Localization and fine structure of the female sex pheromone-producing glands in Bruchidius atrolineatus (PIC) (Coleoptera : Bruchidae)

The sex pheromone glands of female Bruchidius atrolineatus (Coleoptera: Bruchidae) have been localized by recording the electric response of the antenna of males subjected to a stream of air, containing the volatile sex pheromone (electroanntennography-EAG). Some 50 unicellular glands are distributed irregularly in the ventral and dorsal intersegmental membranes situated at the extremity of the pygidium, each gland containing a short ductule with an evacuation pore, 0.5–1 μm in diameter. The receiving canal is composed of a network of fine epicuticular filaments. The glands are type 3. The ultrastructure of these sex pheromone-producing glands is described in females whose production-emission activity had been previously verified with EAG. Deep basal invaginations and inflated intercellular spaces indicate the transport of substances from the hemolymph to the gland cells. The presence of numerous elongated mitochondria, diverse inclusions, vesicles containing crystalline bodies, and abundant apical microvilli, all reveal elevated cellular activity, which is never observed in young or diapausing females that do not produce sex pheromone. The ultrastructural differences in different types of females (sexually active or diapausing), combined with comparative EAG recordings obtained with intact females or those in which the suspected glandular zone was masked, made it possible to localize the glands.     

黑缘烟蟋螽丝腺结构

【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。     

Micromorphology of the malpighian tubules in the louse Pediculus humanus corporis (Anoplura)

The ultrastructure of the Malpighian tubes in human louse Pediculus humanus corporis has been studied. The cells of the Malpighian tubules have the uniform structure: the apical surface is covered with microvilli, the basal plasmatic membrana forms relatively small invaginations. The microvilli are most developed in cells of the proximal department of the Malpighian tubules. Microvilli of the apical surface of the cells do not contain mitochondria which are localized mainly in supranuclear part of the cell. Cells are lined with a homogenous basal membrane.     

Histology and ultrastructure of male mullerian gland of Uraeotyphlus narayani (Amphibia: Gymnophiona)

This study reports the anatomy, histology, and ultrastructure of the male Mullerian gland of the caecilian Uraeotyphlus narayani, based on dissections, light microscopic histological and histochemical preparations, and transmission electron microscopic observations. The posterior end of the Mullerian duct and the urinogenital duct of this caecilian join to form a common duct before opening into the cloaca. The boundary of the entire gland has a pleuroperitoneum, followed by smooth muscle fibers and connective tissue. The Mullerian gland is composed of numerous individual tubular glands separated from each other by connective tissue. Each gland has a duct, which joins the central Mullerian duct. The ducts of the tubular glands are also surrounded by abundant connective tissue. The tubular glands differ between the column and the base in regard to the outer boundary and the epithelial organization. The basement membrane of the column is so thick that amoeboid cells may not penetrate it, whereas that around the base of the gland is thin and appears to allow migration of amoeboid cells into and out of the basal aspect of the gland. The epithelium of the column has nonciliated secretory cells with basal nuclei and ciliated nonsecretory cells with apical nuclei. In the epithelium of the base there are secretory cells, ciliated cells, and amoeboid cells. The epithelium of ducts of the tubular glands is formed of ciliated dark cells and microvillated light cells. The epithelium of the central duct is formed of ciliated dark cells also possessing microvilli, ciliated light cells also possessing microvilli, and microvillated light cells that lack cilia. It is regressed during March to June when the testis lobes are in a state of quiescence. The Mullerian gland is active in secretion during July to February when the testis is active in spermatogenesis.     

Histology and ultrastructure of the caudal courtship glands of the red‐backed salamander,Plethodon cinereus (Amphibia: Plethodontidae)

Caudal courtship glands (CCGs) are sexually dimorphic glands described in the skin of the dorsal tail base of some male salamanders in the genera Desmognathus, Eurycea, and Plethodon in the family Plethodontidae. These glands are believed to deliver pheromones to females during courtship, when the female rests her chin on the dorsal tail base during the stereotypic tail straddling walk unique to plethodontids. Although CCGs have been studied histologically, no investigations of their ultrastructure have been made. This article presents the first study on the fine structure and seasonal variation of CCGs, using the plethodontid Plethodon cinereus. The CCGs vary seasonally in height and secretory activity. The mature secretory granules observed in males collected in October and April consist of oval, biphasic granules that are eosinophilic and give positive reactions to periodic acid‐Schiff for neutral carbohydrates but do not stain for acidic mucosusbtances or proteins with alcian blue and bromphenol blue, respectively. Granular glands, some of which contain mucous demilunes, are twice as large as CCGs, are syncytial (unlike CCGs), and stain for proteins. Mucous glands are similar in size to CCGs, but are basophilic, show no seasonal variation in secretory activity, and stain positive for acidic mucosubstances. CCGs do not resemble cytologically the sexually dimorphic mental glands of some plethodontids, which contain round or oval granules filled with an electron‐dense amorphous substance. The CCGs are similar histologically to sexually dimorphic skin glands described in some anurans, but more comparative work is needed. J. Morphol. 276:319–330, 2015. © 2014 Wiley Periodicals, Inc.     

