Anatomy and fine structure of the alimentary canal of the spittlebug Lepyronia coleopterata (L.) (Hemiptera: Cercopoidea)

The alimentary canal of the spittlebug Lepyronia coleopterata (L.) differentiates into esophagus, filter chamber, midgut (conical segment, tubular midgut), and hindgut (ileum, rectum). The filter chamber is composed of the anterior extremity of the midgut, posterior extremity of the midgut, proximal Malpighian tubules, and proximal ileum; it is externally enveloped by a thin cellular sheath and thick muscle layers. The sac-like anterior extremity of the midgut is coiled around by the posterior extremity of the midgut and proximal Malpighian tubules. The tubular midgut is subdivided into an anterior tubular midgut, mid-midgut, posterior tubular midgut, and distal tubular midgut. Four Malpighian tubules run alongside the ileum, and each terminates in a rod closely attached to the rectum. Ultrastructurally, the esophagus is lined with a cuticle and enveloped by circular muscles; its cytoplasm contains virus-like fine granules of high electron-density. The anterior extremity of the midgut consists of two cellular types: (1) thin epithelia with well-developed and regularly arranged microvilli, and (2) large cuboidal cells with short and sparse microvilli. Cells of the posterior extremity of the midgut have regularly arranged microvilli and shallow basal infoldings devoid of mitochondria. Cells of the proximal Malpighian tubule possess concentric granules of different electron-density. The internal proximal ileum lined with a cuticle facing the lumen and contains secretory vesicles in its cytoplasm. Dense and long microvilli at the apical border of the conical segment cells are coated with abundant electron-dense fine granules. Cells of the anterior tubular midgut contain spherical secretory granules, oval secretory vesicles of different size, and autophagic vacuoles. Ferritin-like granules exist in the mid-midgut cells. The posterior tubular midgut consists of two cellular types: 1) cells with shallow and bulb-shaped basal infoldings containing numerous mitochondria, homocentric secretory granules, and fine electron-dense granules, and 2) cells with well-developed basal infoldings and regularly-arranged apical microvilli containing vesicles filled with fine granular materials. Cells of the distal tubular midgut are similar to those of the conical segment, but lack electron-dense fine granules coating the microvilli apex. Filamentous materials coat the microvilli of the conical segment, anterior and posterior extremities of the midgut, which are possibly the perimicrovillar membrane closely related to the nutrient absorption. The lumen of the hindgut is lined with a cuticle, beneath which are cells with poorly-developed infoldings possessing numerous mitochondria. Single-membraned or double-membraned microorganisms exist in the anterior and posterior extremities of the midgut, proximal Malpighian tubule and ileum; these are probably symbiotic.     

Morphology and ultrastructure of the alimentary canal of the cicada Platypleura kaempferi (Hemiptera: Cicadidae)

The alimentary canal of cicada Platypleura kaempferi is described. It comprises the oesophagus, filter chamber, external midgut section and hindgut. The elongate oesophagus expands posteriorly, with its posterior end constricting to become a bulb. The filter chamber consists of two parts: a very thin sheath and a filter organ. The filter organ is composed of the anterior and posterior ends of the midgut (internal midgut section), and the internal proximal ends of the Malpighian tubules. The external midgut section differentiates into a collapsed sac and a midgut loop. The latter is divided into three distinct segments. The hindgut contains a dilated rectum and a long narrow ileum. The distal portions of the four Malpighian tubules are enclosed in a peritoneal sheath together with the distal ileum before reaching to the rectum. Ultrastructurally, the oesophagus and the hindgut are lined with a cuticle. The filter chamber sheath consists of cells with large irregular nuclei. Filamentous substances coat the microvilli of the cells of the internal midgut section. The posterior end of the midgut comprises two types of cells, with the first type of cells containing many vesicles and scattered elements of rough endoplasmic reticulum. The anterior and posterior segments of the midgut loop cells have ferritin‐like granules. The ileum cells have well‐developed apical leaflets associated with mitochondria. Accumulations of virus‐like particles enclosed in the membrane are observed in the esophagus, conical segment, mid‐ and posterior segments of the midgut loop.     

