Väänänen H K, Hentunen T, Lakkakorpi P, Parvinen E K, Sundqvist K, Tuukkanen J
Department of Anatomy, University of Oulu, Finland.
Ann Chir Gynaecol. 1988;77(5-6):193-6.
The osteoclast is the main bone resorbing cell. It has several structural features which are related to its function. In active resorption stage this multinucleated giant cell shows remarkable polarity which, with its basolateral and apical membrane surfaces, resembles a secreting epithelial cell. The third specialized membrane area, sealing zone, mediates the attachment of the osteoclast to the bone surface. The rate of bone resorption can be regulated either by changing the number or the activity of resorbing osteoclasts. These processes can be influenced by different systemic circulating factors as well as local, bone matrix or other bone cell-derived factors. After activation of stem cells, preosteoclasts are guided to the bone surface where they undergo fusion into multinucleated osteoclasts. A special type of cell attachment to mineralized bone surface precedes actual resorption process. During cell attachment cytoskeletal structures are organized into a typical belt-like structure. The actual attachment receptor as well as its counterpart in bone matrix are not yet known. Bone mineral dissolution is then initiated by active secretion of H+ through the ruffled border membrane area. Acidification of the resorption lacuna together with hydrolytic enzymes completes finally the degradation of organic matrix of bone.
破骨细胞是主要的骨吸收细胞。它具有与其功能相关的几个结构特征。在活跃吸收阶段，这种多核巨细胞表现出显著的极性，其基底外侧和顶端膜表面类似于分泌上皮细胞。第三个特化膜区域，即封闭区，介导破骨细胞与骨表面的附着。骨吸收速率可以通过改变吸收性破骨细胞的数量或活性来调节。这些过程可受不同的全身循环因子以及局部、骨基质或其他骨细胞衍生因子的影响。干细胞激活后，前破骨细胞被引导至骨表面，在那里它们融合形成多核破骨细胞。在实际吸收过程之前，有一种特殊类型的细胞附着于矿化骨表面。在细胞附着过程中，细胞骨架结构组织成典型的带状结构。实际的附着受体及其在骨基质中的对应物尚不清楚。然后通过褶皱边缘膜区域主动分泌H+引发骨矿物质溶解。吸收腔的酸化与水解酶一起最终完成骨有机基质的降解。
