Fig. 4. Normal vasculature in BMPRIA NCC mutants. (A) No Wnt1-Cre expressing cells were observed in yolk sacs (corresponding embryo in A'). Expression of a Tie2-lacz transgene marking endothelial cells showed no structural defect in mutant yolk sacs (B) or in mutant embryos (D) compared with controls (C). (E-J) Immunostaining for the endothelial marker, PECAM1 (E,F; sagittal sections through descending aorta) and for smooth muscle actin (G,H; coronal sections through pharyngeal arch arteries, highlighted by arrowheads; and I,J, coronal sections through outflow tract tissue) further confirm the lack of structural defects in peripheral vessels of mutants. p, pharynx. All paired images are shown at identical magnification.