Temporomandibular joint development in the marmoset--a mirror of man

The timing of temporomandibular joint (TMJ) development in the cotton-eared marmoset was studied by histological examination of joints taken during embryogenesis and compared with TMJ development reported in man. Specimens were obtained via hysterotomy at intervals during pregnancies dated by estimation of uterine size or fetal head diameter. Elements of the marmoset TMJ were first identified at 70-85 days gestation, and TMJ morphogenesis was complete at 110-125 days. The chronological events of TMJ embryogenesis were found to run parallel to the human but were delayed by 30 days. At birth, after 150 days gestation, the marmoset TMJ resembled the human joint at the end of the second trimester, with all cell layers of the condylar cartilage in place and ossification started in temporal and condylar components. A new world primate, the cotton-eared marmoset is proposed as an animal model for craniofacial studies involving the TMJ on grounds of its close comparability to man.