On the importance of cAMP and Ca++ in mandibular condylar growth and adaptation

The origin of the mandibular condylar cartilage is not periosteal, like that of the other secondary cartilages; this cartilage originates in a cellular blastema of its own. Despite the fact that the development of secondary cartilages, in general, is dependent on mechanical irritation, that of the condylar cartilage is not. The low level of function experienced postnatally seems to favor growth, but because the proliferation cells of the condylar cartilage are multipotential, they switch their differentiation pathway in the direction of osteoblasts in the absence of function, and growth of the cartilage ceases. This regulation of differentiation is mediated by maturation of the cartilage cells. If function is not present, maturation advances rapidly, and the mature cartilage induces bone formation instead of cartilage. Cyclic AMP and Ca are important mediators in this process, because they affect the advancement of maturation.