Figure 4.

Wnt signaling in the diastema. Dark field (A, B, and C) and light field (A’, B’, and C’) images of radioactive in situ hybridization on sagittal sections in wild-type mice at E14.5. Weak expression of Lrp4 (A and A’) and Lrp6 (B and B’) was observed in both upper diastema epithelium and mesenchyme. Upregulation of Lrp6 expression was detected in Lrp4^Hypo/Hypo mutants (C and C’). Supernumerary tooth in the diastema was found in Lrp4^Null/Null mutants at E18.5 (arrowhead in E). The first and the second molars were present in wild-type at E18.5 (D). Upregulation of ß-gal activity in the diastema was shown in Lrp4^Hypo/Hypo; BAT-gal mice at E14.5 (arrow in G) compared with β-gal activity in the diastema of wild-type at E14.5 (arrow in F). Both black and white arrows indicate rudimentary tooth bud.