Fig. 14.

Skeletal analysis of the [Dlx1^−/−; Dlx5^−/−], [Dlx1^−/−; Dlx5^+/−] and [Dlx1^+/−; Dlx5^−/−] mutants through differential staining of bone (alizarin red) and cartilage (alcian blue). (A) Norma lateralis view of a P0 wild-type skull. (B) Norma lateralis view of a Dlx1^−/−; Dlx5^−/− neonatal skull. (C) Norma lateralis view of a Dlx1^−/−; Dlx5^+/− neonatal skull. (D) Wild-type P0 skulls highlighting, left to right, the palatal region (norma basalis; yellow line outlining the palatine and green line outlining the pterygoid), the ala temporalis and lamina obturans components of the alisphenoid, norma lateralis view of the ear region with the primary and secondary jaw articulations, and the middle ear without the dentary attached. (E) P0 skulls of Dlx1^−/−; Dlx5^−/− mutants. The yellow arrowhead indicates the foramen in the retrotympanic process of the squamosal. The black and green arrow points to the fusion of the incus and malleus. The black and white arrow points to the edge of the transformed osseous body of Meckel's cartilage that articulates with the squamosal. The orange arrowhead highlights the loss of normal dorsal squamosal architecture, while the red and black arrow indicates the truncation of the zygomatic process of the squamosal, the black arrow highlights the diminished condylar process of the dentary. The two centres of ossification in the aberrant hyoid are indicated by the red and white arrowheads. A reference schema indicating the loss of two Dlx1 alleles and two Dlx5 alleles in BA1 is included. (F) P0 skulls of Dlx1^−/−; Dlx5^+/− mutants. The green arrowhead indicates the remnant of the distal tip of the ascending lamina that remains cartilaginous, a feature associated with the loss of Dlx1. A reference schema indicating the loss of two Dlx1 alleles and one Dlx5 allele in BA1 is included. (G) P0 skulls of Dlx1^+/−; Dlx5^−/− mutants. The black and green arrow indicates the dysmorphic ala temporalis and the red and black arrow indicates the transformation of the body of Meckel's cartilage, while the black arrow points to the dysmorphic condylar processes. The yellow and black arrow indicates the dysmorphology of the squamosal, and the black and blue arrow points to the dysmorphic angular process that is associated with the proximolingual aspect of the dentary. A reference schema indicating the loss of one Dlx1 allele and two Dlx5 alleles in BA1 is included. See text for further descriptions and list for abbreviations.