中文摘要：

目的探讨X射线躯体辐射对小鼠胸腺重量、细胞计数及细胞凋亡的影响。方法2．0Gy与．075GyX射线照射后0、2、4、8、16、247及48h，采用直接称重、显微镜下计数、流式细胞术分别检测小鼠胸腺的重量、细胞数及细胞凋亡情况。结果2.0GyX射线照射后小鼠胸腺重量先升高后下降，而胸腺细胞数显著下降，到48h两者均降至最低水平；而胸腺细胞凋亡显著增加，48h达到最高水平。0．075Gy照射后胸腺重量及胸腺细胞数显著升高而胸腺细胞凋亡没有明显变化。结论高剂量辐射（HDR）作用下胸腺的重量、细胞计数下降，而胸腺细胞凋亡增加，对免疫系统有明显的抑制作用。低剂量辐射（LDR）可以在一定程度上促进胸腺的重量增加、细胞数目增多，细胞凋亡减少，有免疫兴奋作用。

英文摘要：

Objective To study the effect of mouse WBI （ whole body irradiation, WBI ） with X-rays on weight, cell number and apoptosis of the thymus. Methods Weighing, microscope count and flow cytometry were respectively used to detect the changes in weight, cell number and apoptosis of the mouse thymus at different times （0, 2, 4, 8, 16, 24and48h） after WBI with X-rays of 0.075 and2.0Gy. Results Theweight of thymus in mice firstly increased and then decreased; cell counts decreased gradually in a time-dependent manner; both reached their nadir at 48h; while the apoptosis of thymocytes increased in a time-dependent manner and peaked at 48h after WBI with X-rays 2.0Gy. The weight and cell number of thymus were promoted significantly and apoptosis did not change significantly after WBI with X-rays 0.075Gy. Conclusion HDR could reduce the quality of thymus, decrease cell accounts and enhance apoptosis. LDR could improve the quality of thymus, increase cell accounts and inhibit apoptosis to some extent. HDR could significantly inhibit immune system while LDR could stimulate immune system.