中文摘要：

目的应用显微CT研究去卵巢大鼠胫骨松质骨随时间延长骨小梁密度及微结构的变化。方法50只7月龄雌性SD大鼠随机分为基线组10只、去卵巢组（OVX）和假手术组（sham）各20只。基线组10只实验开始时即处死，OVX组和sham组分别在手术后3周、15周各处死10只，分离保存左侧胫骨，行显微CT扫描。扫描完成后选取距生长板远端0．8mm、层厚0．5mm的骨组织为兴趣区域，进行三维重建，获取骨小梁三维结构图像，并进行松质骨定量分析。结果OVX组与sham组的体积骨密度、骨体积分数（BVF）、骨小梁数量（Tb．N）和骨小梁连接密度3周较15周显著下降，结构模型指数明显增高，提示骨小梁板状形态结构的衰减。3周时OVX组组织骨密度显著低于sham组，15周时两组间无明显差异；而3周时骨小梁间隔与sham组无明显差异，15周时则显著增高。随着去卵巢时间的延长，大鼠胫骨松质骨BVF、Tb．N和骨小梁连接密度进行性下降，但骨小梁厚度（Tb．Th）和组织骨密度却明显升高。15周时Tb．Th为（0．081±0．013）mm，显著高于3周时的（0．061±0．006）mm和基线组的（0．061±0．010）mm；15周时组织骨密度为（691．2±35．3）mg／mm^3，显著高于3周时的（624．4±34．4）mg／mm^3和基线组的（638．8±61．0）mg／mm^3。结论大鼠去卵巢后胫骨松质骨骨量明显丢失，微结构发生改变，而残余骨小梁会因代偿性肥厚和组织骨密度的升高而得到加强。

英文摘要：

Objective To investigate the time-related compensatory behavior of trabecular bone in BMD and microstructure in ovariectomized rats. Methods Fifty seven-month-old female SD rats were recruited： ten of them were sacrificed as the baseline group; and the others were randomly assigned to ovariectomy （OVX） or sham-operation group, and each group included 20 rats. The left tibiae were harvested in the baseline group at the beginning, third week and fifteenth week post-operation in OVX and sham-operation groups respectively. A high resolution micro-CT was used to identify the densimetric and microstructural properties of trabeuclae in the proximal metaphysis of tibia. Results Compared with the sham rats at each time-point, there was a significant decrease in the volumetric BMD, bone volume fraction （BVF）, trabecular number （Tb.N） and trabecular connectivity （Conn.D） in the trabecular bone of the OVX rats. There was also a significant increase in the structure model index, indicating more rode-like trabeculae occurring. The tissue BMD of the OVX rats was lower than that of the sham rats at the third week, and yet it had no significant difference between two groups at the fifteenth week. Trabecular separation of the OVX rats was not significantly different from that of the sham rats at the third week, but was greatly higher at the fifteenth week. A time-related analysis within the OVX groups showed there was a significant declination in BVF, Tb.N and Conn.D, but both trabecular thickness （Tb.Th） and the tissue BMD were increased significantly. The mean value of Tb.Th at the fifteenth week was （0.081±0.013） mm, and significantly higher than that at the third week （0.061±0.006） mm or at the baseline （0.061±0.010） mm. So did the tissue BMD, the mean value at week 15, week 3 and the baseline was （691.2±35.3） mg/mm^3, （624.4±34.4） mg/mm^3 and （638.8±61.0） mg/mm^3 respectively. Conclusion Although estrogen-deficiency caused bone loss and microstructure deteriorations in the t