Testosterone Propionate投与後のラット睾丸における組織学的ならびに組織動態論的研究

Abstract

To examine the changes occurring in the testis in the rebound phenomenon, adult male Wistar rats were treated with 0.3 mg of testosterone propionate (TP) daily for 39 days. Observations were made at 0, 13, 26, 52 and 78 days following the TP treatment. The response of the testis was investigated histologically and was also analyzed using the tissue kinetic technique. No obvious changes in body weight observed but the testicular weight of the TP treated rats was half that of the control testis by the time TP treatment was terminated. However, from that time onward, the testicular weight started to increase. By the 78th day it was heavier than that of control. The weight responses of the seminal vesicle and prostate were just the reverse of that displayed by the testicle. The histological changes in TP treated rats were as follows: Soon after treatment, the diameter of the seminiferous tubule decreased and the spermatids were either absent or present in small numbers. No histological changes were seen in the seminiferous epithelium and Sertoli cells in themselves. The interstitial tissue was atrophic. The test group recovered from any TP induced changes, that is, there were no histological differences between the group on the 78th day after treatment and the control group. Spermatogenesis was measured by determining the relative number of germ cells in round tubular cross sections at stage VII of the seminiferous epithelium cycle. The relative number of type A spermatogonia and preleptotene spermatocytes remained similar to the control value in rats with maximal testicular atrophy due to TP treatment. When the TP injections were terminated, the relative numbers of pachytene spermatocytes and step 7 spermatids were 70% and 51 % of the control group, respectively. However, 78 days after TP treatment, the relative number of pachytene spermatocytes and step 7 spermatids were 120% and 160% of the control group, respectively. These changes demonstrate the "rebound phenomenon". Autoradiographic study using 3H-thymidine revealed that there was no great difference in the duration of seminiferous epithelium cycle between the TP treated group and control group. There was a slight distribution of the most advanced cells when the TP injections ended. In order to conclude that there were definite changes in the duration o[ the spermatogenesis, it is necessary to conduct a more precise experiment. It can be concluded from these observations that TP injection to adult male Wistar rats induced the "rebound phenomenon"; the most remarkable changes were seen in the relative number of pachytene spermatocytes and spermatids.