Aspectos da morfologia do intestino grosso do gambá Didelphis aurita (Wied-Neuwied, 1826) com ênfase nas células enteroendócrinas

• Autor(a) principal: Santos, Daiane Cristina Marques dos
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/260
• topic: Células endócrinas imunorreativas à insulina; Células endócrinas argirófilas; Células endócrinas argentafins; Intestino grosso; Gambás; Insulin immunoreactive endocrine cells; Argyrophil endocrine cells; Argentaffin endocrine cells; Intestine; Opossum; CNPQ::CIENCIAS BIOLOGICAS::BIOLOGIA GERAL

The digestive system has a crucial role in the control of energy homeostasis and this regulatory mechanism is partly attributed by the enteroendocrine cells. Such cells represent the largest population of hormone-producing cells of the organism of the eutherian mammals and act in the control of secretion, absorption, motility and proliferation of cells in the digestive tract. Because of the importance of those enteroendocrine cells, the objectives of this work was to characterize the morphology, to identify and quantify the argyrophil, argentaffin, and insulin-immunoreactive endocrine cells of the large intestine, in the cecum, colon (ascending, transverse, and descending) and rectum of the Opossums D. aurita. Fragments of the large intestine wall of 10 male opossum D. aurita specimens were collected, processed, and submitted to histochemistry, immunohistochemistry, and scanning transmission electron microscope. The tunics of the large intestine of D. aurita presented morphological characteristics that have already been described for eutherian mammals. The inner circular muscular layer on all portions and regions analyzed is thicker than the external longitudinal layer among the analyzed regions. This layer presented itself thicker in the rectum than in the cecum and ascending colon. The number of mucous secreting cells increased in the region of the cecum towards the rectum. These cells have acid and neutral mucins, indicating that the mucus production is mixed. Proportionately, the argyrophil, argentaffin, and insulin-immunoreactive endocrine cells represent 62.75%, 36.26% and 0.99% of the total determined in endocrine cells of the large intestine, respectively. There was no quantitative difference between argentaffin and argyrophil endocrine cells, while insulin- immunoreactive endocrine cells are less numerous. The argyrophil and argentaffin endocrine cells have elongated, pyramidal or rounded shapes, with an ovoid nucleus and cytoplasm with large amount of secretion granules. Most of these cells is open type and has extension reaching the apical luminal surface. Other cells, without apparent communication with the lumen, of the closed type, are commonly located at the base of the intestinal glands, and have the basal portion usually dilated and greater contact with adjacent cells. The insulin-immunoreactive endocrine cells are elongated or pyramidal with rounded nuclei, irregular contour, and have loads of secretion granules distributed throughout the cytoplasm. The granules have different sizes and electron densities and are classified into immature and mature. The ultrastructural pattern of the granules of the insulin-immunoreactive endocrine cells is similar to that of B cells of pancreatic islets. The mature forms of the granules are predominant and represent 65% of the secretion granules.