Figure 3. Cultured mandibular primordia explants treated with protein beads. BSA control beads (A). OPG beads, 50 ng/mL (B); 100 ng/mL (C); 200 ng/mL (D), 400 ng/mL (E). Retardation of tooth epithelium invagination observed in explants treated with 200 ng/mL (D) and 400 ng/mL (E) of OPG protein. Tooth epithelium outlined in red. Scale bar: 90 µm.