Anatomical and ultrastructural changes of the floral nectary ofPisum sativum L. during flower development

Summary The floral nectary ofPisum sativum L. is situated on the receptacle at the base of the gynoecium. The gland receives phloem alone which departed the vascular bundles supplying the staminal column. Throughout the nectary, only the companion cells of the phloem exhibited wall ingrowths typical of transfer cells. Modified stomata on the nectary surface served as exits for nectar, but stomatal pores developed well before the commencement of secretion. Furthermore, stomatal pores on the nectary usually closed by occlusion, not by guard-cell movements. Pore occlusion was detected most frequently in post-secretory and secretory glands, and less commonly in pre-secretory nectaries. A quantitative stereological study revealed few changes in nectary fine structure between buds, flowers secreting nectar, and post-secretory flowers. Dissolution of abundant starch grains in plastids of subepidermal secretory cells when secretion commenced suggests that starch is a precursor of nectar carbohydrate production. Throughout nectary development, mitochondria were consistently the most plentiful organelle in both epidermal and subepidermal cells, and in addition to the relative paucity of dictyosomes, endoplasmic reticulum, and their associated vesicles, the evidence suggests that floral nectar secretion inP. sativum is an energy-requiring (eccrine) process, rather that granulocrine.Abbreviations ER endoplasmic reticulum - GA glutaraldehyde - SEM scanning electron microscopy     

Ultrastructure of the accessory glands of gene's organ in the cattle tick, Boophilus

The organization and ultrastructure of the accessory glands of the cattle tick, Boophilus microplus, are described. The glands consist of two groups of acinar cells situated on either side of Gene's organ. A single acinus consists of from eight to 12 cells and each cell is connected via an individual duct to pores on the dorsal surface of the mouthparts. The position of these pores is such that the secretion of the accessory glands is incorporated into the egg wax during oviposition. Each gland cell has striking quantities of smooth endoplasmic reticulum and numerous Golgi dictyosomes and appears to produce a secretion that is lipoidal in nature. Each cell secretes into its own individual lumen and is connected to a cuticular pore by a duct cell.     

Fine structure of the Nassonow's gland in the neotenic endoparasitic of female Xenos vesparum (Rossi) (Strepsiptera, Insecta)

Nassonow's gland consists of a number of cells with ducts that open on to the ventral surface of the brood canal in the cephalothoracic region of a neotenic female strepsipteran. The structural organization of the gland is reminiscent of the class 3 of the epidermal gland cells as defined by Noirot and Quennedey [Ann. Rev. Entomol. 19 (1974) 61], which consists of secretory and duct forming cells. The ultrastructure of the Nassonow's gland is described in female Xenos vesparum (Rossi) parasitic in the social wasp Polistes dominulus Christ. The large secretory cells are clustered in groups of three to four, rich in smooth endoplasmic reticulum and produce a secretion made up of lipids. In young females, just before mating, the ultrastructure of the cells and their inclusions indicate that they are active. In old-mated females the Nassonow's gland degenerates. Microvilli line an extracellular cavity and there are pores present in the irregularly thick cuticle of the efferent duct. The small duct forming cells, intermingle with epidermal cells, overlap secretory cells and produce a long efferent duct, the cuticle of which becomes thick close to its opening in the brood canal. Nassonow's gland could be the source of a sex pheromone, which might be capable of attracting the free-living male to a permanently endoparasitic female.     

麝鼠泌香期香囊腺形态及组织结构的研究

麝鼠香囊腺由腺细胞、支持细胞和排香管组成。其分泌腺属复管泡状腺。发育初期的腺泡胞质内含有大量的粗面内质同、光滑内质网、高尔基复合体、中心粒和线粒体、香腺细胞间连接发达,桥粒、半桥粒广为分布。胞质内含有电子致密度高和电子致密度低的两种分泌颗粒。其分泌方式为顶浆分泌。     

Age-dependent changes in structure and function of the male labial gland in Bombus terrestris

The cephalic region of the labial gland in the buff-tailed bumblebee, Bombus terrestris, consists of numerous acini (formed by associated secretory cells and a central lumen) and connecting ducts. Age-dependent changes in secretion production (both qualitative and quantitative) are associated with changes in the amount of rough endoplasmic reticulum (RER), Golgi apparatus, and smooth endoplasmic reticulum (SER). The main secretory organelle is RER in the youngest individuals (pharate, and less-than-a-day old males), Golgi apparatus in 1-day-old males, and SER in males older than 2 days. Secretory cell death starts at 5 days of age, with maximal longevity to 10 days. Pheromone production starts immediately after eclosion, with pheromone quantities increasing until day 7. 2,3-dihydrofarnesol, the main component of the male-marking pheromone, appears in 1-day-old male glands, and reaches a maximum at 7 days of age, when its presence in the gland starts to decrease gradually. Older glands contain compounds not present in young ones. Variation in pheromone quantity and composition are reflected sensitively in the response of the queen antennae. Though queen antennae responded to gland extracts of all ages examined, maximum sensitivity was observed in response to extracts of glands 2-10 days old, while extracts of older glands gradually lose their effectiveness. Both major and minor components of the labial gland secretion extract elicited queen antennal responses suggesting that the pheromone is a multicomponent blend. Age-dependent changes in pheromone production, accumulation and tuning of pheromone activity are all synchronized approximately with male flight from the hive.     

