Figure 2. Mouse molar tooth development from initiation to bell stages. Apoptotic cell distribution (black spots) and gene expression in the epithelial and mesenchymal cells of molecules mentioned in the review. No apoptosis is observed in the thickening of oral epithelim (white) prior to E12.5, when apoptosis is shown in the surface of the dental epithelium (A) and is extended to the tip of the growing tooth bud (B). At the cap stage (C), apoptosis is detected in the dental lamina and in the primary enamel knot. At the bell stage, apoptotic cells are found in the dental lamina, dental follicle, outer enamel epithelium, and secondary enamel knots (D). Few scattered apoptotic cells are also detectable in the dental mesenchyme (grey, italic).