Testicular histomorphometric patterns and spermatogenesis dynamics of Oecomys bicolor tomes, 1860 (Rodentia: Cricetidae).

Although the order Rodentia does not present a high risk of extinction compared to mammals as a whole, several families demonstrate high levels of threat and/or data deficiency, therefore highlighting the need for targeted research and the application of ecological and reproductive data to the development of conservation actions. The order Rodentia, the largest among mammals, includes 9 families, and the family Cricetidae is the most diverse of the Brazilian rodents. In Brazil, 12 of the 16 genera of Oecomys are found. Oecomys bicolor is known in Brazil as the 'arboreal rat' and is, found in dry, deciduous and tropical forests. The mean body weight of Oecomys bicolor was 35.8 g and the gonadal, tubular and epithelial somatic indexes were, 0.53%, 0.47% and 0.37%, respectively. Seminiferous tubules volume density was 89.72% and the mitotic and meiotic indexes corresponded to 8.59 and 2.45 cells, respectively, and the yield of spermatogenesis was 23.83 cells. The intertubular compartment represented 10.28% of the testis parenchyma and around 5% of the interstitial space was occupied by Leydig cells, whose number per gram of testis was 11.10 × 107 cells. By evaluating the biometric and histomorphometric characteristics of the testis, there is evidence that this species has a high investment in reproduction. Due to the high contribution of the seminiferous epithelium and the intertubular compartment in this species, compared to the others of the same family, it is possible to infer that the species Oecomys bicolor has a promiscuous reproductive behaviour.

Descriptive morphometry and stereology in accessing the testis structure and function of the marsupial Philander frenatus (Olfers, 1818) (Didelphimorphia: Didelphidae).

Philander frenatus is an important marsupial for the maintenance and conservation of the Atlantic Rainforest, however, it has biological characteristics that are still little explored. The study of the reproductive biology is an important key to understand the species reproductive strategies and to improve the development of conservation and management activities. The present study aimed to conduct a histological and morphometric investigation of the testis structure and function of P. frenatus. The average body and testicular weight were 445 g and 0.74 g, respectively, with a gonadosomatic index of 0.17%. The seminiferous tubules occupying 64.95% of the organ, totalising 9.26 m per gram of testis. The tubulesomatic and epitheliumsomatic indexes were 0.10% and 0.07%, respectively. Philander frenatus showed cell loss of approximately 98% during the proliferative phase and the spermatogenic yield was 10.3 cells. The high loss during the mitotic phase contributed to the low spermatogenic yield. The testicular parenchyma was composed of 35% of intertubular components, one of the highest proportions observed in mammals. Leydig cells were responsible for approximately 25% of the testes, followed by lymphatic space (6.44%), blood vessels and connective tissue (4% together). The organisation of the intertubular components resembles the Fawcett III category. The volume and number of Leydig cell per gram of testis were 2,627.12 µm3 and 91.28 × 106 cells, respectively. High investment in the intertubular compartment, specifically number and volume of Leydig cells in P. frenatus is consistent with territorial behaviour and polygynic mating system, which have greater androgenic capacity.

Colon cancer and swimming exercise: effect on wistar rat testes

This study was undertaken to determine whether colon cancer (CC) and chronic swimming exercise alter rat testis. Eleven weeks old rats were distributed into control group (n=6) and the groups that were induced to develop CC by dimethylhydrazine injections (nEG, EG0, EG2 and EG4; n=10 each group). In the group nEG, the rats did not swim, whereas groups EG0, EG2 and EG4, underwent a swimming program with distinct loads (0, 2 and 4% of body mass, respectively) for 35 weeks. The morphometry, stereology and cell counts showed damage caused by the CC on the germ epithelium. These results were noteworthy since this was the first report to associate the CC with testicular damage. Swimming exercise had no significant role in reducing, or increasing the CC effects on the testis, despite having slightly improved the testis structure of the exercised rats without load. In conclusion, CC caused testis impairment, which could not be avoided by the swimming exercise.

Histomorphometric evaluation of the neotropical brown brocket deer Mazama gouazoubira testis, with an emphasis on cell population indexes of spermatogenic yield.

Information on the reproductive biology of neotropical cervids is scarce. Therefore, the aim of this study was to perform biometric, histologic and stereologic analyses of the brown brocket deer Mazama gouazoubira testis, with an emphasis on the intrinsic yield and the Sertoli cell index. Seven adult males kept in captivity were used. The animals were immobilized; anesthetized and testicle fragments were obtained by biopsy incision. The material was fixed, processed and examined by routine histological methods for light microscopy. The average body weight was 17.2kg, from which 0.40% were allocated in gonads and 0.33% in seminiferous tubules, which represented 85.9% of the testis parenchyma. The mean albuginea width and volume were 345.7µm and 3.5mL (5.3% of the testicular weight), respectively. The mean mediastinum volume of both testicles was 1.0mL (1.5% of the testicular weight) and the testicular parenchyma volume corresponded to 93.1% of total testicular weight (64.9g). The seminiferous tubules diameter was 224.4µm, while the epithelium height was 69.6µm. On average, an adult brown brocket deer showed a total of 1418m of seminiferous tubules in both testicles (21.5m per gram of testis). Each stage I seminiferous tubular cross section contained 1.10 type A spermatogonia, 13.4 primary spermatocytes in pre-leptotene/leptotene, 13.7 spermatocytes in pachytene, 48.8 round spermatids and 3.7 Sertoli cells. The general yield of spermatogenesis was 44.7 cells and the Sertoli cell index was 13.2. The qualitative and quantitative description of testicular histology of brown brocket deer help to understand its spermatogenic process and to establish parameters for the reproductive biology of this wild species. Furthermore, the data from the present research will help further studies using other species of Brazilian cervids, especially endangered ones, making an additional effort to the species preservation.