Fig. 3. Congenital heart defects in Pds5B^-/- mice mimic those observed in CdLS patients. (A,B) Sections of wild-type mouse hearts demonstrating (A) the intact ventricular septum and relationships of the aortic, tricuspid and mitral valves, and (B) an intact atrial septum. (C-F) Sections of mutant mouse hearts showing: (C) a large perimembranous VSD with the aorta riding over both ventricles; (D) a secundum ASD; (E) a muscular VSD; (F) a common atrioventricular canal defect. Note the single atrioventricular valve and the common defect of the atrial and ventricular septum. Arrows indicate the respective defects. AoV, TV, MV, aortic, tricuspid and mitral valve; RA, LA, right, left atrium; RV, LV, right, left ventricle. Scale bar: 1 mm. (G) Summary of congenital heart defects in Pds5B^-/- mice. P<0.001 is calculated by a Z-test for significant differences in total incidence between WT and Pds5B homozygotes.