Characterization of a zebrafish mutant that affects the formation of the lymphatic vascular system. A, Gross morphology of the Ly02-512 mutant. The mutant embryos appear without major macroscopic defects or developmental delay, and form a swim bladder at 5 d post-fertilization (dpf). However, closer examination shows abnormalities in the jaw (arrowhead), and the embryo displays edema around the heart, eye, and intestine (arrows). B, Analysis of the vasculature in a fli1a:GFP; flt1enh:RFP transgenic background, highlighting arteries (red). Note the normal overall patterning of the blood vasculature despite the higher proportion of intersegmental arteries in the mutant embryo. C, Mutant embryos lack all or most aspects of the thoracic duct (TD), which in wild-type siblings is positioned just ventral to the dorsal aorta (DA; white arrows in C and D) but is absent in mutants (asterisks). D, Rhodamine dextran injection into the cardinal vein shows normal blood circulation in Ly02-512 mutants.