OBJECTIVETo examine the differences in the expressions of c-kit, HIWI and vimentin in the testis and epididymis of rats aged different months, investigate the regular changes in the expression of characteristic molecules in the ripening and senescent process of the testis and epididymis, and provide experimental evidence for studies on the aging of the male reproductive system.

METHODSSprague-Dawley male rats were divided into a young group (6-month-old, n=10), an adult group (12-month-old, n=10) and an aged group (24-month-old, n=10). The immunohistochemical SP method was used to examine c-kit, HIWI and vimentin in the testis and epididymis of the rats.

RESULTSThe positive immunohistochemical reaction to c-kit was observed mainly in spermatogonia, weakly in other cells and also in the epithelia and lumens of the epididymis. The abundant expression of HIWI was detected in all stages of spermatogenic cells in the testis and epididymis of the 6-month-old and 12-month-old rats. Moreover, spermatogonias and primary spermatocytes displayed intense expression. Sertoli cells, Leydig cells, myoid cells and vascular endothelial cells (VEC) were also HIWI-positive cells. But the positive expression decreased with age in the testis and epididymis of the 24-month-old rats (P > 0.05). vimentin expression was weak in the testis and epididymis of the 6-month-olds but increased significantly in the 24-month-olds (P > 0.01).

CONCLUSIONThe expressions of c-kit and HIWI decreased in the testis and epididymis of the 24-month-old rats, while vimentin expression increased markedly with age. The results suggest that the aging of the testis and epididymis is closely related to the abnormal transduction of cell signals.