Figure 3. Cell proliferation is reduced in Runx2 mutant teeth, and their mesenchyme responnds to Shh signal. (A) Runx2 mutant dental mesenchyme is able to respond to Shh signal. (a–d) Upper molar dental mesenchyme. (e–l) Lower molar dental mesenchyme. Shh-soaked beads induced in Runx2 mutant dental mesenchyme intense expression of Ptc1 (b,f) and Gli1 (d,h), which were comparable with the wild-types (a,e,c,g). There was no signal around the BSA control beads (i–l). (B) Cell proliferation is reduced in Runx2 mutant molars. Proliferating cells incorporating BrdU are stained in brown. (a) E14 wild-type molars (percent proliferating cells: [upper molar] epithelium 58%, mesenchyme 86%; [lower molar] epithelium 61%, mesenchyme 85%), (b) E14 Runx2 mutant molars (upper molar, epithelium 33%, mesenchyme 53%; lower molar, epithelium 19%, mesenchyme 36%). Scale bar: 200 µm.