Please cite this article in press as: Morais, A.C.T., et al., The tubular compartment and the spermato- genic dynamics of the wild rodent Oxymycterus nasutus (Rodentia: Cricetidae). Anim. Reprod. Sci. (2014), http://dx.doi.org/10.1016/j.anireprosci.2014.06.027 ARTICLE IN PRESS G Model ANIREP-5006; No. of Pages 10 Animal Reproduction Science xxx (2014) xxx–xxx Contents lists available at ScienceDirect Animal Reproduction Science jou rn al hom epage : w ww.elsevier.com/locate/anir eprosci The tubular compartment and the spermatogenic dynamics of the wild rodent Oxymycterus nasutus (Rodentia: Cricetidae) Ana Carolina Torre Morais a , Maytê Koch Balarini a , Elizabeth Oliveira Lopes a , Tatiana Prata Menezes a , Fernando Marques Quintela b , Danielle Barbosa Morais c , Marcos de Lucca M. Gomes a , Sérgio Luis P. da Matta a,∗ a Department of General Biology, Federal University of Vic ¸ osa (UFV) - Vic ¸ osa, Minas Gerais, 36570-000 Brazil b Department of Animal Biology, Federal University of Rio Grande do Sul (UFRGS) - Porto Alegre, Rio Grande do Sul, 91501-970 Brazil c Department of Morphology, Federal University of Rio Grande do Norte (UFRN) - Natal, Rio Grande do Norte, 59078-900 Brazil a r t i c l e i n f o Article history: Received 24 March 2014 Received in revised form 23 June 2014 Accepted 24 June 2014 Available online xxx Keywords: Sertoli cell Spermiogenesis Seminiferous epithelium Testicle morphology Morphometry Stereology a b s t r a c t Despite the order Rodentia present worldwide distribution and large number of species in the Brazilian fauna, detailed studies on testicular morphophysiology are still scarce. There- fore, this study aimed to analyze the dynamics of the spermatogenic process of Oxymycterus nasutus using morphometrical and stereological tools. Testicles from ten sexually mature males were used, showing a gonadosomatic index of 0.89%. The testicular parenchyma showed one of the highest tubulesomatic indexes reported among wild rodents – 0.82% – from which 65.12% was allocated into seminiferous epithelium. The average tubular diam- eter was 249.89 m, whereas the epithelium height was 62.47 m and the total length was 18.62 m per gram of testis. Eight different stages of the seminiferous epithelium cycle were described. Stage 1 was used for counting the germ cell population as well as the Sertoli cells. On average, 3.47 type-A spermatogonia, 24.39 primary spermatocytes in prelep- totene/leptotene, 24.13 primary spermatocytes in pachytene, 68.38 round spermatids and 7.33 Sertoli cells were found per tubular cross section. There were 91.02 × 10 6 Sertoli cells per gram of testis and each cell was able to support 9.33 spermatids and 16.43 germ cells. The coefficient of spermatogonial mitosis was 7.02, while 2.83 spermatids were produced for each primary spermatocyte in pachytene. The overall efficiency of spermatogenesis was 19.70 cells, whereas the sperm reserve per gram of testis totalized 849.63 × 10 6 spermatids. Therefore, the presented data showed that O. nasutus shows a high energetic investment in reproduction, corroborating the findings for other species of the Cricetidae family. © 2014 Published by Elsevier B.V. ∗ Corresponding author at: Laboratório de Biologia Estrutural, Depar- tamento de Biologia Geral, CCB-UFV. Av. PH Rolfs, sn. CEP: 36570-000, Brazil. Tel.: +55 31 3899 3361; fax: +55 31 3899 2549. E-mail addresses: smatta@ufv.br, sergiomatta@ufv.br (S.L.P.d. Matta). 1. Introduction The order Rodentia shows a worldwide distribution, and contains species that can be found in all habitats, from arctic tundra to deserts (Honeycutt, 2004). They are abun- dant in tropical forests, predating and dispersing seeds and seedlings (Cáceres and Monteiro-Filho, 2000; Vieira et al., 2003), besides being an important part of the food chain by serving as preys for eagles, snakes and carnivorous http://dx.doi.org/10.1016/j.anireprosci.2014.06.027 0378-4320/© 2014 Published by Elsevier B.V.