922 resultados para skull morphology


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Leafcutter ants of the genus Atta Fabricius are serious agricultural pests. Morphological studies of immature stages within this group are few, and the data provided for species of considerable importance are usually incomplete. In this study, the immatures of Atta sexdens Linnaeus are described and compared using light and scanning electron microscopy. Only specimens from founding stage colonies (i.e., lacking adult workers) were used. The existence of four larval instars was estimated by a frequency plot of maximum head widths, and the larvae of different instars differed from each other mainly by their bodily dimensions. Worker larvae belonged to two distinct morphological castes: (1) gardeners and nurses and (2) within-nest generalists. The worker larvae described in this study differed from a previous description of the same species by the following traits: the existence of a genal lobe, the number of clypeal hairs, the presence of two hairs on the ninth abdominal somite, the presence of hairs on the anterior surface of the labrum, and the shape of the maxillary palpus. This study provides a comparative analysis of immature stages of A. sexdens that may be relevant to future morphological and biological studies of the Attini. Microsc. Res. Tech. 75:10591065, 2012. (c) 2012 Wiley Periodicals, Inc.

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The fat body cells of virgin females and queens of Pachycondyla striata ants belonging to the subfamily Ponerinae are illustrated from morphologic, ultramorphologic and morphometric viewpoints. Camera lucida drawing techniques were used, as well as scanning electronic microscopy (SEM). Measurements of trophocytes and oenocytes areas in the tissue were recorded. The results showed that in P. striata queens and virgin females the trophocytes are arranged in cord-like formations in association with oenocytes. Trophocytes of both castes had round shapes, with rather vacuolized cytoplasm, whereas oenocytes, being smaller than trophocytes, had more homogeneous cytoplasm. It was also observed that both trophocytes and oenocytes of virgin females were larger than those found in the same queen cellular types.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The developmental anatomy and morphology of the ovule and seed in several species of Heliconia were investigated as part of an embryological study of the Heliconiaceae and to provide a better understanding of their relationships with the other families of the Zingiberales. Heliconia species have an ovule primordium with an outer integument of both dermal and subdermal origin. The archesporial cell is divided into a megasporocyte and a single parietal cell, which in turn are divided only anticlinally to form a single parietal layer, disintegrating later during gametogenesis. The embryo sac was fully developed prior to anthesis. In the developing seed, the endosperm was nuclear, with wall formation in the globular stage; a nucellar pad was observed during embryo development, but later became compressed. The ripe fruit contained seeds enveloped by a lignified endocarp that formed the pyrenes, with each pyrene having an operculum at the basal end; the embryo was considered to be differentiated. Most of these characteristics are shared with other Zingiberales, although the derivation of the operculum from the funicle and the formation of the main mechanical layer by the endocarp are unique to the Heliconiaceae.

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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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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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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 relative condition factor (Kn), gonadosomatic index (GSI), selected hematological variables and gill morphology of the fish Astyanax fasciatus were analyzed in two sites (site I was unpolluted and site 2 was polluted with untreated domestic sewage) of a tropical river (Camanducaia river, São Paulo State, Brazil). The relationship between the body mass (M-B) and the standard length (L-S) of A. fasciatus from both sites was M-B = 0.00799 L-S(3.51843). Tyhe Kn values from both the males and females were significantly higher in site 2. The mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were higher in females from site 2. Gill tissue anomalies and gill parasites were rare in fish from both sites; however, the number of chloride cells was significantly higher in fish from site 1. A. fasciatus presents high capacity to live in ion-poor and soft water and is able to compensate for environmental changes caused by untreated domestic sewage discharges. (c) 2004 Elsevier B.V. All rights reserved.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)