目的　研究 bax基因在正常小鼠睾丸中的表达、定位及隐睾所导致的改变。　方法　以 Western-blotting印迹法从蛋白水平检测 bax基因在正常小鼠睾丸及实验性隐睾中的表达、变化 ;原位杂交技术及 Northern杂交法从 m RNA水平检测 bax基因在小鼠生精上皮中的定位及隐睾所导致的改变。　结果　 bax基因在正常小鼠睾丸中有弱表达 ,实验性隐睾导致其表达明显增强 ,表达细胞主要为精母细胞、精原细胞和精子细胞 ,支持细胞和间质细胞未见表达。　结论　 bax基因可能在生精细胞主动退化的调节中起着重要作用 Objective To study the expression of bax gene in testis of normal mice and its location and the changes caused by cryptorchidism. Methods Western blotting was used to detect the expression of bax gene in normal testes and experimental cryptorchidism from protein level. The in situ hybridization and Northern blotting were used to detect the expression of bax gene in mouse seminiferous epithelium In the positioning and changes caused by cryptorchidism. Results The bax gene was weakly expressed in testis of normal mice. The expression of bax gene was significantly increased in experimental cryptorchidism. The expression of bax gene was mainly in spermatocytes, spermatogonia and sperm cells, but not in supporting cells and stromal cells. Conclusion The bax gene may play an important role in the regulation of active degeneration of spermatogenic cells