RESUMO

Despite the singular morphology of the male genital system and the different reproductive strategies of marsupials, little emphasis has been given to the testis morphology and spermatogenic kinetics in this mammalian order. The present study aimed to investigate the testis function and the duration of spermatogenesis in the southeastern four-eyed opossum, Philander frenatus. Testes of six adult males were routinely processed for histological and stereological analyses. In order to determine the duration of spermatogenesis, intratesticular injections of tritiated thymidine were performed 1h, 13days and 21days before the sacrifice. Based on the development of the acrosomic system, ten stages of the seminiferous epithelium cycle were characterized. The mean body and testis weights for the P. frenatus were respectively 326±20g and 0.4±0.05g, providing a gonadosomatic index of 0.3±0.02%. The most advanced germ cell types labeled at 1h, 13days and 21days after thymidine injections were, respectively, preleptotene spermatocytes at stage IV, pachytene spermatocytes at stage IV and diplotene spermatocytes at stage IX. Based on the stages frequencies and the most advanced labeled germ cells, each spermatogenic cycle and the entire spermatogenic process lasted respectively 13.5±0.5 and 60.9±2.4days. When compared to the vast majority of eutherian mammals already investigated, these data indicate that the Philander frenatus presents a relatively long duration of spermatogenesis.

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RESUMO

Yellowish myotis, Myotis levis, is a seasonal, epididymal sperm-storing Neotropical vespertilionid. In the dry season, males show simultaneous testis regression and sperm storage in cauda epididymis, enabling them to mate during this season. In this study, we investigated seasonal variations in body mass, diameter and height of seminiferous tubules and nuclei of Leydig cells in a population of southeastern Brazil. We also determined the frequencies of the stages of the seminiferous epithelium cycle (SEC) of mature individuals of this population. Body mass and diameter of Leydig cell nuclei showed no significant differences between dry and rainy seasons and stages of annual reproductive cycle; however, all other morphometric parameters varied significantly. The relative cumulative frequency of pre-meiotic stages of the SEC (1-3) was 51%, of meiotic stage (4) was 2% and of post-meiotic stages (5-8) was 47%. We confirmed that the yellowish myotis presents seasonal sperm production as revealed by testis regression and epididymal sperm storage during the dry season.

Assuntos

RESUMO

Species richness and abundance of bats were studied in four nature reserves, including a karst area which has many potential rocky shelters for bats, such as caves and rock crevices. The reserves were located in the greater Belo Horizonte metropolitan area, one of the most populated regions of Brazil, within the Atlantic Forest, and Cerrado (Brazilian savanna) ecological domains. Bats were sampled using mist-nets and, in the karst area, also by active searches in shelters. A total of 1,599 bats were captured representing 30 species belonging to four families. There was little similarity among the four chiropteran faunas. The greatest species richness was found in the karst area with 22 species recorded whereas richness estimates in the other areas indicated the need for further studies. Two hundred and sixty-five individuals of 14 species were captured from 56 shelters. Most of the shelters were frequently used for diurnal roosts, and all the bats found belonged to the Phyllostomidae, with the exception of Myotis nigricans (Vespertilionidae), Nyctinomops laticaudatus (Molossidae) and Peropteryx macrotis (Emballonuridae). The sanguinivorous Desmodus rotundus was the most common species in the shelters. The results of this study demonstrate the importance of maintaining multiple protected areas to ensure a representative fauna of bats in a region characterized by a vegetation transition zone and with intense economic activity and high environmental impact. This study also demonstrates the importance of rock shelters for maintaining local bat richness and the importance of active searches for bats in their diurnal roosts for a more thorough sampling of the bat fauna at a given locality.