Pheromone release by the two forms of Callosobruchus maculatus females: effects of age, temperature and host plant

Abstract. The influence of age, temperature and host plant on pheromone release was investigated in females of two forms of Callosobruchus maculatus (Coleoptera: Bruchidae), referred to as the flightless form and the flight form. The emission of pheromone seemed to be correlated with reproductive status: the flightless-form females which were sexually mature at emergence began to release pheromone on the first day following emergence. The flight-form females which exhibited no reproductive activity at emergence also showed a delayed emission of pheromone. The temperature conditions and the availability of host plant seeds had no apparent effect on pheromone release by the flightless form. In flight-form females pheromone release was stimulated by the presence of host plant seeds. Temperature seemed to affect the age at which females initiated pheromone release for the first time after emergence, pheromonal emission being brought forward slightly by higher temperature. All these results are discussed relative to the specific environment of each form.     

Electron microscopic studies on the pineal organ of the antarctic penguin, (Pygoscelis papua)

The pineal organ of the migratory antarctic penguin, Pygoscelis papua, has a lobular structure. Clusters formed by different types of parenchymal cells are separated by connective tissue septa containing blood vessels. The predominant cell type displays a well-developed Golgi complex, free ribosomes, clear and granular vesicles (secretory granules), and lysosomes. Other cell types found in the gland are supporting and ependymal-like cells. The former contain dense bodies and filament bundles, the latter possess abundant cilia and clusters of ribosomes. Typical photoreceptor elements are lacking. Blood vessels are located within a perivascular space bordered by basal laminae. This perivascular space extends between the basal protrusions of the parenchymal cells. The presence of pinocytotic vesicles, secretory granules and cytoplasmic processes in the vicinity of these spaces suggests active sites of transport and exchange of substances. Intercellular conaliculi-like spaces are surrounded by parenchymal cells rich in microvilli. These cancliculi are continuous with the cavities (invaginations) of secretory and other parenchymal cells.     

Ultrastructure of epidermal glands in neotenic reproductives of the termite Prorhinotermes simplex (Isoptera: Rhinotermitidae)

The ultrastructure of epidermal glands in neotenic reproductives of Prorhinotermes simplex is described and their development is compared among young and old neotenics of both sexes. Secretory cells forming the epidermal gland are attached to the cuticle all over the body. The glands are formed by class 1 and class 3 secretory cells and corresponding canal cells with secretory function. Class 1 cells are sandglass-like and class 3 secretory units are located among them. Class 1 cells contain predominantly tubular endoplasmic reticulum, the major part represents the smooth and the minor the rough form. Numerous electron dense granules occur in the cytoplasm, they are always disintegrated prior to be released. Class 3 secretory cells contain a large amount of vacuoles, which are always lucent in males while newly produced vacuoles are dense in females. Dense vacuoles are frequently transformed into lucent ones before being released. Canal cells are locally equipped with microvilli. The conducting canal is surrounded by an electron dense secretion of regular inner structure. The cytoplasm of the canal cell contains numerous mitochondria, rough endoplasmic reticulum and a large proportion of microtubules. The young neotenic reproductives differ from the old ones by a lower amount of secretory products. Epidermal glands probably produce substances inhibiting the occurrence of superfluous reproductives.     

The clypeal gland: A new exocrine gland in termite imagoes (Isoptera: Serritermitidae,Rhinotermitidae, Termitidae)

Social insects possess a rich set of exocrine organs producing diverse pheromones and defensive compounds. This is especially true for termite imagoes, which are equipped with several glands producing, among others, sex pheromones and defensive compounds protecting imagoes during the dispersal flight and colony foundation. Here, we describe the clypeal gland, a new termite exocrine organ occurring in the labro-clypeal region of imagoes of most Rhinotermitidae, Serritermitidae and Termitidae species. The clypeal gland of Coptotermes testaceus consists of class 1 (modified epidermal cell) and class 3 (bicellular gland unit) secretory cells. Ultrastructural features suggest that the gland secretes volatile compounds and proteins, probably after starting the reproduction. One peculiar feature of the gland is the presence of multiple secretory canals in a single canal cell, a feature never observed before in other insect glands. Although the function of the gland remains unknown, we hypothesize that it could produce secretion signalling the presence of functional reproductives or their need to be fed.     

