Age-dependent Decrease in Incidence of Rat Sperm Granulomas Induced by L-Cysteine

Abstract

The pathogenesis of sperm granulomas is very complicated, and leakage of spermatozoa into extraluminal tissues is regarded as a crucial event. We previously reported that sperm granulomas were frequently induced in the epididymides of pubertal rats by excessive dose of L-cysteine (L-Cys). Here, we compared the incidence of sperm granulomas between L-Cys-treated pubertal (6-week-old) and adult (11-week-old) rats by intraperitoneally injecting daily with L-Cys (800 mg/kg body weight) for 4 weeks. L-Cys-induced sperm granulomas were seen in 6 rats of 10 L-Cys-treated pubertal rats, whereas only one rat in 40 L-Cys-treated adult rats developed a sperm granuloma, indicating age-dependent decrease in the frequency. In L-Cys-treated pubertal rats, additionally, small ducts (indicative of immaturity), dilated ducts, and interstitial edema were frequently seen, but such findings were rarely present in L-Cys-treated adult rats. The accumulation of spermatozoa in epididymal ducts was often observed both in L-Cys-treated pubertal and adult rats. These findings indicated that the administration with a large amount of L-Cys might have disturbed the luminal microenvironments, with greater influence on pubertal rats than adult rats. Particularly, the findings, that the incidences of small ducts and sperm granulomas were high in L-Cys-treated pubertal rats and low in L-Cys-treated adult rats, suggested that the prerequisite for sperm granuloma formation might be associated mainly with the delayed maturation of epididymal ducts seen exclusively in pubertal rats due to excessive dose of L-Cys.