Fig. 7. AV myocardium defect in the Bmp2 CKO mutants at 9.5 dpc. In wild-type embryos, chamber-specific genes, including Anf (A,C), chisel (E,G) and connexin 40 (I,K), are expressed in the myocardium of the atrium and ventricle but not in the AV myocardium (denoted by arrows). In the Bmp2 CKO mutant, the expression of Anf (B,D), chisel (F,H) and connexin 40 (J,L) is expanded into the AV canal myocardium (denoted by arrows). Tgfß2 is expressed in the AV myocardium in wild-type embryos (M) but is significantly reduced in the mutant, as indicated by arrows (N). Lef1 is also expressed in the AV myocardium in wild-type embryos (O) but is significantly reduced in the mutant (P, indicated by arrow). a, atrium; v, ventricle.