Early stages of tooth morphogenesis in mouse analyzed by 3D reconstructions.

Computer-aided 3D reconstructions were used to investigate early odontogenesis in the ICR mouse, from the dental lamina to the cap stage. The diastemal region of the maxilla was not an empty zone: five transient epithelial rudiments (D1-D5) were found between ED 12.5-13.5. Two further rudiments (R1 and R2) were observed between D5 and the maxillary first molar primordium, whose bud emerged at ED 13.5. These rudiments might be related to vestiges of ancestral teeth. During this period, only an epithelial lamina was observed in front of the bud-shaped molar epithelium in the cheek region of the mandible. Apoptosis plays an important role in the reduction of antemolar rudiments in the maxilla and in the remodeling of the epithelium anterior to the M1 bud and cap in both jaws: two successive waves of apoptosis were detected in the mandible and in the maxilla. Computer-aided 3D reconstructions clearly demonstrated that morphologically different developmental stages coexist along the anteroposterior axis of M1 in both jaws.