Development of the Malpighian tubules in Cloeon dipterum (Ephemeroptera)

The development of the Malpighian tubules is studied in Cloeon dipterum through all stages from the youngest larva to the adult. The Malpighian tubules are found to be outgrowths of the posterior part of the endodermal midgut and not of the ectodermal hindgut. In the adult the part of the intestine with the tubule openings becomes separated by an ingrowing fold of the epithelium from the anterior main part of the midgut that forms a large thin-walled and air-filled bladder. The characteristics of the developmental stages, which served to determine the age of the animals, are given.     

Expression patterns of genes encoding proteins with peritrophin A domains and protein localization in Mamestra configurata

Genes encoding three proteins (McPPAD1-3) with peritrophin A chitin-binding domains (PADs) were identified from a Mamestra configurata larval midgut cDNA library. In addition to midgut, McPPAD1-3 and a previously identified gene encoding the peritrophin, McPM1, were expressed in foregut, hindgut, Malpighian tubules, tracheae, fat body and cuticle; however, the corresponding McPPAD proteins exhibited different localization patterns. McPPAD1 was restricted to the digestive tract and Malpighian tubules, McPPAD2 to Malpighian tubules, and McPPAD3 to the foregut, midgut, hindgut, tracheae and cuticle. Protein fold recognition analysis using tachycitin as a guide structure modelled the McPPAD1 PADs, but not McPPAD2 or McPPAD3 PADs. The McPPAD1 PADs were predicted to contain three anti-parallel β-sheets and a hevein-like fold that form a chitin-binding pocket containing two hydrophobic R-groups in a sandwich-like orientation.     

Ricerche istochimiche e al micro scopio elettronico sui tubi malpighiani di Dacus oleae Gmel.

Summary The Dacus oleae larva possesses four Malpighian tubules, two anterior and two posterior ones, which in pairs enter into a ureter. Before opening into the gut, at the level of the transition zone between the mid- and hindgut, each ureter is dilated into an ampulla.The anterior tubules are divided into four regions: distal, transition, middle and proximal ones: while in the posterior tubules only middle and proximal segments are detectable. The distribution of the enzyme systems is indicated in Fig. 3, while the ultrastructural organization which is typical of the cells composing the different regions is schematically represented in Fig. 1. According to the ultrastructural and enzymatic findings, and the discussion on this subject in the literature, the authors are led to assume that in the distal segment occurs the segregation of uric acid, urates and calcium salts. In the transition segment, and still more in the intermediate one, an indiscriminate transport of water and solutes occurs from the haemocoel into the lumen of the tubule by pinocytosis. A fraction of the catabolites is precipitated as chromolipoidal pigments. The transition stages between cytosomes and pigment are described. Along with secretory phenomena the resorption of useful substances occurs in the proximal region. A similar function is performed by the ureter. In the ampulla, which is characterized by a conspicuous system of deep tubular infoldings both at the apical and basal surfaces of its cells, a massive water resorption is presumed to occur.     

Fine Structure of the Midgut and Hindgut in Lepidocampa weberi (Insecta,Diplura)

The fine structure of the alimentary canal, especially the midgut and hindgut of Lepidocampa weberi (Diplura: Campodeidae) is described. The general organization of the canal is similar to that of Campodea. The midgut epithelium is composed of columnar apical microvillated cells. Each nucleus contains a single intranuclear crystal. Close to the pyloric region, the posterior midgut cells are devoid of microvilli and intranuclear crystals. There is no special pyloric chamber as in Protura or pyloric cuticular ring as in Collembola but a morphological transformation from midgut to hindgut cells. Eight globular Malpighian papillae, consisting of distal microvillated cells and flat proximal cells, open into the gut lumen via ducts formed by hindgut cells. The structure of the hindgut is complicated and can be divided into three segments. The anterior hindgut cells have an irregular shape and compact cytoplasm. A striking interdigitation between the large bottle-shaped epithelial cells and longitudinal muscle cells occurs in the middle segment of the hindgut. The thick cuticle gives rise to long spikes projecting into the gut lumen. The posterior hindgut cells possess the morphological features for water reabsorption. Some hypotheses are advanced about the function of the different regions of the gut.     