Fine structure of the pygidial glands of Bledius mandibularis (coleoptera : staphylinidae)

The pygidial glands of B. mandibularis produce a mixture of terpenes, fatty acid derivatives, and a benzoquinone. The morphology of these glands is described with particular attention to the ultrastructure of the secretory cells and their efferent ductules. Each functional secretory unit consists of two secretory cells (cortical and medullary) both of which are associated with a common extracellular cuticular ductule. The fenestrated tip of the ductule lies in a cavity bounded by the invaginated plasma membrane of the cortical cell; within the cavity surrounded by the medullary cell, the ductule is divided into a bulb region (where a spherical mass of fine cylinders surrounds the ductule itself) and an unfenestrated switchback region. Inflated cisternae of rough endoplasmic reticulum, filled with flocculent material of low electron density, are abundant in the cortical cytoplasm, and presumably represent primary secretory product en route to the cavity of this cell. The plasma membrane bounding this cavity is much infolded, and the inner surface of this membrane is studded with fine particles. In contrast, few cisternae are inflated in the medullary cell and the corresponding infolded plasma membrane is smooth. The manner in which both cells may cooperate to produce the heterogeneous secretory product is discussed.     

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.     

The epithelium of the middle ear in the guinea pig

Summary An electron microscopic study of aldehyde and osmium fixed normal guinea pig middle ear epithelium was made. Numerous branching microvilli occur between the cilia of the ciliated cells. The granules of the secretory cells are always surrounded by a membrane, and they vary in their content of electron dense substance. Half desmosomes are frequent in basal cells. The squamous epithelial cells of the bulla contain few microvilli and pinocytoric invaginations. In the basal part of the squamous epithelium dilations of the intercellular clefts often occur. The luminal part of the intercellular clefts are closed by multiple tight junctions.     

Ultrastructure of the midgut and the adhering tubular salivary glands of Frankliniella occidentalis (Pergande) (Thysanoptera : Thripidae)

The ultrastructure of the midgut and the tubular salivary glands of Frankliniella occidentalis (Thysanoptera : Thripidae) is described. The microvilli have 2 different types of glycocalyx: in the anterior part of the midgut they are surrounded by a myelin-like membrane; in the posterior region, the microvilli have numerous rod-like projections arranged to form a continuous layer. Microfilaments longitudinally cross each microvillus; the microfilaments contain F-actin. Tubular salivary glands flank the midgut but do not fuse with it. The distal part of these glands have microvillated cells containing large amounts of electron-transparent material. The cells of the proximal part are lined with a thin cuticle.     

Fine structure of the integumental glands of a termite soldier

The ultrastructure of some integumental glands occurring in the head, thorax and abdomen of K. flavicollis soldiers is described. The secretory units consist of two cells, the canal cell and the secretory cell (this latter filled with secretion granules). A cylindrical and distorted extracellular space, or reservoir, with an irregular outline is lined by short microvilli. The end-apparatus is made up of small overlapping cuticular laminae which in section resemble small wavy rods. The ample distribution of the units has led the authors to consider them dermal glands. Scanning electron micrographs confirm that the glands' activity consists in the secretion of material which then spreads over the surface of the integument. The dissimilar appearance of the secretion granules present in glands of different soldiers suggests that the electron-lucid granules and the granules with fibrils are two completely different secretions at different ages of the animal. The authors do not therefore rule out the hypothesis that these integumental glands may later produce or release pheromones.     

Adhesive glands in the Pterastericolidae (Plathelminthes,Rhabdocoela)

Summary The ultrastructure of anteroventral gland cells with processes penetrating the epidermis inPterastericola bergensis, P. fedotovi, P. pellucida and the undescribedP. (sp. Rottnest) was studied with transmission and scanning electron microscopy. Specimens ofP. pellucida were shock frozen in situ in the epithelium of their asteroid host to study the function of the glands. Secretory products released from the gland cell processes fan out towards the host epithelium. The glands are concluded to have an adhesive function. They are compared with similar structures in Neodermata and other rhabdocoel taxa. The phylogenetic significance of the glands is discussed.Abbreviations b basal lamina - c cilium - cr ciliary rootlets - d septate desmosome - g gland cell process - gc gland cell - h host epithelium - m mitochondria - mc muscle cell - mv microvilli - mt microtubules - n nucleus - o ootype - pm plasma membrane - s secretory granule - sm secretory material released from dissolving secretory granules     

The ultrastructure and histochemistry of the spermathecae of Tubifex tubifex (Annelida: Oligochaeta)

The wall of the spermathecal ampulla in Tubifex tubifex consists of epithelial, muscular and peritoneal layers. The epithelial surface contains closely microvilli while lateral and basal plasma membranes are extensively convoluted. Epithelial cytoplasm exhibits a vertical zonation of subcellular components. The distal zone contains filiform secretory particles which are orientated perpendicular to the apical surface; extrusion occurs by their fusion with the plasma membrane between the bases of neighbouring microvilli. Mitochondiral and Golgi zones, the latter containing the nucleus, subtend the distal zone. The basal zone, composed of vertical compartments formed by the folded plasma membrane, is rich in α-glycogen rosettes. The distal epithelium and lumen material contain neutral mucopolysaccharides and carboxylated acid mucopolysaccharides in conjunction with neutral protein. The ultrastructure of the spermathecal duct wall is comparable with that of the ampulla but is characterized by extremely long microvilli and a prominent musculature.     

