Figure 6  Signaling via ALK5 and ALK2 controls different aspects of aortico-pulmonary septation. Frontal sections from distal (top row) to proximal (bottom row) of the control (A-F), Alk5/Wnt1-Cre mutant (G-L) and Alk2/Wnt1-Cre mutant (M-R) samples (E11.5). A, C, E, G, I, K, M, O, Q, H&E staining; B, D, F, H, J, L, N, P, R, double staining for αSMA (brown) and β-galactosidase (green; R26R reporter assay). 6, the 6th PAA; AS, aortic sac; TA, truncus arteriosus; Ao, Aorta; PT, pulmonary trunk; Asterisks in A, B, M and N depict the AP septal mesenchyme.