Fig. 1. Myocardium-specific inactivation of Tgfbr2. (A,B) Whole-mount (A) and sectional (B) examination of a cTnTcre;Tgfbr2^loxp/loxp;R26R embryo at E10.5 stained with X-gal. (C,D) PCR analysis of DNA isolated from either the myocardium (M) or endocardium (E) of the AVC region of an E10.0 cTnTcre;Tgfbr2^loxp/loxp;R26R embryonic heart. (C) Primers p1 and p2 detected the unrecombined Tgfbr2^loxp allele, whereas primers p1 and p3 detected the recombined allele (Bhowmick et al., 2004). (D) The recombined allele can be detected only from myocardial cells (lane 1) and not endocardial cells (lane 2), whereas the unrecombined allele is hardly detected from myocardial cells (lane 3 versus 4). The lacZ primers were used as a control to show that a similar amount of DNA template was used for the myocardium (lane 5) and endocardium (lane 6) in the PCR analysis. (E-H) Frontal sections of a wild-type (E) and a cTnTcre;Tgfbr2^loxp/loxp (F-H) embryonic heart. The arrow in F indicates the VSD. Both the aorta and pulmonary trunk are connected to the right ventricle (G,H), resulting in a DORV defect. A, atrium; ao, aorta; cko, cTnTcre;Tgfbr2^loxp/loxp; ctrl, wild-type embryos; E, endocardial cells; H, heart; LA, left atrium; LV, left ventricle; M, myocardial cells; oft, outflow tract; pt, pulmonary trunk; RA, right atrium; RV, right ventricle; V, ventricle.