913 resultados para ultrastructure-vitellogenesis


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Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The aim of the present study was to characterize biopsied and stripped oocytes from the Brazilian endangered teleost pirapitinga (Brycon nattereri) using histochemical and morphological analyses. Biopsied oocytes had a mean diameter of 2.225 mm (modal diameter: 2.312 mm), complete vitellogenesis and a central or slightly eccentric nucleus. Neutral polysaccharides were detected in the follicular cells, zona radiata and yolk globules, while acidic polysaccharides were detected in the follicular cells and cortical alveoli. Ten out of the 19 females treated with two doses of carp pituitary extract (cPE) released oocytes, which were also analysed. Stripping occurred 292 +/- 39 degree-hours after the second dose of cPE and led to a mean spawning weight of 36.2 g, 10% spawning index, 241 oocytes/g of ova, 8222 oocytes/female and 23 oocytes/g of body weight. Stripped oocytes had a mean diameter of 2.33 mm and a mode at 2.375 mm, were weakly adhesive and coloration ranged from wine to brown. Under scanning electron microscopy, stripped oocytes exhibited a single funnel-shaped micropyle located at the animal pole and a zona radiata that measured 7.7 m in thickness with eight pore canals/m(2). Oocyte morphology in Brycon nattereri is similar to that found in other species of the genus, except for the larger size and weaker adhesiveness. These findings provide essential information for a better understanding of the reproductive biology of B. nattereri and the establishment of conservation measures for this threatened species.

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The morphology of the parotid and submandibular glands in the marten, a carnivore, were studied and analyzed under a transmission electron microscope. The nature of the granules in both glands, as well as in the acini and in the secretory tubules, is rather mucous. The structure of the secretory tubules is very characteristic, especially the striated ones. The myoepithelial cells are close to the acini and tubules and covered by the basement membrane separating them from the connective tissue, which enhances its epithelial origin. The cytoplasm of the basal parts of the acinar and tubular cells is abundant and separates the nucleus from the secretion granules. Although the morphology of the salivary glands of many carnivores is known, those of the parotid gland of the marten present peculiar characteristics, since they produce a rather mucous saliva and the granules, when forming, are far from the base as well as from the apex of the secretory cells. The submandibular gland contains granules of different densities, an aspect that in general resembles that of other animals.

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The surface of the digestive tract of Hemisorubim platyrhynchos was analyzed by scanning electron microscopy. Morphometric studies by transmission electron microscopy were performed to analysis the intestinal microvilli. H. platyrhynchos is a Neotropical carnivorous freshwater catfish featuring a short digestive tract composed of a short esophagus, saccular stomach, and intestine with four regions: anterior, middle, posterior, and rectal. The esophageal surface is constituted by fingerprint-like microridges that anchor the mucosubstances secreted by goblet cells facilitating the passage of food. Goblet cells present the opening to the esophageal lumen, between the microridges. Club cells are in basal epithelium and they do not present the opening to the lumen. The gastric luminal surface shows polygon-shaped epithelial cells which secrete granules by exocytose to protect the gastric surface. The intestinal luminal surface reveals folds that are thicker in the anterior intestine than in the posterior intestine, increasing the absorptive surface area. The intestinal surface presents the microvilli of enterocytes and the opening of goblet cells. The morphometric analysis showed that the microvilli are longer in the anterior intestine, significantly decreasing towards the posterior intestine. The microvilli surface area significantly is greater in the anterior and middle intestine than in the posterior intestine. Numerous openings of goblet cells were observed in the posterior intestine acting in epithelial protection and lubrication. SCANNING 9999:1-8, 2015. © 2015 Wiley Periodicals, Inc.

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The interface between stages of Eimeria funduli and hepatocytes of the experimentally infected killifish Fundulus similis was studied ultrastructurally. Parasitophorous vacuoles (PV's) in which meronts, macrogamonts, and microgamonts developed were lined by an inner, smooth membrane and an outer, ribosome-studded membrane. The outer membrane bordered on the cytoplasm of the host cell, whereas the inner one limited the PV. The origins of these membranes have not been determined with certainty, but images were observed in which both membranes appeared to be continuous with the outer nuclear membrane of the host cell. Furthermore, the outer PV membrane was continuous with membranes of rough endoplasmic reticulum in the host cell. For stages which were rapidly growing or differentiating, the inner membrane blebbed into the PV. Blebbing ceased and ribosomes detached from the outer membrane after maturation of the meront or fertilization of the macrogamont. Blebbing appears to be a mechanism by which nutrients transfer from the host to the parasite. During sporogony, the inner PV membrane acquired a thin layer of electron dense material, but otherwise membranes lining the PV remained intact. The two PV membranes, probably together with dense material of parasitic origin lining the inner membrane, appear to serve as the oocyst wall enclosing the sporocysts until they are released in the intermediate host.