Figure 4.

The expression of Tfap2b during rodent tooth development. Radioactive in situ hybridization of Tfap2b expression on frontal (a–h) and sagittal (i, j) head sections. (a, b) At E12.5, Tfap2b is expressed in the entire molar tooth mesenchyme, whereas its expression is restricted to incisor mesenchymal cells facing tooth epithelium. (c, d) At bud stage E13.5 and (e, f) cap stage E14.5, Tfap2b expression is observed in molar mesenchyme, whereas its expression is restricted to a single-cell layer facing the oral cavity in the incisor epithelium. (g, h). Newborn. No expression of Tfap2b is found in the incisor tooth germ, whereas Tfap2b is expressed in the oral epithelium of the incisor region. In the molar tooth germ, Tfap2b shows restricted expression in caudal dental papillae facing the cervical loop. (i, j). At postnatal day 5, Tfap2b is expressed in caudal dental papillae and the dental follicle (arrows). Upper incisor (a, c, e, g) and molar (b, d, f, h, i, j) tooth germ epithelium is outlined in red dots.