Ultrastructure of the malpighian tubules of Schistocerca gregaria

The ultrastructure of the Malpighian tubules of the adult desert locust, Schistocerca gregaria, is described. Male and female adults possess about 233 tubules, which empty proximally into the midgut-ileal region of the alimentary canal by way of 12 ampullae. The tubules vary from 10 mm to 23 mm in length. About one third of them are directed anteriorly, attaching distally at the caeca, while the remainder are directed posteriorly, attaching to other tubules, the rectum or large tracheal trunks adjacent to the hindgut. The Malpighian tubules from all locations examined consist of three ultrastructurally distinct regions: proximal, middle, and distal, referring to their position relative to the midgut. All cell types possess ultrastructural features characteristic of ion transporting tissue, i.e., elaboration of the basal and apical membranes and a close association of these membranes with mitochondria. The distal and proximal segments are short (1.5-1.7 mm) and heavily tracheated, and each is composed of a single, distinct cell type. The middle region is the longest segment of the Malpighian tubule and is composed of two distinct cell types, primary and secondary. Both cell types are binucleate. The more numerous primary cells have large nuclei, contain laminate concretions in membrane-bound vacuoles, and possess large microvilli that contain mitochondria. The secondary cells are smaller and possess smaller nuclei. The microvilli are reduced and lack mitochondria. Secondary cells do not contain laminate concretions. The possible compartmentalization of ion and fluid transport function based on segmentation in the Malpighian tubules is discussed.     

黄脸油葫芦消化道和马氏管的组织学观察

应用石蜡切片技术对黄脸油葫芦Teleogryllus emma(Ohmachi and Matsumura)成虫消化道和马氏管的显微结构进行观察。消化道由前肠、中肠和后肠3部分组成:前肠由内向外可分为6层:内膜、肠壁细胞层、底膜、纵肌、环肌和围膜;中肠组织结构也分为6层,即由内向外依次为围食膜、肠壁细胞层、底膜、环肌、纵肌和围膜;后肠的组织结构与前肠基本相似,但内膜比前肠的薄,且肌肉的排列较前肠不规则,与中肠的肌肉排列相似,即环肌在内,纵肌在外。消化道各部位的结构差异与功能有密切关系。马氏管管壁由8个左右形状多变并具有显著细胞核的大形的单层上皮细胞组成。     

合哑蝉成虫消化道形态、组织结构及超微结构（英文）

【目的】本研究通过合哑蝉Karenia caelatata成虫消化道的形态学、组织学和超微结构研究,进一步了解蝉科(Cicadidae)代表种类的消化道形态和功能分化。【方法】利用光学显微镜和透射电子显微镜技术,对合哑蝉雄成虫消化道的整体形态以及食道、滤室(中肠前端及后端、马氏管基部、后肠基部)、滤室外中肠(锥形体、中肠环)、后肠(回肠、直肠)的一般形态和超微结构进行了详细观察,同时对滤室的组织结构进行了研究。【结果】结果表明,合哑蝉消化道由食道、滤室、滤室外中肠及后肠组成。食道狭长,被有上表皮和内表皮。中肠前端、中肠后端、马氏管基部以及后肠基部被一肌肉鞘包围形成滤室构造。组成中肠前端和后端的细胞基膜高度内褶,顶端的微绒毛发达。中肠后端分布许多线粒体和高电子密度的分泌颗粒。滤室外的中肠包括膨大的锥形体、中肠环。其中,锥形体由两种细胞组成;中肠环分为前、中、后3个不同的区段。前中肠细胞包含大量的分泌颗粒、线粒体、粗面内质网和溶酶体;中中肠细胞含有分泌颗粒;后中肠细胞包括许多低电子密度的分泌颗粒和滑面内质网。类铁蛋白颗粒零星分布于中肠环的前、中区段。组成锥形体和中肠环前端的细胞顶端微绒毛被丝状物质覆盖。后肠被有一层表皮。食道、中肠环中段、直肠细胞中含有微生物。【结论】本研究获得的合哑蝉消化道形态、组织结构和超微结构方面的信息为其功能分化研究提供了重要信息。同时,相关微生物的发现为进一步探讨共生菌与蝉总科昆虫的协同进化提供了信息。     

