Figure 3.

Craniofacial, axial, and appendicular skeletal defects of Dlx5/6^−/− embryos. (A) Whole-mount Alcian blue (AB) staining reveals the absence of Meckel's, nasal prominence and central digit cartilages of E14.5 mutant embryos. (B) Alcian blue and alizarin red (AB/AR) staining shows the absence of calvaria, maxillary, and mandibular bones of E16.5 mutant embryos. In addition, the axial skeleton, including vertebral bodies (inset), has little or no ossification and the ribs are malformed. The forelimbs (left columns) also have a delay in ossification (bracketed region), or a complete absence of ossification (star) and hindlimb digits (right columns) are absent and/or fused. (C) The delay in ossification becomes less severe in the axial and appendicular skeleton by E18.5. However, the ribs remain disfigured and the ratio of forelimb ossification to cartilage remains retarded. Hindlimbs and forelimbs (inset) have clefting due to missing and fused digits. Abbreviations: C, calvaria; FN, frontonasal cartilage; MC, Meckel's cartilage; Md; Mandible.