Fig. 5.

Morphological transformation in Ednra^Hand2/+ ES cell-derived chimeric mice. (A) Representative surface appearance of E18.5 Ednra^Hand2/+ chimeric mice. Mutant mice demonstrate loss of vibrissae follicles, open eyelids (arrows), and polydactyly (arrowheads). (B–E) Craniofacial bone and cartilage elements of E18.5 Ednra^Neo/+ ES cell-derived (B) and Ednra^Hand2/+ ES cell-derived (C–E) chimeric mice. Whereas Ednra^Neo/+-chimeric mice show normal skeletal morphology (B), Ednra^Hand2/+-chimeric mice demonstrate transformation of the maxilla into dentary-like bone (C), which fuses to the premaxilla and contains an ectopic incisor at the tip (D). The condylar and angular processes of the dentary, gonial, ectotympanic, and squamosal bones were often malformed or absent (E). (F–I) Craniofacial skeletons of E15.5 wild-type (F and H) and Ednra^Hand2/+-chimeric (G and I) mice. Ectopic formation of MC-like, rod-shaped cartilage is present often with small and deformed ala temporalis in Ednra^Hand2/+-chimeric mice. The malleus, incus, stapes, and styloid process are deformed. agp, angular process; at, ala temporalis; cdp, condylar process; crp, coronoid process; dnt, dentary; etm, ectotympanic; fmx, frontal process of maxilla; gn, gonial; hy, hyoid; in, incus; jg, jugal; ma, malleus; mx, maxilla; pmx, premaxilla; sp, styloid process; sq, squamosal; st, stapes; UI, upper incisor; *, ectopic structure.