Genes controlling posterior gut development in theDrosophila embryo

Our present detailed understanding of the genetic mechanisms controlling segmentation has been made possible, in large part, by comprehensive screens of cuticular morphology that identified genes involved in epidermal patterning. To systematically identify genes involved in internal morphogenesis, specifically development of the gut, we have screened mutant embryos produced by a collection of 53 embryonic lethal mutations affecting embryonic pattern formation or differentiation, and a collection of 161 deficiencies covering, in aggregate, approximately 70% of the genome. Staining with the anti-crumbs antibody was used to characterize the Malpighian tubules and hindgut, as well as other internal organs. The geneshuckebein, tailless andwingless, and two previously undescribed loci at 24C/D and 68D/E, are required to establish the primordia for the posterior midgut and hindgut/Malpighian tubules. A locus in region 30A/C is required for extension of the midgut epithelium to surround the yolk, and region 36E/37F is required for outbudding of the Malpighian tubule primordia. Several deficiencies were identified that uncover loci with specific effects on the morphogenesis (elongation, lumen formation) of the hindgut and Malpighian tubules and on the formation of constrictions in the midgut.     

Growth and differentiation of secondary malpighian tubules in the cockroach,Periplaneta americana

Four differentiated Malpighian tubules (primary tubules) extend from the junction of the midgut and hindgut in newly hatched Periplaneta americana. Secondary tubules begin to develop near the base of the primary tubules before hatching and successive nymphal molts. The newly initiated tubules undergo cell division and extensive elongation through the middle of the following intermolt period. During this time, the cells of the distal, middle, and lower middle tubule regions are surrounded by a cellular sheath, have few cytoplasmic processes extending along their basal surfaces, have a small or nonexistent lumen, and contain extremely dilated cisternae of endoplasmic reticulum. The cellular sheath differentiates into the muscle which coils around the mature tubule. Tubules which begin development toward the end of one intermolt period begin to undergo cytodifferentiation toward the end of the next intermolt period. By the middle of an additional intermolt period, the basal infoldings and microvilli of cells in the distal, middle, and lower middle regions have the conformations typical for those regions in differentiated tubules; granular concretions and stellate cells are present within the middle region of the tubule.     

Electron-microscopic study of the excretory system of hungry females of the tick Hyalomma asiaticum P. Sch. et E. Schl. 2]

In H. asiaticum the cells of the Malpighian tubules and these of the rectal cas have the uniform structure: the apical surface is covered with microvilli, the basal plasmatic membrane forms relatively small invaginations. As to ultrastructural characters, there is no distinct division of the Malpighian tubule into departments. The distal ends of the tubules are not only somewhat enlarged and form the so-called ampulla cells of which are noticeably flattened. The microvilli and basal folds of the plasmatic membrane in this area of the tubule are indistinct. The cells of the ampulla and the neighbouring area of the tubule are characterized by the presence of inclusions with mucopolysaccharide secretion confined by the membrane. The microvilli are most developed on cells of the proximal ends of the Malpighian tubules. Well developed microvilli of the rectal sac form a striated border each containing a microtube inside. The basal invaginations are developed here better than in the cells of the Malpighian tubules.     

黄脸油葫芦与短额负蝗马氏管组织结构比较

采用组织学方法对直翅目剑尾亚目和锥尾亚目的两个物种--黄脸油葫芦Teleogryllus emma和短额负蝗Atractomorpha sinensis成虫的马氏管进行了观察,发现两者在着生位置、方式和细胞结构上存在明显不同.着生位置上,黄脸油葫芦的马氏管着生在后肠前端与后肠后端的交界处,短额负蝗的马氏管着生在中肠与后肠的交界处.着生方式上,黄脸油葫芦的马氏管是通过一根无色透明的公共管与肠道相通的,而短额负蝗的马氏管分为12丛,每一丛直接与肠道相连.细胞结构上,黄脸油葫芦的管壁由8个细胞构成,且集中在管的中央,与管壁有空隙;而短额负蝗的管壁由3～4个细胞组成,分散在管壁外围,有马氏管凸.     

