882 resultados para lipid droplets


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In order to examine the effects of alcohol on the hard palatine mucosa of rats, sixty adult female rats (Rattus norvegicus albinus) were divided into two experimental groups. The control group received solid diet (Purina rat chow) and tap water ad libitum. The alcoholic group received the same solid diet and was allowed to drink only sugar cane brandy dissolved in 30% Gay Lussac (v/v). At the end of periods of 90, 180 and 270 days of treatment, the animals at estro were sacrificed and the hard palatine mucosa were prepared for TEM and SEM methods. The basal cells of the alcoholic groups (90, 180 and 270 days of treatment) demonstrated some alterations: the intercellular spaces between these cells were higher, presented cytoplasmatic lipid droplets and autolysis. Also, the connective tissue showed intense lipid droplets accumulation in the alcoholic groups. These modifications suggested that chronic alcohol ingestion was able to modify the integrity of the cells in the rat hard palatine mucosa.

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Morphological data concerning the venom gland of worker ants of Pachycondyla striata revealed that this gland consists of three distinct regions: an external secretory portion, composed by a secretory filament that bifurcates in order to give rise to other two filaments; an internal secretory portion, represented by the convoluted gland; and a storage portion, represented by a sac-shaped reservoir. The ultrastructural analysis showed that the reservoir is enveloped by a simple pavementous epithelium, coated internally with a cuticle. The external secretory portion is composed by cells forming a simple cubic epithelium, in which the apical portion presents numerous microvilli while the basal portion of the cells shows infoldings of the plasma membrane containing numerous mitochondria. The convoluted gland possesses cells of irregular morphology with nuclei containing condensed chromatin, suggesting inactivity. However, these cells are in fact undergoing secretory activity, which is probably added to the final secretion produced by the gland. The cytoplasm of these cells contains several elements distributed therein, such as ribosomes and polyribosomes, lipid droplets, and protein inclusions in the form of crystals, thus Suggestive of protein storage, which would be used by the insect when metabolically required. (c) 2005 Elsevier Ltd. All rights reserved.

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The ultrastructure of the fat body cells (trophocytes) of the last larval instar of Pachycondyla (= Neoponera) villosa is presented. The cytoplasm is restricted to the cell periphery and to the smaller strips among the vacuoles, protein granules, lipid droplets, and around the nucleus. Cytochemically, the presence of basic amino acids in the protein granules and in the nuclei was observed by using the ethanolic phosphotungstic acid technique (EPTA). The lipid droplets stained for unsaturated lipids. This result was further confirmed by gas chromatography and mass spectrometry, where the unsaturated fatty acids were identified as oleic and linoleic acids together with saturated fatty acids such as palmitic and stearic acid. Carbohydrates (glycogen) were also detected in the fat body. The glycogen is present as beta particles distributed among the lipid droplets and sometimes attached to them.

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The present study describes the ultrastructure of meroistic telotrophic ovaries of the sugarcane spittlebug Mahanarva fimbriolata. In this type of ovary, nurse cells, oogonia, and prefollicular tissue are located at the terminal (distal) regions or tropharium of ovarioles. Oocytes in different developmental stages, classified from I to V, are observed in the vitellarium. Stage I oocytes do not exhibit intercellular spaces in the follicular epithelium, suggesting that synthesis and production of yolk during this stage occurs only through endogenous processes. Small yolk granules of different electron densities are present in the cytoplasm. Few lipid droplets are observed. Stage 11 oocytes exhibit small intercellular spaces in the follicular epithelium. More protein as well as lipid yolk granules are observed in the cytoplasm. In stage III oocytes, intercellular spaces in the follicular epithelium are larger than those observed in the previous stage. Electrondense protein granules of various sizes, larger than those observed in stage 11 oocytes predominate in the cytoplasm. Smaller lipid droplets are also present. In stage IV oocytes, the follicular epithelium exhibits large intercellular spaces. Our data clearly indicate that the opening of these spaces in the follicular epithelium of M. fimbriolata oocytes increases as the intake of exogenous proteins intensifies, that is, in stages IV and Voocytes. During these stages, granular yolk becomes viscous due to the lysis of granules. In stage Voocytes, viscous yolk predominates in the cytoplasm. This type of yolk, however, has not been described for other orders of insects. The chorion of M. fimbriolata oocytes consists of an external layer (exochorion) and an internal one (endochorion), which is in direct contact with the oocyte. Numerous small pores that probably facilitate oxygenation of the internal structures inside the eggs are observed in the exochorion. (c) 2006 Elsevier Ltd. All rights reserved.

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The wasps of the genus Polistes have been considered the key to understanding the evolution of social behavior in Hymenoptera. Several studies have shown that the development of organized insect societies was accompanied by the evolution of structures like exocrine glands, which became specialized to perform specific functions. This article investigates the ultrastructural and cytochemical features of the hypopharyngeal glands of Polistes versicolor. These glands have been studied in depth in social bees, where they occur only in nurses and produce the royal jelly. Our results revealed that these glands basically did not vary among individuals or between sexes. They are constituted by spherical cells, each with a large nucleus and well-developed rough endoplasmic reticulum. Secretion vesicles are abundant, but lipid droplets were not observed, indicating that these glands may not have a role in pheromone synthesis. Acid phosphatase was detected in lysosomes, and also free in the cytosol, but did not seem to be related with cell death. Thus, our results suggest that the hypopharyngeal glands of P. versicolor may not have a specialized social role, but could produce digestive enzymes.