title: Quantification of endocrine cells and ultrastructural study of insulin granules in the large intestine of opossum Didelphis aurita (Wied-Neuwied, 1826).
abstract: This study aimed to investigate the distribution of argyrophil, argentaffin, and insulin-immunoreactive endocrine cells in the large intestine of opossums (Didelphis aurita) and to describe the ultrastructure of the secretory granules of insulin-immunoreactive endocrine cells. Fragments of the large intestine of 10 male specimens of D. aurita were collected, processed, and subjected to staining, immunohistochemistry, and transmission electron microscopy. The argyrophil, the argentaffin, and the insulin-immunoreactive endocrine cells were sparsely distributed in the intestinal glands of the mucous layer, among other cell types of the epithelium in all regions studied. Proportionally, the argyrophil, the argentaffin, and the insulin-immunoreactive endocrine cells represented 62.75%, 36.26%, and 0.99% of the total determined endocrine cells of the large intestine, respectively. Quantitatively, there was no difference between the argyrophil and the argentaffin endocrine cells, whereas insulin-immunoreactive endocrine cells were less numerous. The insulin-immunoreactive endocrine cells were elongated or pyramidal, with rounded nuclei of irregularly contoured, and large amounts of secretory granules distributed throughout the cytoplasm. The granules have different sizes and electron densities and are classified as immature and mature, with the mature granules in predominant form in the overall granular population. In general, the granule is shown with an external electron-lucent halo and electron-dense core. The ultrastructure pattern in the granules of the insulin-immunoreactive endocrine cells was similar to that of the B cells of pancreatic islets in rats.
authors.affiliation: Department of General Biology, Federal University of Viçosa (UFV), Avenida Peter Henry Rolfs, s/n. Campus Universitário, Viçosa 36570-000, MG, Brazil. Electronic address: daiane.santos@ufv.br.
authors.forename: Daiane Cristina Marques
authors.initials: DC
authors.lastname: dos Santos
authors.affiliation: Department of General Biology, Federal University of Viçosa (UFV), Avenida Peter Henry Rolfs, s/n. Campus Universitário, Viçosa 36570-000, MG, Brazil.
authors.forename: Marli do Carmo
authors.initials: Mdo C
authors.lastname: Cupertino
authors.affiliation: Department of General Biology, Federal University of Viçosa (UFV), Avenida Peter Henry Rolfs, s/n. Campus Universitário, Viçosa 36570-000, MG, Brazil.
authors.forename: Maria do Carmo Queiroz
authors.initials: Mdo C
authors.lastname: Fialho
authors.affiliation: Laboratory of Digestive and Neuroendocrine Pathology, Federal University of Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
authors.forename: Alfredo Jose Afonso
authors.initials: AJ
authors.lastname: Barbosa
authors.affiliation: Department of Veterinary Medicine, Federal University of Viçosa (UFV), Viçosa, MG, Brazil.
authors.forename: Cláudio Cesar
authors.initials: CC
authors.lastname: Fonseca
authors.affiliation: Department of Animal Biology, Federal University of Viçosa (UFV), Viçosa, MG, Brazil.
authors.forename: Sirlene Souza Rodrigues
authors.initials: SS
authors.lastname: Sartori
authors.affiliation: Department of General Biology, Federal University of Viçosa (UFV), Avenida Peter Henry Rolfs, s/n. Campus Universitário, Viçosa 36570-000, MG, Brazil.
authors.forename: Sérgio Luis Pinto
authors.initials: SL
authors.lastname: da Matta
mesh_terms: D000818:Animals; D003594:Cytoplasmic Granules / Q000648:ultrastructure*; D055098:Endocrine Cells / Q000378:metabolism / Q000648:ultrastructure*; D004759:Enterochromaffin Cells / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D007328:Insulin / Q000378:metabolism*; D007420:Intestine, Large / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009893:Opossums / Q000378:metabolism*; D051381:Rats
chemical_list: D007328:Insulin
keywords: Argentaffin endocrine cells; Argyrophil endocrine cells; Histochemistry; Immunohistochemistry; Insulin-immunoreactive endocrine cells; Transmission electron microscopy