黑缘烟蟋螽丝腺结构

Fine structure of silk glands of Capnogryllacris nigromarginata(Orthoptera:Gryllacrididae)

【目的】蟋螽是直翅目中唯一具有吐丝筑巢行为的类群。本研究旨在探讨蟋螽丝腺的结构特点。【方法】应用解剖学观察、免疫荧光、苏木精-伊红染色、PAS苏木精染色、扫描电镜和透射电镜等方法从细胞水平对黑缘烟蟋螽Capnogryllacris nigromarginata丝腺的显微与超微结构进行了观察。【结果】黑缘烟蟋螽丝腺由导管和腺泡构成。腺泡由鞘细胞延伸形成的结缔组织鞘包围。腺泡的主体有4种细胞,分别为Ⅰ型分泌细胞、Ⅱ型分泌细胞、围细胞和腔细胞。Ⅰ型和Ⅱ型分泌细胞为大的腺细胞,形状不规则。分泌细胞细胞核很大,胞质内有大量的内质网和分泌颗粒。Ⅰ型分泌细胞靠近腺泡中心,PAS-苏木精染色表明Ⅰ型分泌细胞内含糖蛋白,Ⅱ型分泌细胞在腺泡外周,位于Ⅰ型分泌细胞与围细胞或结缔组织鞘之间。腔细胞分散在分泌细胞之间,包围形成胞外运输分泌物的通道。围细胞与鞘细胞接触,具有由细胞膜内陷形成的微绒毛腔,胞质内有大量的线粒体。围细胞微绒毛腔与腔细胞包围的细胞外运输通道相连,分泌细胞分泌的颗粒聚集在分泌细胞和胞外运输通道之间的连接处,并将分泌物排出至胞外运输通道。多个腺泡的胞外运输通道汇集到由单层细胞组成的丝腺导管。单层导管细胞靠近管腔外围具有规则排列的质膜内陷和大量伸长的线粒体;靠近管腔的一侧具连续的细胞膜突起,在导管壁的表皮下紧密排列。【结论】黑缘烟蟋螽丝腺分泌细胞分为Ⅰ型分泌细胞和Ⅱ型分泌细胞。分泌物质产生及分泌过程依次经过分泌细胞、腔细胞包围的胞外通道、分支导管、总导管和唾窦。其中在腺泡细胞之间,分泌物向外运输过程中,围细胞微绒毛腔的微丝束可能对分泌物的外排提供推动力。

【Aim】Raspy crickets(Orthoptera:Gryllacrididae)are a unique group in the Orthoptera,and they produce silk and use it to build shelters.The purpose of this study is to investigate the structural characteristics of their silk glands.【Methods】The fine structure and ultrastucture of silk glands of Capnogryllacris nigromarginata were observed by anatomy observation,immunofluorescence,hematoxylin-eosin staining,PAS-hematoxylin staining,scanning electron microscopy(SEM)and transmission electron microscopy(TEM).【Results】The silk glands of C.nigromarginata are composed of acini and silk ducts.Each acinus is composed of a fibrous sheath enclosing four main types of cells:typeⅠsecretory cells,typeⅡsecretory cells,peripheral cells and canal cells.TypeⅠandⅡsecretory cells are large glandular cells in irregular shape.The secretory cells have large nuclei.The cytoplasm of secretory cells is characterized by containing abundant endoplasmic reticulum and secretory particles.TypeⅠsecretory cells are near the center of acinus.PAS-hematoxylin staining showed that typeⅠsecretory cells contain glycoprotein.TypeⅡsecretory cells are at the peripheral region of acinus located between typeⅠsecretory cells and peripheral cells or sheath cells.The canal cells are scattered between the secretory cells and form the extracellular transport canal of secretion.In contact with the sheath cells,peripheral cells have microvilli cavity formed by cell membrane invagination,and there are a large number of mitochondria in the cytoplasm.The microvilli cavity is connected to an extracellular canal surrounded by canal cells.Secretory particles are accumulated at the junction of the secretory cells and the extracellular transport canal.Then they discharge secretions to the extracellular transport canals.The extracellular canals of multiple acini converge to the silk duct composed of a single layer of cells.The cell periphery of the silk duct is involved in the organization of a series of deep invaginations of the plasma membrane.A large number of elongated mitochondria can be observed around the cell plasma membrane invaginations.The apical border of the silk duct cell near the inner lumen has continuous membrane processes that are closely aligned under the cuticle of the duct wall.【Conclusion】The secretory cells of silk glands of C.nigromarginata can be divided into typeⅠand typeⅡsecretory cells.The production and secretion process of secretory materials in turn pass through secretory cells,extracellular canals of canal cells,branch ducts,common duct of silk glands,and salivarium.When the secretions are transported outward from the extracellular canal surrounded by the canal cells,the microfilaments in the microvilli cavity of peripheral cells may provide impetus for the excretion of secretions.