Deletion of Wls in embryonic mesenchyme causes craniofacial (white arrow, A), skeletal (white arrowhead,A) and midline defects (C). Weight and crown-rump length are diminished in Wlsf/f;Dermo1Cre/+ embryos (A). Malformed sternum and exposed heart (ectopia cordis) are reminiscent of Pentalogy of Cantrell (B). Extent of the lack of fusion of the sternum (dotted line, C) as determined by GFP fluorescence in the Wlsf/f;Dermo1Cre/+;Sox9EGFP mouse at E14.5 is shown (C). H&E staining depicts the anomalous shape of the rib cage after mesenchymal deletion of Wls in E13.5 embryos (D). The widest region of the rib cage is diminished in Wlsf/f;Dermo1Cre/+ embryos (D). Lu=Lung, L=Limb, N=4 ***p< 0.001