庭疾灶螽中肠及马氏管结构

Structures of the midgut and Malpighian tubules in the cave cricket,Tachycines asynamorus(Orthoptera:Rhaphidophoridae)

【目的】本研究旨在以庭疾灶螽Tachycines asynamorus为例探索驼螽消化系统和排泄系统在结构上与其生活环境的适应关系。【方法】运用解剖学方法、石蜡切片技术、冰冻切片技术及超薄切片技术对庭疾灶螽中肠及马氏管的结构进行研究。【结果】庭疾灶螽中肠向前延伸出3个胃盲囊包围着前胃。中肠上皮由再生细胞、柱状上皮细胞和内分泌细胞构成,具有典型的再生细胞龛;闭合型内分泌细胞紧贴在再生细胞龛的外围,基底区聚集大量的分泌颗粒。柱状上皮细胞内聚集有2类大的分泌颗粒:线团状颗粒和电子密度很高的球状颗粒;中肠管腔内有明显的围食膜结构,中肠基底部由基膜和肌肉层组成。马氏管着生在中后肠的交界处,从横切面看马氏管管壁具有3~5个细胞,细胞近管腔端部具有大量长微绒毛,细胞质内分布着电子致密的同心圆球晶体,基底膜内折形成膜迷路。【结论】庭疾灶螽中肠柱状上皮细胞的线团状颗粒由微丝包裹;内分泌细胞由再生细胞龛中的细胞分化而来,产生内分泌颗粒并将其排到血腔;中肠基膜发达,包含微丝与复合糖成分,基膜通过对中肠上皮细胞的支撑作用为肠道蠕动提供保障。庭疾灶螽马氏管细胞中可见大量颗粒和大量同心圆球晶体,推测可能是一种储存排泄。

【Aim】Taking the cave cricket,Tachycines asynamorus,as an example,this study aims to explore the structural adaptation relationship of digestive system and excretory system of cave crickets to living environment.【Methods】The structures of midgut and Malpighian tubules of T.asynamorus were explored by anatomical methods,paraffin section,frozen section and ultrathin section.【Results】Three gastric caeca of midgut of T.asynamorus extend forward to enclose a proventriculus.The midgut epithelia consist of regenerative cells,columnar cells,and endocrine cells,with typical niches of regenerative cells.Closed endocrine cells are usually located in the periphery of the niches and a large number of secretory granules are gathered in the basal region of endocrine cells.There are two kinds of large secretory granules in columnar cells,linear clump-like ones and spherical ones with high electron density.In the lumen of the midgut,there is a distinct peritrophic matrix.The base of the midgut is composed by the basal lamina and muscle layer.Malpighian tubules are joined to the digestive tract at the junction of the midgut and the hindgut.The transverse section of the Malpighian tubules contains 3-5 cells.There are a vast number of long microvilli in the apical side of the cells,facing the lumen.Numerous concentrically layered spherites with dense electrons were observed in the cells.In the basal regions of the epithelial cells,there are numerous basement membranes which form membrane labyrinth by infolding.【Conclusion】In the midgut of T.asynamorus,the linear clump-like secretory granules in columnar cells are wrapped by microfilaments.The endocrine cells from the niche stem cell produce endocrine granules,and then excrete the endocrine granules into the hemocoel.The midgut basal lamina including glycoconjugates and microfilaments develops well and provides support for intestinal peristalsis by supporting midgut epithelial cells.A large number of particles and concentrically layered spherites exist in the Malpighian tubule cells of T.asynamorus,implying their functions of storage and excretion.