Ultrastructural aspects of spermatogenesis in Phalloceros caudimaculatus (Teleostei, Poeciliidae) / Aspectos ultraestructurales de la espermatogénesis en Phalloceros caudimaculatus (Teleostei, Poeciliidae)

The aim of the present study was to analyze the ultrastructural aspects of spermatogenesis in Phalloceros caudimaculatus, during cell proliferation. The parenchyma is organized morphologically as lobular restricted spermatogonial testis. Spermiogenesis in this species is characterized by four morphological stages of development (spermatids S1 through S4). The mature spermatids and spermatozoa heads are situated at the periphery of the cyst surrounded by the cytoplasm of the Sertoli cells. The germ cell's ultrastructure and spermatogenesis in P. caudimaculatus are very similar to that of other poeciliids.

El objetivo del presente estudio fue analizar los aspectos ultraestructurales de la espermatogénesis en Phalloceros caudimaculatus, durante el periodo de proliferación celular. El parénquima testicular está morfológicamente organizado como lobular espermatogonial restricto. La espermiogénesis en esta especie se caracteriza por cuatro etapas morfológicas de desarrollo (espermátidas S1 hasta S4). Las cabezas de las espermátidas maduras y espermatozoides están situadas en la periferia de los cistos, rodeados por el citoplasma de las células de Sertoli. La ultraestructura de las células germinativas y la espermatogénesis en P. caudimaculatus son muy similares a las de otros poecílideos.

An ultrastructural study of spermiogenesis in two species of Sitophilus (Coleoptera: Curculionidae)

The spermiogenesis of Sitophilus zeamais and Sitophilus oryzae, the maize and the rice weevil, respectively, was studied by light microscopy and scanning and transmission electron microscopy. Sitophilus spp. is the most widespread and destructive primary pest of stored cereals in the world. The spermiogenesis occurs within cysts. There are approximately 256 germ line cells per cyst. Inside each cysts, all the spermatids are in the same stage of maturation. The ultrastructure of the spermatozoa of S. zeamais and S. oryzae is similar to that described for other beetles. The head is formed by a three-layered acrosome with the perforatorium, the acrosomal vesicle, the extra-acrosomal layer and the nucleus. The flagellum has the typical axoneme formed by a 9+9+2 microtubules arrangement, two mitochondrial derivatives and two accessory bodies. The typical pattern for Curculionidae spermatozoa described here may provide useful information for future phylogenetic analysis of the superfamily Curculionoidea.

Protein detection in spermatids and spermatozoa of the butterfly Euptoieta hegesia (Lepidoptera)

This study was undertaken to detect protein components in both sperm types of the butterfly Euptoieta hegesia. These spermatozoa possess complex extracellular structures for which the composition and functional significance are still unclear. In the apyrene sperm head, the proteic cap presented an external ring and an internal dense content; basic proteins were detected only in external portions. In the tail, the paracrystalline core of mitochondrial derivatives and the axoneme are rich in proteins. The extratesticular spermatozoa are covered by a proteic coat, which presented two distinct layers. In eupyrene spermatozoa, acrosome and nucleus were negatively stained, probably because of their high compaction. In the tail, there is no paracrystalline core and the axoneme presented a very specific reaction for basic proteins. The lacinate and reticular appendages are composed of cylindrical sub-units and presented a light reaction to E-PTA and a strong reaction to tannic acid. A complex proteic coat also covers the extratesticular spermatozoa. We found similarities between both extratesticular coats, indicating a possible common origin. Both spermatozoon types are rich in proteins, especially the eupyrene appendages and the extratesticular coats. We believe that both coats are related to the sperm maturation and capacitation processes.

Morphological study of the spermatogenesis in the teleost Piaractus mesopotamicus

The spermatogenesis of Piaractus mesopotamicus was investigated under light and transmission electron microscopy. The specimens were captured from their natural environment (Rio Miranda and Rio Aquidauana, Pantanal Matogrossense, Brazil) during April and September. The results were compared with the spermatogenic data of specimens under captivity condition. In both conditions, P. mesopotamicus presented the typical spermatogenesis pattern of the teleost fishes, showing no significative differences. The spermatozoon was classified as type I, which has a globular head without acrosome, a short middle piece and a long tail constituted only by the flagellum. This type of spermatozoon is considered the basic type in fishes.

