Additional Ultrastructural Observations of the First Segments of Malpighian Tubules in Cenocorixa bifida (Hemiptera: Corixidae) in Relation to Reabsorption of Solutes
Additional Ultrastructural Observations of the First Segments of Malpighian Tubules in Cenocorixa bifida (Hemiptera: Corixidae) in Relation to Reabsorption of Solutes
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DOI：
10.1603/an10055
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发表时间：
2011-07-01
影响因子：
2.3
通讯作者：
Kelly-Worden, Marie
中科院分区：
文献类型：
--
作者：
Jarial, Mohinder S.;Kelly-Worden, Marie
本文描述了双裂空盲蝽（Cenocorixa bifida亨格福德）马氏管第一节的超微结构。四个小管的第一段向近端排空进入中肠-后肠连接处。其鳞状上皮由含有两种类型线粒体的单核细胞组成。细胞位于一个突出的基膜上，具有短，浅，宽间距的基底质膜内折叠，与大线粒体和一些短钝微绒毛密切相关，缺乏线粒体突出到管腔中。与此形成鲜明对比的是，功能分泌的第四节细胞，显示出许多长的基底膜内折，深入细胞质和许多长的微绒毛在管腔边缘。第一节细胞的细胞质含有致密体、小线粒体、微管、小泡和空泡，并富含滑面内质网，产生透明的空泡，但粗面内质网和高尔基体稀少。顶端质膜被糖萼覆盖，并显示出被膜小凹，夹断被膜小泡。顶端的细胞质中有许多小泡，包括细颗粒物质、光滑小泡、致密小管、大空泡、初级溶酶体和多泡体。侧质膜由广泛的连接复合体连接，每个复合体由顶端平滑分隔连接、插入间隙连接和基底异细胞梯状连接组成。第一节和第四节细胞超微结构特征的对比表明，第一节参与重吸收而不是分泌无机和有机溶质。
The ultrastructure of the first segment of the four-segmented Malpighian tubules of Cenocorixa bifida Hungerford (Hemiptera: Corixidae) is described. The first segment of each of the four tubules empties proximally into the midgut-hindgut junction. Its squamous epithelium is composed of a single layer of binucleated cells containing two types of mitochondria. The cells rest on a prominent basal lamina and possess short, shallow, widely spaced basal plasma membrane infoldings closely associated with large mitochondria and a few short blunt microvilli devoid of mitochondria projecting into the lumen. In sharp contrast, the fourth segment cells that are secretory in function, display numerous, long basal membrane infoldings that penetrate deeply into the cytoplasm and numerous long microvilli at the luminal border. The cytoplasm of the first segment cells contains dense bodies, small mitochondria, microtubules, vesicles, and vacuoles and is rich in smooth endoplasmic reticulum, giving rise to clear vacuoles, but rough endoplasmic reticula and Golgi apparati are sparse. The apical plasma membrane is covered with glycocalyx and displays coated pits pinching off coated vesicles. The apical cytoplasm displays numerous vesicles containing fine granular material, smooth vesicles, dense tubules, large vacuoles, primary lysosomes, and multivesicular bodies. The lateral plasma membranes are linked by extensive junctional complexes each composed of an apical smooth septate junction, intercalated gap junctions, and a basal heterocellular scalariform junction. The contrast in ultrastructural features between of the first segment and fourth segment cells suggests that the first segment is involved in reabsorption than secretion of inorganic and organic solutes.