Ultrastructure du canal des glandes agrégées et flagelliformes d'Araneus diadematus Clerck (Araneae,Araneidae)

Summary The excretory ducts of the silk glands which produce the viscid spiral of the webs ofAraneus diadematus show a complex structure. The duct of aggregate glands consists of three superposed types of cells. Several connective layers cover large and irregular nodule-forming cells which are rich in glycogen and mitochondria surrounded by invaginations of the plasma membranes. The internal cells, whose apical poles are lined by a cuticular intima, would be quite ordinary if not for the fact that they often carry large vacuoles which seem to empty themselves by exocytosis. Activity in the nodule cells is perceived from variations in the glycogen level and from the appearance of the mitochondria. Internal cells of the duct, when within the posterior spinneret, gradually acquire the characteristics of absorbing cells.The duct of flagelliform glands consists of two types of cells. The external cells, bounded by a simple basal lamina, are rich in mitochondria, glycogen, and invaginations of the plasma membranes; their activity is shown by variations in glycogen level and the extent of the extracellular spaces. The internal cells show numerous mitochondria either at the apical or basal poles, variable glycogen levels, long microvilli, and signs of apical absorption by pinocytosis; the sub-cuticular layer of the intima is particularly thick.We propose a functional interpretation of the aspects described above, and discuss it in terms of recent data on the chemical composition of silks. The excretory ducts are held to modify, by their activity, the secretory products of both types of glands. Solutes, especially phosphate ions, cross both cells and intima and would enter the glue of the aggregate glands which then undergoes partial dehydration in the posterior spinnerets. The product of the flagelliform glands seems to all appearance dehydrated during its passage in the duct and up to about the half-way through the posterior spinnerets. The liquid would flow through an extracellular path below the apical septate junctions of the internal cells. This study therefore favours attributing important role to the excretory ducts of silk glands in the final phase of the formation of silk fibres by spiders.     

Fine structure of submandibular glands of mice with testicular feminization (Tfm/Y)

Summary The fine structure of the submandibular gland of the mouse with testicular feminization (Tfm/Y) was studied by light and electron microscopy. The architecture of the Tfm/Y gland proved to be rather similar to that of the normal female mouse in both tubular ratio and structure. Granular convoluted tubular cells in Tfm/Y mice characteristically had fewer secretory granules and increased cytoplasmic vacuoles than normal littermates, suggesting an altered synthesis of secretory granules in this cell type of the Tfm/Y mouse. Moreover, there were differences in the ultrastructure of submandibular glands between Tfm/Y and normal female mice. In the gland of the Tfm/Y mouse, basal striations of the striated secretory tubular cells were not so developed and granular intercalated duct cells were less than those of normal females. These findings support the evidence that the secretory tubule of the mouse submandibular gland responds to androgens, resulting in accentuated development in the male, while also suggesting the possibility that the mouse submandibular gland is regulated by other factors which lead to the prominent sexual dimorphism observed in this gland.     

Ultrastructure of the Male Accessory Glands and Sperm Ducts of Cylindrotaenia hickmani(Cestoda,Cyclophyllidea)

Abstract The ultrastructure of unicellular accessory glands (= prostate glands) and external male ducts of the cestode Cylindrotaenia hickmaniare described. Accessory glands open into the lumen of the external common sperm duct (= external vas deferens). The gland cells contain abundant endoplasmic reticulum, Golgi bodies and secretory bodies, and have elongate necks that pierce the apical cytoplasm of the duct. Cell contact with the apical cytoplasm of the sperm duct is mediated by septate desmosomes. Accessory glands secrete spherical particles, with a diameter of approximately 70 nm, that adhere to spermatozoa. The roles of these accessory glands may relate to activity of the sperm or development of the female system after insemination. Paired sperm ducts arise from testes, and unite to form a common sperm duct. Each duct consists of a tubular anucleate cytoplasmic region which is supported by nucleated cytons that lie sunken in the parenchyma. The apical cytoplasm of the paired sperm ducts (= vasa efferentia) possesses apical microvilli and abundant mitochondria, but few other cytoplasmic features. The apical cytoplasm of the common sperm duct possesses sparse apical microvilli and numerous electronlucent vesicles. The male gonoducts form an elongate syncytium which is markedly polarized along the length of the ducts. The ducts also display apical–basal polarity in that sunken nucleated cytons support the apical cytoplasm which in turn has distinct basal and apical domains.