Fig. 6. Heart hypertrophy and semilunar valve defects in hEGFR^KI/KI mice. (A) Appearance of control and hEGFR^KI/KI hearts at 3 weeks of age. (B) Heart weights and relative heart weights corrected for body weight of control and hEGFR^KI/KI mice. Data represent the mean±s.d. of five 3-month-old mice and hearts. Cross-sections through the heart of control (C,F), hEGFR^KI/KI (D,G) and Egfr^-/- (E) mice at different postnatal stages, showing severe myocardial hypertrophy in hEGFR^KI/KI mice. lv, left ventricle; se, septum; rv, right ventricle. Histological sections of semilunar valves from control (H) and hEGFR^KI/KI (I) hearts. The arrows in H and I indicate the aortic valve leaflets, which are thickened and hypercellular in hEGFR^KI/KI hearts. w, weeks; m, months. All sections are stained with Haematoxylin and Eosin.