Cryptonephric malpighian tubule system in a dipteran larva,the New Zealand glow-worm, Arachnocampa luminosa (Diptera: Mycetophilidae): A structural study

The Malpighian tubules of the glow-worm are divided into four morphologically distinct regions, each composed of a different cell type. Part 3 of the Malpighian tubules of A. luminosa is intimately bound to the rectum by a layer of fat body. This association of the tubules with the hindgut is referred to as a cryptonephric system. This type of arrangement has been described in some Coleoptera and the larvae of most Lepidoptera but has never before been reported in the Diptera. In the glow-worm the cryptonephric tubules themselves are small, and adjacent to the fat body the epithelial cells are modified to form very thin windows or ‘leptophragmata’ (Lison, 1937). The main epithelial cells exhibit features characteristic of highly active, secretory Malpighian tubule cells. The high density of mitochondria and their association with all the microvilli is indicative of a highly active secretory cell. The high concentration of glycogen in these cells and their intimate association with the hindgut suggest that they may, in addition, have a nutrient absorptive function. The role of the cryptonephric rectal complex in the glow-worm is discussed in the light of present knowledge gained from previous studies of coleopteran and larval lepidopteran cryptonephric systems. On structural grounds a model is proposed for the regulation of the ionic environment of the rectum, and the uptake and metabolism of organic material from the rectal lumen by this cryptonephric complex.     

Calcium transport from Malpighian tubules to puparial cuticle ofMusca autumnalis

Summary The transport of calcium from mineralized granules stored in the Malpighian tubules to the puparium of the face fly,Musca autumnalis De Geer, was studied. Calcium was transported directly from the tubules to the cuticle via the hemolymph. Little, if any, calcium entered the hindgut or other tissues during or prior to transport. A total of approximately 0.8 mg of calcium per larva was transported, beginning at the wandering stage; peak hemolymph concentrations occurred at anterior retraction. Hemolymph calcium levels subsequently decreased as puparial calcium increased. Puparial mineralization utilized most of the minerals stored during the larval stage, with lesser amounts of minerals being recovered in the adult or excreted. Deposition of mineral salts in the cuticle was accompanied by an increase in cuticular pH from 7.0 to 8.4. The house fly,Musca domestica L., which contains much lower concentrations of minerals in the puparial cuticle, exhibited no increase in cuticular pH during pupariation. Biomineralization of the face fly puparial cuticle appears to occur, in part, as a result of ionic equilibria involving calcium and magnesium phosphates and carbonates, which have relatively low solubility products at alkaline pH.Contribution No. 87-237-J from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, Kansas. Cooperative investigation between Agricultural Research Service, U.S. Department of Agriculture and the Kansas Agricultural Experiment Station. K.J.K. is a research chemist and adjunct professor at U.S. Grain Marketing Research Laboratory and Kansas State University, respectively. Mention of a proprietary product in this paper does not imply its approval by the USDA to the exclusion of other products that may also be suitable. Reprint requests to A.B. Broce     

Histological and ultrastructural characterization of the alimentary system of solifuges (Arachnida,Solifugae)

Solifuges are voracious and fast predators. Once having captured a prey item, mostly small arthropods or even small vertebrates, they start feeding on their prey by constant chewing movements with their huge chelicerae. At the same time, they squeeze out the soft tissue that passes the anterior lattice‐like part of the mouthparts. The digestion of the food takes place in the midgut, which is anatomically highly complex. It consists of the midgut tube from which numerous prosomal and opisthosomal diverticula and tubular lateral branches arise. The dimorphic epithelium of the midgut tube and the diverticula is constituted of digestive and secretory cells. The digestive cells are characterized by an apical tubulus system and contain nutritional vacuoles, lipids, spherites, and glycogen. Secretory cells contain a huge amount of rough endoplasmic reticulum and secretory vacuoles. The lateral branches are ultrastructurally similar to Malpighian tubules and are likely involved in excretion. In contrast to the midgut, the epithelium of the hindgut consists of only one type of cell overlain by a thin cuticle. Digested residuals are stored in the hindgut until defecation. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

Studies on water and ion transport in homopteran insects: ultrastructure and cytochemistry of the cicadoid and cercopoid Malpighian tubules and filter chamber

