Fig. 16.

Skeletal analysis of compound Dlx1; Dlx2; Dlx5 mutants. (A) Wild-type P0 skulls highlighting, left to right, the palatal region (norma basalis), the ala temporalis and lamina obturans components of the alisphenoid, and the primary and secondary jaw articulations, and the middle ear with the dentary associated. (B) P0 and E16.5 skulls of Dlx1/2^−/−; Dlx5^−/− mutants and a reference schema indicating the loss of two Dlx1 alleles, two Dlx2 alleles and two Dlx5 alleles. The orange arrowhead points to the cartilaginous strut that extends from the basisphenoid toward the rostral otic capsule, while the black and yellow arrowhead indicates the associated parallel dermal ossification. The red and blue arrowhead points to the extensive fusion of the remnant of the pars canalicularis of the otic capsule to the taenia marginalis and parietal plate. The black and green arrow indicates the extensive foramen (infraorbital?) that develops in a lateral process (black and purple arrow) emanating from the caudal end of the incisive canal. The orange and black arrow points to the lingual aspect of the truncated dentary. Note the absence of a molar alveolus. The blue and black arrow highlights a cartilaginous nodule often associated with the proximal end of the dentary. The black and white arrowhead brings attention to the nature of the palate: while still cleft, the palatal development progresses further than in the Dlx1/2^−/− single mutants. (C) P0 and skulls of Dlx1/2^−/−; Dlx5^+/− mutants. A reference schema indicating the loss of two Dlx1 alleles, two Dlx2 alleles and one Dlx5 allele is included. The blue arrow indicates the exacerbated deficiency in proximal dentary development exhibited by the Dlx1/2^−/−; Dlx5^+/− mutants relative to the Dlx2^−/−; Dlx5^+/− mutants. The red and white arrow indicates the disruption of Meckel's cartilage, while the green and black arrowhead points to the loss of the superior cornu of the thyroid cartilage. (D) P0 skulls of Dlx1/2^+/−; Dlx5^−/− mutants. A reference schema indicating the loss of one Dlx1 allele, one Dlx2 allele and two Dlx5 alleles is included. 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, and the black and white arrow points to the edge of the transformed osseous body of Meckel's cartilage that articulates with the squamosal. The black and turquoise arrowhead indicates the expanded, un-ossified lamina formed from the medial projection of the transformed body of Meckel's cartilage. The black arrow points to the deficiencies of the dentary. See text for further descriptions and list for abbreviations.