Effect of Mechanical Forces on Chondrocyte Maturation and Differentiation in the Mandibular Condyle of the Rat

Abstract

The effects of mechanical factors on the growth of the mandibular condyle were studied by monitoring the maturation of the mesenchymal cells in 55 rats. Thirty-five animals were fed normal pellet food, and 20 were fed a soft diet and their incisors were cut regularly. 3H-thymidine was injected intraperitoneally three days before death at 18, 23, or 33 days. Histologic sections showed the most advanced 3H-thymidine-labeled cells to occur deep in the cartilage, in the lower hypertrophic cell layer in anterior and posterior regions of the condyle, and in the upper hypertrophic cell layer in the superior region at the age of 18 days. A distinct difference in the maturation state of the labeled cells could also be observed between these regions. In animals fed a soft diet, maturation was slower in the superior region of the condyle and faster in the posterior region than in the normal rats. The rate at which cells stepped out of the proliferating cell pool was measured by use of monoclonal antibodies against proliferating cell nuclear antigen. The ratio between labeled cells in the proliferating cell layer and the number of labeled cells beneath it was greater in control animals than in the soft-diet animals. The rate of differentiation and maturation of mesenchymal cells into chondrocytes seems to be controlled by mechanical factors.

Functional Lateral Shift of the Mandible Effects on the Expression of ECM in Rat Temporomandibular Cartilage

“…After matrix mineralization, this part of the cartilage is replaced by bone via erosion. 23 Thus, it is conceivable that rates of chondrocyte proliferation and erosion may affect the presence of these ECMs. Study of cell dynamics, with the same model used by Sato et al, 12 also supported this view.…”

Compressive force promotes chondrogenic differentiation and hypertrophy in midpalatal suture cartilage in growing rats

“…Many studies have demonstrated the biomechanical properties of secondary cartilage in response to various mechanical forces (Hall, 1972(Hall, , 1979McNamara and Carlson, 1979;Kantomaa, 1982;Copray et al, 1985Copray et al, , 1986Hinton, 1988;Kantomaa and Hall, 1988;Luder et al, 1988;Takahashi, 1991;Kantomaa et al, 1994;Takahashi et al, 1995Takahashi et al, , 1996a, and many investigators have reported the effects of compressive force on the proliferation of cells and collagen and proteoglycan synthesis in mandibular condylar cartilage (DeWitt et al, 1984;Copray et al, 1985;Kantomaa et al, 1994). Only our previous study, however, reports the phenotypic changes in these cells under compressive force (Saitoh et al, 1997).…”

Temporomandibular joint formation and condyle growth require Indian hedgehog signaling

“…The so-structured condyle exhibits fairly rapid growth and elongation toward the differentiating temporal bone. Of interest, this elongation process is largely due to appositional growth at its apical end in which chondroprogenitor cells in the polymorphic cell layer undergo chondrogenesis and the newly differentiated chondrocytes become incorporated into the underlying condylar cartilaginous tissue (Kantomaa et al, 1994). Hence, condyle elongation is quite different from that occurring in other developing skeletal elements such as long bones or ribs in which elongation is contributed by mitotic activity of chondrocytes within the proliferative zone of the growth plate.…”