Figure 1

Histology and stage of the developing miniature pig mandibular deciduous molar. (A) Normal mandibular deciduous molar with 5 or 6 main cusps and 5 roots. (B) Developmental stages of the mandibular deciduous molar in the miniature pig. The relatively typical points in time are E35 (bud stage), E45 (cap stage), E50 (early bell stage), and E60 (late bell stage). (C, G) The epithelium grew into the mesenchyme to form the dental lamina (dl) at E30. (D, H) The dental lamina formed the dental bud (db) at E35. (E, I) The peripheral cells of the enamel organ extended outside at E40. (F, J) A typical cap stage appeared at E45, with differentiation of the outer enamel epithelial cells (oe), inner enamel epithelial cells (ie), and stellate reticular cells (s). The dental papilla (p) could also be observed. (K, O) At E50, the typical early bell stage was observed. The cusp morphology could be seen at the junction of the inner enamel epithelium and dental papilla. The stratum intermedium (si) appeared between the inner enamel epithelium and the stellate reticulum. (L, P) Morphological findings at E55. (M, Q) By E60, the molar reached late bell stage. In the cusp region, dental epithelial cells and mesenchymal cells were polarized and cells lengthened to become pre-ameloblast and pre-odontoblast. (N, R) Continuous and intact ameloblasts (ab), enamel (e), dentin (d), and odontoblasts (ob) were observed in the molar cusp at E65. Scale bars: 5 mm in A, 50 μm in C-F and O-R, 20 μm in G-J, and 100 μm in K-N.