Spermatic granulomata are experimentally induced in epididymides of mice receiving high-dose testosterone implants. I. A light-microscopical study.

It is known that a spermatic granuloma is induced by the inflammatory reaction following leakage of spermatozoa outside the germ cell ducts and is the main clinical complication of vasectomy. In the present study, we found that spermatic granulomata were experimentally induced in the epididymides of mice treated with high-dose testosterone. Testosterone powder (0.02, 0.2, or 2 mg per gram body weight) was implanted into ICR male mice, which were then killed from 7 to 63 days after the treatment for histological examination at the light-microscopic level. The results showed that the testis exhibited little or no degenerative change; however, the epididymides were frequently affected by spermatic granulomata after day 35 in mice implanted with high-dose testosterone (2 but not 0.2 or 0.02 mg per gram body weight). Observation of the early histological changes revealed that the ductal epithelium of the epididymides became vacuolated around day 25. Thereafter, the basement membrane of the epididymal ducts was ruptured after day 30, followed by leakage of spermatozoa into the adjacent interstitial tissue. The extravasated spermatozoa were then surrounded by macrophages (= epithelioid cells) and lymphocytes, resulting in the formation of a spermatic granuloma. In contrast, other mice treated with the same dose of deoxycorticosterone or estradiol did not show the induction of spermatic granulomata. Therefore, this study demonstrated that a spermatic granuloma is specifically formed in the epididymis by testosterone and that the lesion is started by vacuolation of the epididymal duct epithelium.