Fig. 5. Defects in vessel remodeling and the heart of the Smad4 CKO embryos. (A) E9.5 and E10.5 yolk sacs of Smad4 CKO were subjected to whole-mount staining with anti-PECAM1 (CD31) antibody. The controls (wild type) showed complex branching (left), but Smad4 CKO embryos displayed only the primary vascular plexus (right). Scale bars: 500 µm. (B) Expression of Id genes in the Smad4 CKO yolk sacs. RNAs from two wild-type and three Smad4 CKO embryos were used for qRT-PCR. ^*P<0.05. (C-D') Hematoxylin and Eosin staining of E9.5 heart of Smad4 CKO embryos. (C'-D'') Higher magnification of the insets (green and black) in C and D, respectively. Arrows indicate the cushion in the AVC and arrowheads indicate the trabeculae in the ventricle. Scale bars: 200 µm.