FIG. 5.

Histological analysis of hematoxylin-and-eosin-stained longitudinal sections through hearts from wild-type (WT), mRor1^−/−, and mRor2^−/− newborns and a double mutant embryo (E19.5). The hearts of mRor1^−/− newborns exhibit no apparent abnormalities. Asterisks indicate cardiac VSD in the mRor2^−/− newborn and the mRor1^−/−; mRor2^−/− embryo (D) and the complete transposition of the great arteries in the mRor1^−/−; mRor2^−/− embryo (E). The complete transposition of the great arteries with a situs solitus was observed and was characterized by a discordant arterial connection, while the atrioventricular connection was concordant (E) (3, 6). Serial sections revealed that the pulmonary artery (PA) arising from the left ventricle (LV) ran into the lung directly and that the aorta (Ao) ran out from the right ventricle (RV) in the double mutant embryo (data not shown). The spleen was found on the left side of the abdominal cavity of the double mutant embryo, and neither situs inversus nor asplenia was observed (data not shown). Bar, 300 μm.