Fig. 6

hand2 promotes proper vein formation.

(A–I) In situ hybridization depicts expression of mrc1a (A–C), flt4 (D–F) and efnb2a (G–I) in wild-type (A, D, G), han^s6 mutant (B, E, H) and hand2-overexpressing (C, F, I) embryos; lateral views, anterior to the left, at 24 hpf (A–C, G–I) and the 20 somite stage (D–F). (A–C) mrc1a expression in the posterior cardinal vein (blue arrow) was present in wild-type (A), absent in han^s6 mutant (B), and increased in hand2-overexpressing (C) embryos. Expression in the posterior blood island (red arrowhead) was grossly unaffected. (D–F) flt4 expression in the posterior cardinal vein (blue arrow) was present in wild-type (D), absent in han^s6 mutant (E), and increased in hand2-overexpressing (F) embryos. Expression in the dorsal aorta (red arrow) was grossly unaffected. (G–I) efnb2a expression in the dorsal aorta (red arrow) was present in wild-type (G), grossly unaffected in han^s6 mutant (H), and slightly increased in hand2-overexpressing (I) embryos. (J–O) Lateral views of three-dimensional reconstructions of Tg(flk1:ras-mcherry) expression in the vasculature of wild-type (J, M) and han^s6 mutant (K, N) embryos at 28 hpf (J, K) and 32 hpf (M, N). Pictured region in (J, K) is the area of the trunk boxed in the schematic (L); pictured region in (M, N) is the area of the tail boxed in the schematic (O). Both posterior cardinal vein (blue arrow) and dorsal aorta (red arrow) were present in wild-type (J) and han^s6 mutant (K) embryos. In contrast to wild-type (M), the caudal venous plexus (arrowhead) fails to undergo proper remodeling in han^s6 mutants (N). Scale bars represent 100 μm.