Fig. 5. Defective endocardium in Bmp2 CKO mutant embryos. Immunohistochemistry of NFATc1 in wild-type (A) and Bmp2 CKO mutant (B) embryos at 8.5 dpc. At 9.5 dpc, there is upregulation of NFATc1 expression in the AV cushion endocardium (C) in wild-type embryos but in the Bmp2 mutant many of the endocardial cells are negative and there is no regional specificity of the signal (D). Arrows denote positively stained cells. Whole-mount in-situ hybridization followed by sectioning for some probes with Twist1 (E-H), Msx1 (I-L), Smad6 (M,N), VE-cadherin (O,P), Notch1 (Q-T) and Snai1 (U,V) probes at 9.5 dpc in wild-type and Bmp2 CKO mutant embryos. Arrows denote positive hybridization signal or areas where signal is up- or downregulated in the mutant embryo. Probes and genotypes are labeled. a, atrium; ba1, first branchial arch; v, ventricle.