Fig. 8. Cx37^–/–Cx40^–/– E18.5 aortas do not show compensatory expression of Cx43 and exhibit normal expression of blood vessel cell markers. Sections of E18.5 aorta from wild-type (A,C,E) and Cx37^–/–Cx40^–/– (B,D,F) aorta were immunostained for Cx37, Cx40 and Cx43. (B,D) Cx37 and Cx40 were not detected in aortas with the Cx37^–/–Cx40^–/– genotype. (F) Cx37^–/–Cx40^–/– aortas did not show compensatory expression of Cx43 in endothelium. Cx37^–/–Cx40^–/– aortas exhibited normal expression of the endothelial marker, PECAM-1 (G,H) and smooth-muscle actin (SMA) (I,J). (K,L) Silver nitrate staining, which was performed to examine endothelial cell morphology and cell-cell contacts, was similar in Cx37^–/–Cx40^–/– (L) and wild-type (K) aorta. Bar, 50 µm for A-J, 20 µm for K,L.