Li Hua, Zhang Xian, Wang Fan, Li Ruixiang, Wang Song
Department of Anatomy, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, China.
Sichuan Da Xue Xue Bao Yi Xue Ban. 2003 Apr;34(2):274-6.
To understand the regulation of chondrocyte proliferation in callus.
The histological structure of callus was observed and the percent of positive cells of Cylin D3, Cyclin E, Cyclin A, PCNA and BrdU in callus of 20 male SD rats were caculated in the fracture healing model by HE staining and immunohistochemical staining at 1, 2, 3 and 4 weeks after fracture.
The callus under light microscope could be divided into four zones: resting zone(RZ), proliferating zone(PZ), mature zone(MZ) and hypertrophic zone(HZ). The arrangement of chondrocytes in callus was irregular and the boundary between the neighboring zones not as clear as on growth plate. The findings indicated that the proliferation and differentiation of the cells in cambium layer of periosteum and RZ played an important role during fracture healing in the first week; the proliferation of chondrocytes in PZ was very active in the second week, meanwhile the cells in cambium layer became quiet; the proliferating activity of chondrocytes in all these zones became declining and the chondrocytes came to be mature and hypertrophic gradually in the fourth week.
The proliferating cells in the early stage of fracture healing should have supplied enough chondrocytes, after that time these cells would no longer proliferate; the skeletal repair would be carried out and be accompanied with the proceeding proliferation and differentiation of chondrocytes. After all, the proliferation of chondrocytes in callus is closely related to skeletal repair. Additional characters and elucidation of fracture healing will lay the foundation of subsequent studies aimed at identifying mechanisms for skeletal repair.
了解骨痂中软骨细胞增殖的调控情况。
在骨折愈合模型中，对20只雄性SD大鼠骨折后1、2、3和4周的骨痂进行组织学结构观察，并通过HE染色和免疫组织化学染色计算骨痂中细胞周期蛋白D3、细胞周期蛋白E、细胞周期蛋白A、增殖细胞核抗原（PCNA）和5-溴脱氧尿嘧啶核苷（BrdU）阳性细胞的百分比。
光镜下骨痂可分为四个区域：静止区（RZ）、增殖区（PZ）、成熟区（MZ）和肥大区（HZ）。骨痂中软骨细胞排列不规则，相邻区域之间的边界不如生长板处清晰。结果表明，骨折后第一周，骨膜形成层和静止区细胞的增殖和分化在骨折愈合过程中起重要作用；第二周，增殖区软骨细胞增殖非常活跃，同时形成层细胞变得静止；第四周，所有这些区域软骨细胞的增殖活性下降，软骨细胞逐渐成熟和肥大。
骨折愈合早期的增殖细胞应已提供足够的软骨细胞，此后这些细胞不再增殖；骨骼修复将在软骨细胞持续增殖和分化的伴随下进行。总之，骨痂中软骨细胞的增殖与骨骼修复密切相关。骨折愈合的其他特征和阐释将为后续旨在确定骨骼修复机制的研究奠定基础。
