Expression of Wnt signalling pathway genes during tooth development

We have carried out comparative in situ hybridisation analysis of six Wnt g enes Wnts-3, -4, -5a, -6, -7b, and 10b together with Wnt receptor MFz6 and receptor agonist/antagonists MFrzb1 and Mfrp2 during murine odontogenesis f rom the earliest formation of the epithelial thickening to the early bell s tage. Expression of Wnt-4, Wnt-6, and one Wnt receptor MFz6 was observed in the facial, oral and dental epithelium. Wnt10b was localised specifically to the presumptive dental epithelium. Wnts-3 and -7b were expressed in oral epithelium but showed no expression in the presumptive dental epithelium. Wnt-3 also showed no expression in the epithelial cells of the molar bud st age tooth germs, but showed restricted expression in the enamel knots which are signalling centres believed to be involved in regulating tooth shape. Wnts-6, -10b and MFz6 were also detected in the primary and secondary ename l knots. Wnt-5a and agonist/antagonists MFrzb1 and Mfrp2 were expressed in a graded proximo-distal (P-D) manner in mesenchymal cells during the early stages of tooth development with no overlying expression in the oral or den tal epithelium. Wnt-5a and MFrzb1 show strong expression in the dental papi lla mesenchyme. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.