FIG. 7.
Expression of Hey2, ANF, and GATA4 in wild-type and Hey2 knockout hearts. Transverse sections show Hey2 expression in the compact layer of the ventricular myocardium (A and D), whereas ANF has a complementary expression pattern with strong expression in both atria and the trabecular layer of both ventricles of control hearts (B). (E) In Hey2 knockout hearts there is ectopic expression of ANF in the compact myocardium of the left ventricle (arrow). GATA4 expression is found ubiquitously in the myocardium of both wild-type and Hey2−/− (C and F). (G and H) Whole-mount in situ hybridization of wild-type (left) and Hey2−/− (right) hearts. Anterior (G) and posterior (H) views show ectopic ANF expression (arrowheads) in the compact compartment of the left ventricular wall. All hearts are derived from embryos at stage E17.5 except for (D), which is E12.5. a, atrium; v, ventricle; tra, trabecular layer; com, compact layer.