Immunohistochemistry for Matrix Proteins in newly formed Mandibular Condylar Cartilage in a Human Fetus

A newly formed mandibular condylar cartilage at 9 weeks of gestation (37mm crown rump length) was analyzed immunohistochemically. The cells in newly formed cartilage and condensed mesenchymal cells posterior to the cartilage showed alkaline phosphatase immunoreactivity, confirming the mandibular condylar cartilage in human is also derived from periosteum-like tissue, as demonstrated in rodents. The newly formed condylar cartilage simultaneously expresses immunoreactivity for collagen types I and II, aggrecan, versican, and tenascin-C as well as hyaluronan staining but not for collagen type X. Thus newly-formed condylar cartilage has fibrocartilaginous characteristics, but the characteristic that rapidly differentiated into hypertrophic chondrocytes, which is recognized in rodent secondary cartilage, is not conspicuous in human.