Ultrastructural and histochemical studies on the coupling phenomena between bone formation and bone resorption

本研究的基本目的是阐明骨吸收和骨形成之间耦合现象的精细结构和细胞化学特征。第一个目标是阐明破骨细胞性骨吸收和随后的成骨细胞性骨形成之间的细胞化学事件。ACPase阳性的吸收骨面延续至骨水泥线，在其上诱导成骨细胞形成新骨。提示破骨细胞可能以骨吸收的形式移动，形成一条骨水泥线，这可能是骨吸收与骨形成耦合的原因之一。第二个目标是揭示破骨细胞和成骨细胞在破骨细胞分化和激活过程中关系的精细结构和细胞化学细节。首先，在器官培养上用降钙素(CT)进行光镜和EM放射自显影(A.R)以鉴定破骨细胞。显影银粒[125；>I]-C…TRACP阳性的单核细胞和多核细胞上的T细胞较多。在EM-A.R中，成骨细胞前体和破骨细胞的高尔基体和质膜上均可见银颗粒，提示[CT]-CT与破骨细胞的胞浆受体结合，然后内化并向Goligi小体延伸。然后进行超微结构和凝集素细胞化学观察。成骨细胞与正在分化的破骨细胞密切接触，破骨细胞与成骨细胞面对面可见灶性连接和包被凹陷。小鼠脾细胞与新鲜分离的成骨细胞在1，25-(OH)_2D_3存在下共培养，形成TRACF阳性的多核细胞。在这种情况下，成骨细胞也以与体内相同的方式与脾细胞密切接触。这些结果表明，破骨细胞前体细胞通过细胞-细胞直接接触的方式分化为破骨细胞需要成骨细胞，这种密切的细胞接触可能使破骨细胞前体细胞对成骨细胞表面存在的刺激产生反应。在发育中的破骨细胞和邻近的成骨细胞的质膜上均观察到凝集素反应，提示质膜上的糖残基可能通过受体在细胞识别中发挥作用，也可能参与多种局部因子的聚集。较少

The basic objection of this study is to elucidate the fine structural and cytochemical characteristics of the coupling phenomena between bone resorption and formation. The first objective was designed to elucidate The cyto chemical events between the osteoclastic bone resorption and subsequent osteoblastic bone formation. The ACPase positive resorbed bone surface continued to the cement line, on which osteoblasts were induced and formed a new bone. This suggests that the osyteoclasts may move as a resorbing bone and form a cement line, which may be a responsible for the coupling of the bone resorption and formation. The second objective was to reveal fine structural and cytochemical details on relationships between osteoclastic and osteoblastic cells in the differentiation and activation processes of osteoclasts. At first, LM and EM autoradiography(A.R) was performed on an organ culture using [^<125>I] calcitonin(CT) to identify osteoclastic cells.Developed silver grains of [^<125>I]-C … More T were located on the TRACP-positive mono and multinucleated cells. In the EM-A.R, silver grains could be observed on the Golgi bodies and plasma membranes of both osteoblast progenitors and osteoclasts, suggesting that[^<125>I]-CT binds to receptors of plasma memoranes of osteoclastic cells, then internalized and turned to reach to the Goligi bodies. Ultrastructural and lectin-cytochemical observations were then carried out. Osteoblastic cells had close contact with differentiating osteoclasts, where focal connections and coated pits could frequently be observed in both osteoclastic and osteoblastic cells facing each other.When mouse spleen cells were co-cultured with freshly isolated osteoblasts in the presence of 1,25-(OH)_2D_3, TRACF-positive multinuclear cells were formed. In this case, osteoblasts had also close contact with spleen cells in the same way as shown in vivo. These results indicate that osteoblastic cells are required for the differentiation of osteoclast orogenitors into osteoclasts by way of direct cell-cell contact, and this intimate cell contact presumably enables the osteoclast progenitors to respond to stimuli present on the osteoblastic cell surface. Lectin reaction was seen on Plasma membranes both in developing osteoclastic and adjacent osteoblastic cells suggesting that sugar residues on the plasma membrane may play a role in the cellular recognition via receptors, and also may be involved in concentrating appropriate amount of several local factors. Less