Assuntos

RESUMO

Species richness and abundance of bats were studied in four nature reserves, including a karst area which has many potential rocky shelters for bats, such as caves and rock crevices. The reserves were located in the greater Belo Horizonte metropolitan area, one of the most populated regions of Brazil, within the Atlantic Forest, and Cerrado (Brazilian savanna) ecological domains. Bats were sampled using mist-nets and, in the karst area, also by active searches in shelters. A total of 1,599 bats were captured representing 30 species belonging to four families. There was little similarity among the four chiropteran faunas. The greatest species richness was found in the karst area with 22 species recorded whereas richness estimates in the other areas indicated the need for further studies. Two hundred and sixty-five individuals of 14 species were captured from 56 shelters. Most of the shelters were frequently used for diurnal roosts, and all the bats found belonged to the Phyllostomidae, with the exception of Myotis nigricans (Vespertilionidae), Nyctinomops laticaudatus (Molossidae) and Peropteryx macrotis (Emballonuridae). The sanguinivorous Desmodus rotundus was the most common species in the shelters. The results of this study demonstrate the importance of maintaining multiple protected areas to ensure a representative fauna of bats in a region characterized by a vegetation transition zone and with intense economic activity and high environmental impact. This study also demonstrates the importance of rock shelters for maintaining local bat richness and the importance of active searches for bats in their diurnal roosts for a more thorough sampling of the bat fauna at a given locality.(AU)

Neste estudo, a riqueza e a abundância de espécies de morcegos foram estudadas em quatro reservas naturais, incluindo uma área cárstica com muitas cavernas e fendas em rochas, que constituem abrigos rochosos potenciais para os morcegos. As reservas encontram-se dentro da região metropolitana de Belo Horizonte-MG, uma das mais povoadas do Brasil, e dentro dos domínios de Floresta Atlântica e do Cerrado. Os morcegos foram amostrados com redes de neblina (mist-nets) e, na área cárstica, também foi realizada busca ativa por morcegos em seus abrigos. Foram capturados 1.599 morcegos de 30 espécies, pertencentes a quatro famílias. Houve pouca similaridade entre as faunas de quirópteros analisadas. A maior riqueza foi encontrada na área cárstica, com 22 espécies registradas com redes de neblina e em seus abrigos; entretanto, estimativas de riqueza indicaram a necessidade de mais estudos nas outras áreas. Do total amostrado, 265 indivíduos de 14 espécies foram capturados em 56 abrigos. A maioria dos abrigos era ocupada no período diurno e de uso frequente; os morcegos presentes eram filostomídeos, exceto Myotis nigricans (Vespertilionidae), Nyctinomops laticaudatus (Molossidae) e Peropteryx macrotis (Emballonuridae). O hematófago Desmodus rotundus foi o mais frequente nos abrigos. O resultado deste estudo indica a importância da manutenção de diferentes áreas para a conservação dos quirópteros em região caracterizada como zona de transição vegetacional e com intensa atividade econômica e impacto ambiental. Este estudo demonstra também a importância dos abrigos rochosos para a riqueza local de espécies e a importância de busca ativa por morcegos em seus abrigos diurnos para uma amostragem mais efetiva da fauna local destes quirópteros.(AU)

Assuntos

RESUMO

The spiny rat (Trinomys moojeni) is a rodent found in the Atlantic Forest, which is considered one of the most diverse and threatened biomes in the world. Knowledge on reproductive biology and physiology is critical to conservation and species management, allowing the prevention of extinction and the use of males in natural and artificial reproduction programs. The main objectives of the present study were to investigate the testis structure as well as spermatogenic and Sertoli cell efficiency in the spiny rat captured in the Caraça Natural Reserve, a fragment of the Atlantic Forest located in the State of Minas Gerais, Brazil. Ten sexually mature spiny rats were analyzed. Intraperitoneal injections of tritiated thymidine were administered to estimate duration of spermatogenesis. The testes were perfused-fixed in buffered glutaraldehyde and routinely processed for histological and morphometric analyses as well as the characterization of the stages of seminiferous epithelium cycle. Volume density (%) of seminiferous tubules and Leydig cells were 97 +/- 0.3 and 0.3 +/- 0.02, respectively. The duration of one spermatogenic cycle and total duration of spermatogenesis were 8.6 +/- 0.1 and 38.5 +/- 0.5 days, respectively. Due to the very great volume density of the seminiferous tubules, short duration of spermatogenesis, tubule length per gram of testis (approximately 40 m), great Sertoli cell efficiency (approximately 15 spermatids per Sertoli cell) and large number of Sertoli cells per testis gram (53 million), spermatogenic efficiency in the spiny rat (82 million) is by far the greatest of the mammalian species investigated thus far.

Assuntos