Postnatal development of the human temporomandibular joint. I. A histological study.

Temporomandibular joints from 61 humans, aged 2 days to 27 years, were examined histologically. Four layers of the condyle were studied in detail. The outermost layer was richly vascularised in new-borns but by 3 years of age it had become avascular and contained few cells. In neonates the cartilage layer constituted a large part of the condyle but soon decreased in thickness and by 5-6 years of age it constituted only a thin zone of the top of the condyle. In the proliferative zone, mitoses occurred up to 13-15 years of age. This zone then decreased in thickness; the number of cells decreased, while the amount of intercellular substance increased. At birth, the temporal component was flat and was lined by vascularised connective tissue which became richer in collagen with increasing age. The cartilage layer was lacking in the fossa but was present on the tuberculum. A proliferative zone in this cartilage could be seen up to the age of 17-18 years and cartilage having only few cells was found in adults. Remodelling processes were seen in all components of the joints. The significance of the remodelling seen in the fossa and on the mandibular neck is discussed with relation to condylar and periosteal growth of the mandible.