Internal organ situs and morphology was normal in Foxh1mEH1/mEH1 embryos. (A,B) Normal dextral looping of the heart was observed in E10.5 Foxh1mEH1/mEH1 embryos. (C,D) Different colors of liquid latex were injected into the right (yellow) and left (blue) ventricles of E15.5 control and Foxh1mEH1/mEH1 embryos to highlight potential defects in ventricular septation, formation and positioning of the great arteries and aortic arch. No latex mixing, which would have indicated septation defects, was observed in Foxh1mEH1/mEH1 embryos. Also, the pulmonary trunk (yellow arrowhead) always appeared ventral to the aorta (blue arrowhead), and aortic branching was equivalent to control embryos. (E–H) Overall organ placement and morphology was unaffected in Foxh1mEH1/mEH1 embryos at E15.5. Embryo orientations: (A–E, G) Ventral views. (F, H) Dorsal views. Scale bars: (A,B) 500 μm; (C–H) 1 mm. H, heart; I, intestine; K, kidney; L, left; Li, liver; Lu, lung; LV; left ventricle; OT, outflow tract; RV, right ventricle; St, stomach; T, thymus.