Dynamic expression of Wnt ligands (Wnt3a, Wnt5a) and inhibitor (Dkk1) during morphogenesis of DM3. (A-I') In situ hybridization of Wnt3a, Wnt5a and Dkk1 during tooth germ morphogenesis; Boxed regions in C,F,I, were magnified in C',F',I'. (A-C,C') Wnt3a was mainly expressed in dental epithelium from E40-E60. (D-E) Wnt5a was expressed in primary enamel knot at E40, and expressed in both epithelium and dental papilla at E50. (F-F') At E60, Wnt5a was expressed both in IEE and odontoblasts. (G-H) Dkk1 was expressed in lower and peripheral regions of dental mesenchyme from E40 to E50 (red arrows). (I-I') At E60, Dkk1 was mainly expressed in lower regions of dental papilla (red arrow) and in pre-odontoblasts (yellow arrow). Scale bars represent 50μm (A,D,G), 100μm (B,C',E,F',H,I') and 200μm (C,F,I).