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

为了阐明骨基质纤维排列与应力或老化结构变化的关系，我们用扫描电镜对颌骨和关节盘的基质表面进行了观察。成熟食蟹猴下颌骨表面由胶原纤维束组成。在下颌骨，主要胶原纤维束沿下颌骨长轴平行排列。在下颌体凹凸不平的表面，束相互混杂。束沿肺泡边缘平行排列。然而，束在牙槽骨表面呈垂直排列。提示牙槽骨胶原纤维束的排列与咀嚼强度的方向有关。在下颌骨分支表面，束沿下颌骨分支长轴排列。大鼠胎鼠下颌髁纤维带细胞间基质较差。1周龄大鼠除髁突浅层纤维网外，其余原纤维排列有序，排列紧密。8周时，出现三维交织的原纤维束，原纤维网络不太突出。成熟大鼠和老年大鼠关节表面的纤维束在数量和宽度上增加，表明发育良好。未成熟大鼠的盘状表面被网状的胶原原纤维所占据。成熟大鼠和老年大鼠的纤维网络不像未成熟大鼠那样明显：在未成熟大鼠中，纤维束主要面向前后方向，平行于关节面，在关节面中主要存在，而纤维网络的排列比未成熟大鼠更粗略。这在外观上与在下颌髁表面看到的相似。

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.