature in Tg(fli1a:EGFP)y1/+ (A,C,E) and Tg(fli1a:EGFP)y1/+;ptc1;ptc2 embryos at 27 hpf (B,D,F); anterior is left, posterior right. (A) Normal trunk vasculature. Highlighted area is shown in panel C. (B) Endothelial connections between the DA and PCV were present in Tg(fli1a:EGFP)y1/+;ptc1;ptc2 embryos (gray arrowheads), and ectopic vessel sprouts arising from PCVs were present (B,D white arrowheads). Highlighted area is shown in panel D. 3-Dimensional reconstruction: transverse plane of embryo shown in panels A, C, and E and embryo shown in panels B, D, and F) show the sprouting capacity of ECs in the PCV region in ptc1;ptc2 mutants (white arrowhead).