RESUMO
Sitophilus zeamais is one of the most aggressive pests of stored grains, causing a significant decrease in the nutritional quality of the grains and major losses in economic trade. The foraging capacity of this pest is assigned to its highly efficient digestive system. Investigations on the morphofunctional features of the midgut, which is the most active region of the alimentary canal, are fundamental to understand the feeding habits of this species. In this study, the midgut of adult insects was isolated, processed, and analyzed on light microscopy, scanning and transmission electron microscopy, protein and enzymatic activities determination, including analyses of the starch hydrolysis products. In S. zeamais, the midgut was differentiated into anterior midgut and posterior midgut, and consisted of digestive, regenerative and endocrine cells. The anterior midgut showed high density of regenerative crypts. Cells containing organelles associated with protein synthesis and presence of amylases and lipases indicated that majority of the digestion process occurred in the anterior midgut. The posterior midgut exhibited numerous gastric caeca and peritrophic membrane. Cells with poorly differentiated cytoplasmic into organelles, elongated microvilli, and low enzymatic activities indicated that the posterior midgut was mainly involved in absorption.
Assuntos
Gorgulhos/anatomia & histologia , Gorgulhos/fisiologia , Animais , Enzimas/análise , Intestinos/anatomia & histologia , Intestinos/citologia , Intestinos/enzimologia , Intestinos/fisiologia , Microscopia , Amido/metabolismo , Gorgulhos/citologia , Gorgulhos/enzimologiaRESUMO
The present research describes the histology of the midgut, gastric caeca, and pyloric valve of Tropidacris collaris (Stoll, 1813), (Orthopetera: Romaleidae). We used light microscopy, staining (Gomori's trichrome and periodic acid-Schiff (PAS)), and a routine histological analysis method (hematoxilin-eosin). The insects were obtained from, and also bred in, the Laboratory of Entomology, Department of Biology, of the Rural Federal University of Pernambuco (UFRPE). The collected material was fixed in alcoholic Boüin and embedded in paraplast. The results demonstrated that the midgut wall is composed of an inner epithelial layer and two outer layers of striate muscles: one internal (circular) and the other external (longitudinal), with connective tissue between the muscle fibers. The epithelium is single-layered, with two cell types: regenerative and elongated columnar. The gastric caeca presents muscle layers similar to those of the midgut. Simple columnar epithelium lines the gastric caeca, which presents villi and projects towards the lumen. The pyloric valve is of striate muscle tissue, covered by a single epithelial-cell layer.
A presente pesquisa teve como objetivo descrever a histologia do mesêntero, cecos gástricos e válvula pilórica de Tropidacris collaris (Stoll, 1813) (Orthoptera: Romaleidae), por meio da microscopia de luz, utilizando-se colorações especiais (Tricrômico de Gomori e P.A.S. - Ácido periódico de Schiff) e de rotina (Hematoxilina-Eosina). Os insetos foram obtidos da criação existente no Laboratório de Entomologia, do Departamento de Biologia, da UFRPE. O material coletado foi fixado em Boüin alcoólico e processado para inclusão em "paralast". Os resultados mostraram que a parede do mesêntero é constituída por duas camadas de músculo estriado: uma interna (circular) e outra externa (longitudinal), com a presença de tecido conjuntivo entre as fibras musculares. O epitélio é do tipo simples, constituído por dois tipos de células: células regenerativas e células colunares altas. Os cecos gástricos também apresentam as camadas de músculo semelhantes às observadas no mesêntero. O tecido epitelial é do tipo simples colunar projetando-se para a luz do órgão, formando vilosidades. A válvula pilórica é constituída por tecido muscular estriado, recoberto por tecido epitelial.