中文摘要：

目的 观察大鼠腭中缝在扩张力作用早期的细胞凋亡现象，探讨细胞凋亡在腭中缝骨改建启动过程中的意义。方法 选用4周龄健康雄性Wistar大鼠25只，随机分成对照0、1、2d组和实验加力1、2d组，每组各5只。用两眼簧扩弓器施加扩张力（约50g／0．49N）于实验加力组大鼠的腭中缝。于加力后1d、2d通过苏木素-伊红染色观察腭中缝组织形态学的改变，TUNEL法观察腭中缝组织中凋亡细胞的变化。结果 加力1d后腭中缝组织明显扩宽，腭中缝边缘的骨细胞凋亡数比对照组明显增多，加力2d后腭中缝边缘细胞大量增殖，凋亡骨细胞数有所减少，但仍多于对照组。结论 细胞凋亡在扩张腭中缝组织改建的启动过程中有着重要的生物学意义。

英文摘要：

Objective To detect the apoptosis cell in the maxilla palatal suture of rat during the early expansion period and discuss the significance of apoptosis in the suture remodeling after the expansion. Methods Twenty-five four-week-old Wistar rats were devided into two experiment groups and three control groups randomly （five rats each group）. A rectangular orthodontic appliance was set between the right and left upper molars of experiment rats with 50 g of initial expansional force. The sequence of histological changes in the midpalatal suture cartilage of animals was detected by Hematoxyhn-eosin staining. Apoptosis cells were tested by TUNEL assay. Results One day after application of the force, the pre-existing cartilage was separated laterally. Mesenchymal cells with stretched shapes were arranged parallel to the expansional force and filled the center of the suture. Apoptosis cells increased significantly along the inner lateral side of the cartilaginous tissue in expansion group, exhibiting strong fluorescence for TUNEL assay, compared with the control group. Conclusions These findings indicated that apoptosis may play a significant role in the initial procedure of palatal suture remodeling after the apphcation of expansional force.