Fig. 1.

Comparison of Tbx5 cognate genes in vertebrates. Skate Tbx5 (A) and Flt4 (B) expression at stage 23. Zebrafish tbx5a (C) and flt4 (D) expression at 22 hpf. Sea lamprey Tbx4/5 (E) and Flt1/4 (F) expression at stage 24. (G) A depiction of the Tbx5 expression domain (purple) relative to embryonic components in jawed and jawless vertebrates. acv, anterior cardinal vein; ccv, common cardinal vein; e, eye; g, gills; h, heart; hv, hepatocardiac vein; pcv, posterior cardinal vein; 9, somite 9. (Scale bars: 200 μm.)