Intracellular pathway and kinetics of protein secretion in the coagulating gland of the mouse

The coagulating gland of male rodents is part of the prostatic complex. Various mechanisms of secretion have been postulated, in part because organelles commonly involved in the secretory process possess unusual features, such as extreme distension of the rough endoplasmic reticulum. In the present study, the pathway, kinetics, and mode of secretion in the coagulating gland of the mouse were studied by electron microscope autoradiography at intervals between 5 min and 8 h after administration of 3H-threonine. The percentage of grains associated with the rough endoplasmic reticulum was initially high and generally decreased throughout the experiment, while a pronounced rise in the proportion of grains associated with the Golgi apparatus and secretory granules was observed 6 h after injection of precursor. In addition, there was a smaller elevation in the percentage of grains over the Golgi apparatus and secretory granules between 1 and 4 h, and radioactive material first reached the lumen of the gland 4 h after injection of the precursor. Although the general pathway of intracellular transport of secretory protein resembles that in other cells, the results indicate that there are several unusual aspects to the secretory process in the coagulating gland. First, the rate of transport was markedly slower than in most other exocrine gland cells, since the bulk of the labeled protein did not reach the Golgi apparatus and secretory granules until 6 h after administration of precursor. This reflected prolonged retention of secretory products in the endoplasmic reticulum. Second, in addition to the major bolus of labeled material that traversed the cells at about 6 h, a smaller wave of radioactivity appeared to pass through the Golgi apparatus and secretory granules and reach the lumen earlier, within the first few hours after the injection. Finally, the primary mode of secretion in the coagulating gland appears to be merocrine because the secretory granules contained much labeled protein.     

Reduction capacity of untreated and of repeatedly isoproterenol treated parotid gland of the mouse

Osmium impregnation was used to show possible differences of reduction capacity of perinuclear space, rough endoplasmic reticulum and the Golgi apparatus of unstimulated mouse parotid gland and in the gland after repeated pharmacological doses of isoproterenol. There were some significant differences between the staining of acinar and duct cells. In all intercalated and striated duct cells the staining is dense in the perinuclear space and in the rough endoplasmic reticulum. Osmiophility was not detected in the Golgi complex of intercalated duct cells. The staining was also lacking in the perinuclear space and endoplasmic reticulum of the acinar cells. The cis face of the Golgi complex and numerous transitional vesicles in the acinar cells showed variability of the reduction capacity of their membrane segments. In chronically treated acinar cells Os black was lacking in the Golgi cisternae, except that the numerous transitional vesicles were heavily stained. These results reveal characteristic differences of reduction capacity of endomembrane compartments in different parotid glandular cells, as well as between untreated and treated acinar cells.     

Development of secretory activity in the seminal vesicle of the male migratory grasshopper,Melanoplus sanguinipes (fabr.) (Orthoptera : Acrididae)

This paper describes the ultrastructure of the seminal vesicle and the isoelectric focusing patterns of its secretion during sexual maturation and after allatectomy in Melanoplus sanguinipes (Fabr.) (Orthoptera : Acrididae). In epithelia from seminal vesicles of newly fledged males, the rough endoplasmic reticulum is well developed, and Golgi complexes are elaborate, which indicates the gland is metabolically active. The cells also contain large glycogen deposits and the lumen microvilli are well differentiated. These ultrastructural features are more dominant in 24-hr-old adults where the cytoplasm is clearly differentiated into basal and apical regions. Basally, the cytoplasm is dominated by rough endoplasmic reticulum, large Golgi complexes, glycogen deposits and numerous mitochondria, while the apical cytoplasm is filled with large secretory and/or lysosomal vesicles. Between days 3 and 7, the ultrastructural features change little other than the rough endoplasmic reticulum cisternae, which become vesicular. Analysis by isoelectric focusing shows that the amount of secretory protein increases with age until day 3, at which time the gland contains its full complement of secretion. In seminal vesicles from allatectomized insects, ultrastructural features of cells and isoelectric focusing patterns of the secretion arc identical to those from normal males.     

