Histomorfometria testicular e ciclo do epitélio seminífero nos roedores silvestres Oxymycterus rufus e Oxymycterus nasutus (Rodentia: Cricetidae)

• Autor(a) principal: Morais, Ana Carolina Torre
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/278
• topic: Espermatogênese em animais; Histologia; Roedor; Oxymycterus rufus; Oxymycterus nasutus; Spermatogenesis in animals; Histology; Rodent; Oxymycterus rufus; Oxymycterus nasutus; CNPQ::CIENCIAS BIOLOGICAS::BIOLOGIA GERAL

The rodents are the most diverse order of mammals. They are distributed worldwide, from arctic tundra to deserts. However, little is known about the reproduction of wild species, since rodents, as well as other mammals, are important parts in the dynamics of the forests they inhabit. Thus, the objective of the present study was to describe the process of spermatogenesis of the wild rodents Oxymycterus rufus and Oxymycterus nasutus in order to provide relevant information on testicular activity of these species. Five adult specimens of O. rufus were collected in an Atlantic Forest fragment, whereas 10 adult O. nasutus were collected in a Pampa biome. Euthanasia was performed by anesthetic overdose and testicular fragments were collected, fixed and routinely processed, being analyzed under light and transmission electron microscopy. The body weight of O. rufus and O. nasutus were 82.28 and 58.30 g, respectively, whereas 0.47 and 0.89 % of these were allocated into testes and 0.40 and 0.82 % into seminiferous tubules. The proportions of seminiferous epithelium were 0.35 to 0.56 %, respectively. The length of the seminiferous tubules were 34.93 and 18.62m/g, for O. rufus and O. nasutus, respectively, and the stages of the seminiferous epithelium cycle followed the pattern described for other wild rodents. For O. rufus, the duration of the seminiferous epithelium cycle was determined, being each cycle corresponding to 6.58 days while all the spermatogenic process lasted 29.61 days. The number of Sertoli cells per gram of testis was 232.40 x10 6 and 91.02 x10 6 in O. rufus and O. nasutus respectively, and the daily sperm reserve was 962 x10 6 and 849.64 x10 6 , respectively. The interstitium occupied 9.09 and 4.81 % of the testes of O. rufus and O. nasutus, respectively, and followed the type I organization pattern described by Fawcett. The Leydig cells were the most abundant element in the interstitium (117.23 x10 6 per gram of testis in O. rufus and 40.77 x10 6 per gram of testis in O. nasutus), and the leydigsomatic indexes were 0.018 and 0.019 % in O. rufus and O. nasutus, respectively. Therefore, we concluded that O. rufus and O. nasutus show high efficiency of spermatogenesis with high proportion of seminiferous tubules in the testicular parenchyma, abundant Sertoli cells per gram of xitestis and high sperm reserve, thus demonstrating high energy investment in sperm production, which is compatible with animals displaying promiscuous mating system.