Three-dimensional ultrastructural study on fibril arrangement of jawbone matrix and articular disk

点击翻译按钮获取中文摘要

On the purpose to clarify the relationship between fibril arrangement of bone matrix and stress or structural changes of aging, we examined the matrix surface of jaw bones and the articular disks with scanning electron microscope.The surface of mandibles of mature crab-eating monkeys was composed of collagen fibril bundles. At the mandibular body, main collagen finbril bundles were running in parallel along the long axis of mandibular body. At the uneven surface of mandibular body, bundles mingled each other. Bundles were running in parallel along the alveolar border. However, bundles were running perpen-dicularly at the surface of alveolar bone. It was suggested that the arrangement of collagen fibril bundles of alveolar bone was related to the direction of the masticatory strength. At the surface of ramus of mandible, bundles were running along the long axis of ramus of mandible.The fibrous zone of the mandibular condyle from rat fetuses was poor in intercellular matrix. In 1-week-old rats, the fibrils were orderly rearranged and closely packed except fibrillar network in the superficial layr of the condyle. At 8 weeks, three dimensionally interwoven bundles of fibrils were present and the fibrillar network was less prominent. In mature and senile rats, the fibrillar bundles of the articular surface increased in number and width indicative of a well-development.The disk surfaces of immature rats were occupied by collagen fibrils interwoven in the form of network. The fibril network in matured and aged rats was not a conspicuous as in immature rat : in those rats, fibril bundles oriented principally in an anteroposterior direction and parallel to the articular surfaces were predominantly present in the surfaces, while the fibril network was arranged more roughly than in immature rats. This is similar in appearance to that seen on the mandibular condylar surface.