Marks S C, Cahill D R
Am J Anat. 1986 Nov;177(3):427-38. doi: 10.1002/aja.1001770311.
Previous work from our laboratories has established that eruption of the permanent mandibular premolars in dogs is dependent upon the presence of the dental follicle and that it involves resorption of alveolar bone and the roots of the deciduous predecessor above and formation of alveolar bone below the developing crown. This study illustrates the topography of the bone surfaces of the crypt by scanning electron microscopy and the ultrastructure of the cells on alveolar bone surfaces during tooth eruption. Above the developing crown where the eruption pathway forms, the bone surface is a pitted sheet, the characteristic topographic feature of bone resorption; between the crown and the mandibular canal, the bone surface has numerous interconnecting trabeculae. Transmission electron microscopy of bone cells lining the eruption pathway area of the crypt showed numerous osteoclasts with adjacent mononuclear cells. Both cell types contained specific, membrane-bound cytoplasmic vesicles shown by the work of others to be characteristic features of osteoclasts and their precursors. Basal trabeculated bone in the crypt was covered by plump osteoblasts. These data show that the metabolic events in alveolar bone associated with tooth eruption have the appropriate cellular and bony surface correlates and that the suspected control of alveolar bone resorption by the dental follicle may be mediated by its recruiting and directing to adjacent bone surfaces the mononuclear precursors of osteoclasts.
我们实验室之前的研究已经证实，犬类下颌恒牙前磨牙的萌出依赖于牙囊的存在，且这一过程涉及牙槽骨以及上方乳牙牙根的吸收，同时还包括在发育中牙冠下方形成牙槽骨。本研究通过扫描电子显微镜展示了牙囊骨表面的形态以及牙齿萌出过程中牙槽骨表面细胞的超微结构。在发育中牙冠上方即将形成萌出道的区域，骨表面呈凹坑状薄片，这是骨吸收的典型形态特征；在牙冠与下颌管之间，骨表面有许多相互连接的小梁。对牙囊萌出道区域内衬骨细胞进行透射电子显微镜观察，发现有大量破骨细胞以及相邻的单核细胞。这两种细胞类型均含有特定的、膜结合的细胞质囊泡，其他研究表明这是破骨细胞及其前体细胞的特征性结构。牙囊内底部有小梁的骨组织被丰满的成骨细胞覆盖。这些数据表明，与牙齿萌出相关的牙槽骨代谢事件具有相应的细胞和骨表面特征，并且牙囊对牙槽骨吸收的疑似调控作用可能是通过招募破骨细胞的单核前体细胞并将其引导至相邻骨表面来实现的。
