Fig. 13.

Skeletal analysis of the Dlx2^+/−; Dlx5^−/− mutant through differential staining of bone (alizarin red) and cartilage (alcian blue). (A) Reference schema indicating the loss of one Dlx2 allele and two Dlx5 alleles in BA1. (B) Gross anatomy of wild-type (top) and the Dlx2^+/−; Dlx5^−/− neonates. (C) Norma lateralis view of a P0 wild-type skull. (D) Norma lateralis view of the Dlx2^+/−; Dlx5^−/− neonatal skull. The red and black arrowhead denotes the otic capsular deficiencies associated with the loss of Dlx5, while the green and black arrowhead highlights the nasal capsular defects. (E) Wild-type skulls highlighting, top to bottom, norma basalis view of a P0 skull minus the dentary, the middle ear with, and without, the dentary attached, and the palatal region minus the dentary of an E16.5 skull. (F) P0 and E16.5 skulls of Dlx2^+/−; Dlx5^−/− mutants. The black and green arrow points to the fusion of the incus and malleus, while the yellow arrowhead indicates the foramen in the retrotympanic process. The black and white arrow points to the edge of the transformed osseous body of Meckel's cartilage that articulates with the squamosal, while the orange arrowhead highlights the deficiency of the tegmen tympani. The transformed Meckel's cartilage is outlined in broken yellow lines; the endogenous ala temporalis is outlined in red. The black and blue arrowhead highlights the loss of normal dorsal squamosal architecture. (G) Dentary development in the Dlx2^+/−; Dlx5^−/− mutant. (H) Hyoid development in the Dlx2^+/−; Dlx5^−/− mutant. (I) Development of the middle ear and os paradoxicum in the Dlx2^+/−; Dlx5^−/− mutant, with a wild-type (left) and Dlx5^−/− mutant (right) structures for comparison. Note that the endogenous alisphenoid has been included with the Dlx2^+/−; Dlx5^−/− mutant. See text for further descriptions and list for abbreviations.