Ultrastructure of spermatogenesis and sperm development in Saccocoelioides godoyi Kohn & Froes, 1986 (Digenea, Haploporidae)

Ultrastructural observations of spermatogenesis and sperm development of Saccocoelioides godoyi, an intestinal parasite of Leporinus friderici (Bloch, 1794) are described. The irregular-shaped spermatogonia form a peripheral layer, and show a prominent nucleus. Spermatocytes are larger than spermatogonia, and in the early stage present synaptonemal complex. Spermatids show nuclei smaller than the spermatocytes. Spermiogenesis is characterized by outgrowth of the zone of differentiation, presenting basal bodies, separated by an intercentriolar body. At the end of this process, the spermatozoa are released into the residual cytoplasmic mass. The spermatozoa of S. godoyi are elongate, similar to the pattern described for other Digenea, showing nuclei, mitochondria and two axonemes with the 9+1 configuration. The peripheral cortical microtubules on the dorsal and ventral faces are laterally interrupted

Assessment of the degree of contamination of rat germ cell preparations using specific cDNA probes

Recent reports showing a decrease in sperm count in men have brought new concerns about male infertility. Animal models have been widely used to provide some relevant information about the human male gamete, and extrapolations are made to men and to the clinical context. The present study assesses one of the methods us for separation of germ cells of the adult rat testis, namely centrifugal elutriation followed by density gradients (Percoll(). This method was chosen since it presents the best results for cell purity in separating germ cells from the rat testis. A comparison between continuous and discontinuous Percoll( gradients was performed in order to identify the best type of gradient to separate the cells. Maximal cell purity was obtained for spermatocytes (81 ñ 8.2 per cent, mean ñ SEM) and spermatids (84 ñ 2.6 per cent) using centrifugal elutriation followed by continuous Percoll( gradients. A significant difference in purity was observed between elongating spermatids harvested from continuous Percoll( gradients and from discontinuous gradients. Molecular analysis was used to assess cell contamination by employing specific probes, namely transition protein 2 (TP2), mitochondrial cytochrome C oxidase II (COX II), and sulfated glycoprotein 1 (SGP1). Molecular analysis of the samples demonstrated that morphological criteria are efficient in characterizing the main composition of the cell suspension, but are not reliable for identifying minimal contamination from other cells. Reliable cell purity data should be established using molecular analysis.

Adhesion structures between spermatids of Myogrillus sp (Orthoptera)

As células germinativas de Myogrillus sp, em um mesmo cisto, säo interconectadas por pontes intercelulares que ainda estäo presentes no início da espermiogênese. Nessa fase as células comprimidas no cisto, tomam forma poligonal e nas faces justapostas desenvolvem-se complexos juncionais do tipo desmosoma septado. Com a eliminaçäo de parte do citoplasma os espaços intercelulares se alargam e as conexöes se desfazem para reaparecerem entre parte das espermátides tardias, a partir de pequenas pontuaçöes ligadas a membrana celular. As pontuaçöes se organizam regularmente, tomando novamente a forma de desmosomas septados. Sugere-se que a funçäo destas junçöes seja manter as células juntas, de maneira organizada, depois que as pontes intercelulares säo desfeitas

Células multinucleadas nos túbulos seminíferos de rato albino / Multinucleate cells in the seminiferous tubules of the albino rat

Foram efetuados estudos citológicos das formaçöes multinucleadas de espermátides, aos microscópios óptico e eletrônico, em testículos de ratos albinos da linhagem Wistar, submetidos a fonte externa de calor por período de tempo pré-determinado. As formaçöes multinucleadas apresentam organizaçöes peculiares tanto do núcleo como do citoplasma e alteraçöes dos acrossomas. A presença dessas formaçöes ocorre em situaçöes em que se observa degeneraçäo das células do epitélio seminífero. Contudo, no compartimento adluminar dos túbulos seminíferos as formaçöes multinucleadas acabam degenerando. Elas resultam da confluência das membranas citoplasmáticas das espermátides em fase acrossômica e de capuz cefálico, por defeitos nas pontes intercelulares que as conectam, o que leva ao aparecimento de verdadeiros "clones celulares"

Detection of cholesterol by digitonin in coated membranes of the Golgi complex in the guinea pig spermatid

En la face de maduración o condensación del complejo de Golgi de la espermátide de cobayo, se presentan las membranas de las cisternas densas y de las vesículas de condensación con características especiales que las diferencian del resto de las membranas del Golgi. Las membranas de la fase de condensación son más gruesas, están en su mayor parte cubiertas por una trama poligonal del tipo característico de la clathrina y tratadas con la técnica de la digitonina forman los típicos rulos y agujas del complejo digitonina-colesterol. Esta observación revela que ambos componentes - clathrina y colesterol - pueden coincidir en la misma membrana, se concentran en la cara interna del Golgi y por fusión de membranas se transfieren a la membrana externa del acrosoma