The filter chamber is a complex junction of anterior and posterior extremities of the midgut and Malpighian tubules. The sac-like anterior extremity, or filter chamber proper, comprises two cell types. These are large cuboidal cells which secrete a mucoprotein, and extremely thin cells which have regular tubular invaginations of the basal plasma membrane. The posterior extremity of the midgut and the internal Malpighian tubules coil round the filter chamber proper. They consist of thin epithelial cells identical in ultrastructure. The basal plasma membrane in these cells is formed into leaflets. A thin cellular sheath and thick muscle layers surround the filter chamber. The filter chamber proper is lined by the mucoprotein secretion of the cuboidal cells. This secretion appears to bind potassium ions. ATPase and alkaline phosphatase cannot be detected in the filter chamber epithelia. The structure and cytochemistry of the filter chamber suggests that water flows from filter chamber proper to midgut and Malpighian tubules by passive osmosis. This may be facilitated by ion binding in the filter chamber proper and by hydrostatic pressure engendered by contraction of the muscular coat. The Malpighian tubules appear to be structurally and chemically adapted for ion secretion by active transport and possibly for reabsorption in the Malpighian duct segment.     

Transport of sperm within the cloaca of the female red-spotted newt

The transport of sperm in the cloaca and adjacent regions of the female red-spotted newt was examined. It was found that within 1 min after sperm were introduced into the vent, they progressed in a random pattern past the apertures of the spermatheca (the glandular, sperm storage organ that opens from the anterior roof of the cloaca) forward to the anterior end of the cloaca and on into the posterior regions of the hindgut and bladder. Sperm did not enter the dorsal recess of the cloaca into which the oviducts and ureters open. After 1 day, few sperm remained within the cloaca lumen. Sperm were not transported into the cloacae of artificially inseminated, anesthetized females without prior administration of norepinephrine to their cloacal mounds. Treatment of the cloacal mounds of naturally inseminated females with an antagonist of neuromuscular transmission (lidocaine) decreased the numbers of sperm in the anterior cloaca relative to those of saline-injected control specimens. Neither dead newt sperm nor live rabbit sperm entered the spermatheca. Rabbit sperm, however, entered the oviduct. It is argued that passive and active mechanisms of sperm transport work in concert. Contractions of smooth muscle, which may be initiated during courtship, probably serve to draw sperm passively into the cloaca and up to and beyond the apertures of spermathecal tubules, but sperm, once in the vicinity of those apertures, probably swim actively into them.     

Formation of the hindgut cuticular lining during embryonic development of Porcellio scaber (Crustacea,Isopoda)

The hindgut and foregut in terrestrial isopod crustaceans are ectodermal parts of the digestive system and are lined by cuticle, an apical extracellular matrix secreted by epithelial cells. Morphogenesis of the digestive system was reported in previous studies, but differentiation of the gut cuticle was not followed in detail. This study is focused on ultrastructural analyses of hindgut apical matrices and cuticle in selected intramarsupial developmental stages of the terrestrial isopod Porcellio scaber in comparison to adult animals to obtain data on the hindgut cuticular lining differentiation. Our results show that in late embryos of stages 16 and 18 the apical matrix in the hindgut consists of loose material overlaid by a thin intensely ruffled electron dense lamina facing the lumen. The ultrastructural resemblance to the embryonic epidermal matrices described in several arthropods suggests a common principle in chitinous matrix differentiation. The hindgut matrix in the prehatching embryo of stage 19 shows characteristics of the hindgut cuticle, specifically alignment to the apical epithelial surface and a prominent electron dense layer of epicuticle. In the preceding embryonic stage – stage 18 – an electron dense lamina, closely apposed to the apical cell membrane, is evident and is considered as the first epicuticle formation. In marsupial mancae the advanced features of the hindgut cuticle and epithelium are evident: a more prominent epicuticular layer, formation of cuticular spines and an extensive apical labyrinth. In comparison to the hindgut cuticle of adults, the hindgut cuticle of marsupial manca and in particular the electron dense epicuticular layer are much thinner and the difference between cuticle architecture in the anterior chamber and in the papillate region is not yet distinguishable. Differences from the hindgut cuticle in adults imply not fully developed structure and function of the hindgut cuticle in marsupial manca, possibly related also to different environments, as mancae develop in marsupial fluid. Bacteria, evenly distributed within the homogenous electron dense material in the hindgut lumen, were observed only in one specimen of early marsupial manca. The morphological features of gut cuticle renewal are evident in the late marsupial mancae, and are similar to those observed in the exoskeleton.