<p><b>A,B</b>) In severely affected <i>RockDN;Wnt1-cre</i> embryos at E14.5, the frontonasal bones (stained with alcian blue) are absent (arrow in B, compare to A). Meckel's cartilage is also reduced in size (arrowhead in B, compare with A). <b>C,D</b>) Bone (red) and cartilage (blue) staining of a mildly affected <i>RockDN;Wnt1-cre</i> embryo at E18.5 (D), shows that the maxilla (arrowhead) and mandibular (arrow) bones are well formed, although the hyoid bone (red arrow) is reduced in size in mutant embryos. <b>E,F</b>) Inferior views of the base of the skull in mildly affected embryos shows that the basisphenoid and the presphenoid bones are hypoplastic in <i>RockDN;Wnt1-cre</i> embryos, whereas the nasal septum is completely missing. Moreover, the maxillary bones are widely separated in mutant embryos (double arrow in F), compared to control littermates (E). bs = basisphenoid; n = nasal septum; ps = presphenoid. Scale bar = 500 µm.</p
