Developmental differences in the ossification process of the human corpus and ramus mandibulae.

A correlation was sought between the organization of the dental crest and the ossification of the corpus mandibulae in 14 human embryos and 13 human fetuses. The different types of ossification between the corpus and the ramus mandibulae suggest that the cartilago mandibularis (meckeliensis) guides the formation of the mandibula, while the dental crest acts as a coorganizer. In the area of the foramen mentale, the lamina dentalis begins to invaginate (to give rise to the dental crest), and at this level intramembranous ossification of the corpus mandibulae commences. These findings, together with the presence of the cartilago mandibularis before the appearance of the dental crest, and the fact that the former is seen along the entire length of the mandibula (from the symphysis mandibulae to the capsula otica), support the hypothesis that the dental crest, rather than the cartilago mandibularis, acts as the coorganizer in the corpus mandibulae.