Fig. 8. Coronary patterning is altered in Cx43-PCKO hearts. (A) One neonatal Cx43-PCKO heart has a right septal branch (RS) that originates from the left coronary artery. (B-E) Two separate coronary ostia are seen in the left coronary sinus of one of the Cx43-PCKO neonatal hearts (B,C). One ostium (LCO1) gives rise to a septal artery (B); the other (LCO2) gives rise to a large, aneurysmal artery that traverses the bulging tissue of the infundibulum (C,D). This mutant heart also has a blistering appearance of the right ventricular lateral wall, possibly consistent with subepicardial coronary plexuses described in the germline Cx43-null heart (arrows, E) (Walker et al., 2005). (F-H) Another neonatal Cx43-PCKO heart has dual right coronary ostia. One ostium (RCO1) leads to a large septal artery (F). The second right coronary ostium (RCO2) gives rise to a septal branch and a myocardial tributary (G), which subsequently divides into branches that cross through the RV infundibulum (arrows, H). (I-K) Tunneling of the right coronary artery (arrows) through the wall of the aorta is shown in an E17.5 Cx43-PCKO heart. (L) Two out of five neonatal heterozygous Cx43-null (Cx43^fo/wt) hearts demonstrated coronary artery branching at the ostium. Ao, aorta; LC, left coronary artery; LCO, left coronary ostium; LM, left myocardial branch; LS, left septal branch; LV, left ventricle; M, myocardial branch; PA, pulmonary artery; RA, right atrium; RC, right coronary artery; RCO, right coronary ostium; RV, right ventricle; S, septal branch. Scale bar: 225 µm for A-D; 112.5 µm for E,G-L; 56 µm for F.