Panel A. H&E staining of aortic valves from E16.5 Mib1K735R/+ (a), Mib1K735R/K735R (b), Mib1V943F/+ (c) and Mib1V943F/V943F mice (d) showing normal tricuspid morphology (asterisks). Panel B. Aortic valves and transverse heart sections of E16.5 Mib1+/+;Notch1KO/+ (e,f), Mib1K735R/+;Notch1+/− (g,h), Mib1+/+;Rbp+/− (i,j), and Mib1V943F/+;Rbp+/− (k,l) embryos. Bicuspid aortic valves are observed in the double heterozygotes (g,k). Note also the defective membranous ventricular septum, which is defective in Notch1KO/+;Mib1+/+ (e,f) and Mib1K735R/+;Notch1KO/+ hearts (g,h). Panel C. Percent of mice manifesting bicuspid aortic valve (BAV) and ventricular septal defect (VSD) phenotypes according to Mib1 variant and Notch1 and Rbp sensitization: Mib1K735R/+ (n=41), Mib1K735R/K735R (n=28), Mib1V943F/+ (n=50), Mib1V943F/V943F (n=24), Mib1+/+; Notch1+/− (n=11), Mib1K735R/+, Notch1+/− (n=9), Mib1+/+; Rbp+/− (n=10), and Mib1V943F/+;Rbp+/− (n=20).
Abbreviations: lv, left ventricle; rv, right ventricle. Scale bars, 100μm for aortic valve sections and 200μm for transverse heart sections.
**** P≤0.0001 by Chi-square.