The Duration of the Cycle of the Seminiferous Epithelium is Altered by Administration of 2,5‐Hexanedione in the Adult Sprague‐Dawley Rat

Abstract

ABSTRACT: The duration of the cycle of the seminiferous epithelium is believed to be under genetic control rather than being influenced by other factors. However, the frequencies of certain spermatogenic stages—reflecting their relative durations—can be altered under various conditions including treatment with the n‐hexane metabolite, 2,5‐hexanedione (HD). To investigate whether HD administration alters the duration of the spermatogenic process, adult Sprague‐Dawley rats were exposed to vehicle (n = 20) or 1% HD dissolved in the drinking water (n = 40) throughout a period of 29 days. On day 17, 100 mg/kg of 5‐bromodeoxyuridine (BrdU) was given intraperitoneally; 3 hours later one testis was removed, and the remaining testis was excised 12 days later. BrdU was localized in Bouin's‐fixed, Paraplast‐embedded testes using immunogold‐silver‐staining, and sections were counterstained with periodic acid‐Schiff and hematoxylin to permit identification of the spermatogenic stages. HD treatment reduced weights of body, testis, and epididymis (P < 0.05) but had no effects on serum levels of follicle‐stimulating hormone or testosterone. The seminiferous epithelium was vacuolized, and spermatogenesis was affected to various degrees. HD significantly reduced the frequency of stage VII tubules (P < 0.01) and increased the frequency of stage IX and stage×tubules (P < 0.05). Furthermore, HD reduced the stage‐dependent progression of BrdU‐labeled germ cells. By day 29, BrdU‐positive germ cells were seen in 13% of stage IX control tubules, whereas in HD‐treated animals BrdU‐labeled germ cells were not present in stage IX tubules and were found in only 2–3% of stage VIII tubules; the calculated duration of the spermatogenic cycle was significantly increased (P < 0.01) in the HD‐administered animals (13.43 ± 0.10 vs. 12.37 ± 0.05 days). These findings demonstrate (1) that the duration of the cycle of the seminiferous epithelium can be altered experimentally in the adult Sprague‐Dawley rat and (2) that changes in the frequency of spermatogenic stages can be associated with a change in the duration of the spermatogenic process. 1995 American Society of Andrology