Resumo
Spermatozoon maturation involves an extense and complex process beginning with proliferation and differentiation of spermatogonia, passing through meiosis, and ending with spermiogenesis. The later event involves morphological and biochemical changes in order to transform spermatids into spermatozoa. Ultrastructural aspects of the spermiogenesis and testicular spermatozoa of the anuran Eupemphix nattereri (Steindachner, 1863) were analyzed by transmission electron microscopy. Spermiogenesis involves chromatin condensation and nuclear elongation, with visible cytoplasmic elimination. At this stage, a large amount of microtubules and glycogen can also be seen in Sertoli cell cytoplasm, surrounding each spermatid. The spermatozoon is fusiform and the acrossome forms a cap in the anterior region of the nucleus. A mitochondrial sleeve is found around the proximal portion of the tail. The tail presents an axonema with a 9+2 pattern, a justaxonemal fiber, an undulating membrane, and the absence of axial rod. This organization shows some similarities with species of the genus Physalaemus (Leiuperidae) such as P. biligonigerus (Cope, 1861), P. gracilis (Boulenger, 1883) and P. fuscomaculatus (Steindachner, 1864).
A maturação dos espermatozóides envolve um extenso e complexo processo que começa com a proliferação e diferenciação das espermatogônias, passa pela meiose e finaliza com a espermiogênese. Nessa fase, eventos envolvendo alterações morfológicas e bioquímicas transformam espermátides em espermatozóides. Aspectos ultra-estruturais da espermiogênese e do espermatozóide do anuro Eupemphix nattereri (Steindachner, 1863) foram analisados através de microscopia eletrônica de transmissão. A espermiogênese envolve condensação da cromatina e alongamento nuclear, com visível eliminação de citoplasma. Nesse estágio, grande quantidade de microtúbulos e glicogênio podem ser visualizados no citoplasma das células de Sertoli, rodeando cada espermátide. O espermatozóide é fusiforme e o acrossomo forma uma capa na região anterior do núcleo. A bainha mitocondrial é encontrada ao redor da porção proximal da cauda. A cauda apresenta o axonema com o modelo 9+2, uma fibra axonemal, a membrana ondulante e ausência de bastão axial. Esta organização apresenta algumas similaridades com espécies do gênero Physalaemus (Leiuperidae) como P. biligonigerus (Cope, 1861), P. gracilis (Boulenger, 1883) e P. fuscomaculatus (Steindachner, 1864).
Resumo
Spermatozoon maturation involves an extense and complex process beginning with proliferation and differentiation of spermatogonia, passing through meiosis, and ending with spermiogenesis. The later event involves morphological and biochemical changes in order to transform spermatids into spermatozoa. Ultrastructural aspects of the spermiogenesis and testicular spermatozoa of the anuran Eupemphix nattereri (Steindachner, 1863) were analyzed by transmission electron microscopy. Spermiogenesis involves chromatin condensation and nuclear elongation, with visible cytoplasmic elimination. At this stage, a large amount of microtubules and glycogen can also be seen in Sertoli cell cytoplasm, surrounding each spermatid. The spermatozoon is fusiform and the acrossome forms a cap in the anterior region of the nucleus. A mitochondrial sleeve is found around the proximal portion of the tail. The tail presents an axonema with a 9+2 pattern, a justaxonemal fiber, an undulating membrane, and the absence of axial rod. This organization shows some similarities with species of the genus Physalaemus (Leiuperidae) such as P. biligonigerus (Cope, 1861), P. gracilis (Boulenger, 1883) and P. fuscomaculatus (Steindachner, 1864).
A maturação dos espermatozóides envolve um extenso e complexo processo que começa com a proliferação e diferenciação das espermatogônias, passa pela meiose e finaliza com a espermiogênese. Nessa fase, eventos envolvendo alterações morfológicas e bioquímicas transformam espermátides em espermatozóides. Aspectos ultra-estruturais da espermiogênese e do espermatozóide do anuro Eupemphix nattereri (Steindachner, 1863) foram analisados através de microscopia eletrônica de transmissão. A espermiogênese envolve condensação da cromatina e alongamento nuclear, com visível eliminação de citoplasma. Nesse estágio, grande quantidade de microtúbulos e glicogênio podem ser visualizados no citoplasma das células de Sertoli, rodeando cada espermátide. O espermatozóide é fusiforme e o acrossomo forma uma capa na região anterior do núcleo. A bainha mitocondrial é encontrada ao redor da porção proximal da cauda. A cauda apresenta o axonema com o modelo 9+2, uma fibra axonemal, a membrana ondulante e ausência de bastão axial. Esta organização apresenta algumas similaridades com espécies do gênero Physalaemus (Leiuperidae) como P. biligonigerus (Cope, 1861), P. gracilis (Boulenger, 1883) e P. fuscomaculatus (Steindachner, 1864).
Resumo
The ability of certain species of bats to store viable spermatozoa in the cauda epididymis, for periods of many months beyond the end of spermatogenesis was first recognized over a century ago. However, information about the bat epididymis is still scarce or absent. Thus, this study aimed to characterize and to compare morphologically and morphometrically the regional histology of the epididymis of Eumops glaucinus and Molossus molossus (Chiroptera: Molossidae). Histologically, the epididymis of both species was subdivided into 4 segments: initial segment, caput, corpus and cauda. In comparing the two species, it was observed that the tubular and luminal diameters and percentage of interstitial tissue showed significant differences in all segments. The epithelial height, in both, is greater in the initial segment with a decrease until the cauda epididymis. In relation to the luminal diameter, both species showed a gradual increase from the initial segment to the cauda. The percentage of epithelium, lumen and interstitial tissue varied between both, sometimes M. molossus showing a significantly higher percentage, and other times, E. glaucinus. In both species, the principal cell was the most abundant (> 77%), followed by basal cells at approximately 13% and apical cells at 4% in all segments. Spermatozoa were observed in greater amounts in corpus and cauda epididymis segments
Resumo
The ability of certain species of bats to store viable spermatozoa in the cauda epididymis, for periods of many months beyond the end of spermatogenesis was first recognized over a century ago. However, information about the bat epididymis is still scarce or absent. Thus, this study aimed to characterize and to compare morphologically and morphometrically the regional histology of the epididymis of Eumops glaucinus and Molossus molossus (Chiroptera: Molossidae). Histologically, the epididymis of both species was subdivided into 4 segments: initial segment, caput, corpus and cauda. In comparing the two species, it was observed that the tubular and luminal diameters and percentage of interstitial tissue showed significant differences in all segments. The epithelial height, in both, is greater in the initial segment with a decrease until the cauda epididymis. In relation to the luminal diameter, both species showed a gradual increase from the initial segment to the cauda. The percentage of epithelium, lumen and interstitial tissue varied between both, sometimes M. molossus showing a significantly higher percentage, and other times, E. glaucinus. In both species, the principal cell was the most abundant (> 77%), followed by basal cells at approximately 13% and apical cells at 4% in all segments. Spermatozoa were observed in greater amounts in corpus and cauda epididymis segments