Researches on the regenerating thymus after irradiation-to find out the responsible factors which may regulate the thymic epithelial cell regeneration

（1）对大鼠胸腺进行辐射损伤的形态学观察。与6戈伊照射相比，8戈伊照射后胸腺细胞恢复较慢。尽管在从6戈伊和8戈伊照射恢复时胸腺中的发现是相似的。（2）P63分子在大鼠表皮未成熟上皮细胞中特异性表达。在正常大鼠胸腺中，p63分子被零星地检测到，特别是在被膜下区域。照射后，胸腺p63阳性上皮细胞的相对数量增加。这表明，照射后，胸腺内不仅胸腺细胞被破坏，而且胸腺上皮细胞也被破坏，除胸腺细胞突然再生外，甚至胸腺上皮细胞也可能再生。不同剂量的辐射对胸腺上皮细胞的损伤程度不同，在辐射后及再生过程中，胸腺上皮细胞可能发生不可逆的变化，8 Gy辐射仅使胸腺重量恢复65%。（3）6戈伊和8 Gy照射胸腺细胞因子信息表达不同。特别地，与6戈伊照射的胸腺相比，IL-6的信使水平在8戈伊照射的胸腺中显著较低。当在从照射恢复的时间测量消息时。（4）原代培养的胸腺上皮细胞经6戈伊或8戈伊照射后，体外诱导胸腺细胞分化。然而，根据我们的实验，在6戈伊和8戈伊照射之间没有观察到统计学上的显著差异。

(1)Rats were irradiated and the thymus was examined morphologically. Comared to the 6 Gy irradiation, in the case of 8 Gy irradiation, the recovery of thymocytes was slower. although the findings in the thymus at the time of recovery from both 6 Gy and 8 Gy irradiations were similar.(2)P63 molecule can be detected specifically in the immatrure epithelial cells in the rat epidermis. In the normal rat thymus, p63 molecules were detected sporadically, especially in the region of the subcapsular area. After irradiation, the relative number of p63 positive thymic epithelial cells increased in number. These suggest that after irradiation, in the thymus, not only the thymocyte but also the thymic epithelial cell were destroyed and in addition to the abrupt thymocyte regeneration, even regeneration of the thymic epithelial cells may take place. Following the different doses of irradiation, the degree of the damages on the thymic epithelial cells may be different and subsequently, after irradiation and on the process of regeneration, some irreversible changes may be induced on the thymic epithelial cells and resulted in only 65% of recovery in the thymus weight in the 8Gy irradiation.(3)The cytokine message expressions were different between 6 Gy and 8 Gy-irradiated thymi. Particularly, the message levels for Il-6 were significantly low in the 8Gy irradiated thymus compared to those in 6 Gy irradiated thymus., when the messages were measured at the recovered time from the irradiation.(4)The primary cultured thymic epithelial cells, which were irradiated at the irradiation doses of either 6 Gy or 8 Gy were used for induction of thymocyte differentiation in vitro. However, from our experioments statistically significant differences were not observed between 6 Gy and 8 Gy irradiation.