Seminiferous epithelium cycle and its duration in capybaras (Hydrochoerus hydrochaeris)

Although capybara is the largest rodent in the world and largely distribute d in Central and South America, there is no report in the literature concer ning the cycle of seminiferous epithelium in this species. in the present s tudy, the length of spermatogenic cycle was estimated using intratesticular injections of tritiated thymidine. Animals were sacrificed at 1 h, 8 days, and 17 days after injections. The duration of one spermatogenic cycle in c apybaras is 11.9 +/- 0.1 days (SEM). Spermatogenesis was estimated to last 53.6 days, when considering that the total duration of spermatogenesis take s about 4.5 cycles of seminiferous epithelium. The approximate life span of primary spermatocytes is 19.1 days, while spermiogenesis lasts 16.7 days. Staging in capybaras was based on the spermatid nuclei shape and location o f spermatids, named tubular morphology method, which consists of 8 stages i n all species, The relative stage frequencies in capybaras, based on the an alysis of approximately 200 cross sections of seminiferous tubule for each of the ten animals were as follow: stage 1: 14.0 +/- 1.5%; stage 2: 15.1 +/ - 1.0%; stage 3: 15.7 +/- 1.1%; stage 4: 14.6 +/- 1.1%; stage 5: 8.7 +/- 0. 7%; stage 6: 7.0 +/- 0.7%; stage 7: 9.4 +/- 0.9%; stage 8: 15.5 +/- 1.0%, T he pre-meiotic, meiotic and post-meiotic phases relative frequencies were 4 4.8%, 14.6% and 40.6%, respectively, Compared to most rodents investigated so far, the duration of spermatogenesis in capybaras is relatively long.