The prenatal morphology of the articular disk of the human temporomandibular joint.

The prenatal morphology and ultrastructural of the articular disk of the human temporomandibular joint was studied to determine their relationship to the corresponding adult characteristics. The articular disks of seven human fetuses ranging in age from 10 to 32 weeks' gestation were examined. Our results show that the fetal articular disk has a genetically pre-determined appearance that substantially prefigures that of the adult. In profile, it was seen to be thin at the center and thick toward the periphery, like the adult structure; likewise, it was denser centrally than peripherally. Basically, it was found to be a fibrous structure: it was composed of a large number of connective tissue cells, while the blood vessels were limited to the periphery. A large number of elastic fibers was also observed. Posteriorly, they had a longitudinal orientation along the junction with the postglenoid tubercle of the temporal bone; along the periphery, they ran in an annular fashion.