Morphological studies on secretion in the silk glands of the caddis fly larvae,Platyphylax designatus walker

Summary Actively secreting silk gland cells of caddis fly larvae show the following fine structure: a well developed rough-surfaced endoplasmic reticulum, continuity between roughsurfaced and smooth-surfaced endoplasmic reticulum adjacent to the Golgi saccules, dense material (secretion) in the margins of the Golgi saccules, some of which appear in the form of blebs and discrete membane bounded secretion granules; the latter seem to coalesce and migrate to the surface of the cell where they are discharged. Intracisternal granules appear in glands where the secretion cycle has apparently been interrupted. These observations suggest a secretion cycle for the silk glands comparable to that demonstrated by both morphological and experimental methods in certain other protein secreting cells: namely, synthesis by the ribosomes, transport to the Golgi complex through the cisternae of the endoplasmic reticulum, concentration by the Golgi complex and movement of the secretion granules through the cytoplasm to the surface of the cell where they are discharged.This research was supported by grants from the National Institutes of Health (RG-4706, 5479) and the National Science Foundation (G-9879).     

Reduction capacity of untreated and of repeatedly isoproterenol treated parotid gland of the mouse

Summary Osmium impregnation was used to show possible differences of reduction capacity of perinuclear space, rough endoplasmic reticulum and the Golgi apparatus of unstimulated mouse parotid gland and in the gland after repeated pharmacological doses of isoproterenol. There were some significant differences between the staining of acinar and duct cells. In all intercalated and striated duct cells the staining is dense in the perinuclear space and in the rough endoplasmic reticulum. Osmiophility was not detected in the Golgi complex of intercalated duct cells. The staining was also lacking in the perinuclear space and endoplasmic reticulum of the acinar cells. The cis face of the Golgi complex and numerous transitional vesicles in the acinar cells showed variability of the reduction capacity of their membrane segments. In chronically treated acinar cells Os black was lacking in the Golgi cisternae, except that the numerous transitional vesicles were heavily stained.These results reveal characteristic differences of reduction capacity of endomembrane compartments in different parotid glandular cells, as well as between untreated und treated acinar cells.     

Dufour gland of the digger wasp<Emphasis Type="Italic"> Liris niger:</Emphasis> structure and developmental and biochemical aspects

The tubiform Dufour gland in the digger wasp species Liris niger is about 1.0 mm long ( 0.15 mm). An alternating arrangement of longitudinal and circumferential bundles of striated muscle fibers surrounds the gland. The Dufour gland, together with the venom gland, enters the sting base and terminates in the sting. The glandular epithelium is monolayered. Glands about 3 day after imaginal ecdysis have an empty lumen but a thick lining epithelium. The gland cells are characterized by a well-developed vesicular smooth endoplasmic reticulum, sparse rough ER and numerous free ribosomes. They also exhibit several electron-lucent vesicles and autophagic vacuoles. Secretion of electron-dense material via the gland cuticle into the gland lumen is apparent. Glands more than 20 days after imaginal ecdysis display a large lumen and a thin epithelium. The cells show signs of degeneration with numerous cytolytic inclusions. Dufour gland liquid contains numerous polypeptides of molecular weights ranging from 14 to about 200 kDa. In addition the secretion consists predominantly of straight-chain hydrocarbons, accompanied by small amounts of esters. The major hydrocarbons are pentadecane and (Z)-8-heptadecene. Dufour gland secretion may have several functions: (1) the polypeptides might be involved in the gluing process of the eggs, while (2) the hydrocarbon oils may function as lubricants for the lancets and (3) might soften the secretion, thus allowing easier application of the glue. The lipophilic volatile material (4) might also be involved in pheromonal signaling.     

THE NUCLEAR ENVELOPE : ITS STRUCTURE AND RELATION TO CYTOPLASMIC MEMBRANES

An electron microscope study of thin sections of interphase cells has revealed the following:— Circular pores are formed in the double nuclear envelope by continuities between the inner and outer membranes which permit contact between the nucleoplasm and the cytoplasm unmediated by a well defined membrane. The pores, seen in sections normal to the nuclear envelope, are profiles of the ring-shaped structures described by others and seen in tangential section. The inner and outer nuclear membranes are continuous with one another and enclose the perinuclear space. The pores contain a diffuse, faintly particulate material. A survey of cells of the rat derived from the embryonic ectoderm, mesoderm, and endoderm, and of a protozoan and an alga has revealed pores in all tissues examined, without exception. It is concluded that pores in the nuclear envelope are a fundamental feature of all resting cells. In certain cells, the outer nuclear membrane is continuous with membranes of the endoplasmic reticulum, hence the perinuclear space is continuous with cavities enclosed by those membranes. There are indications that this is true for all resting cells, at least in a transitory way. On the basis of these observations, the hypothesis is made that two pathways of exchange exist between the nucleus and the cytoplasm; by way of the perinuclear space and cavities of the endoplasmic reticulum and by way of the pores in the nuclear envelope.     

Morphology and ultrastructure of a bacteria cultivation organ: the antennal glands of female European beewolves, Philanthus triangulum (Hymenoptera, Crabronidae)

Females of a solitary digger wasp, the European beewolf (Philanthus triangulum F.), cultivate symbiotic bacteria of the genus Streptomyces in specialized antennal glands. The streptomycetes are secreted in the subterranean brood cells and protect the offspring against mould fungi. We reconstructed the complex morphology of the antennal glands using 3D-visualization software, investigated the ultrastructure of the glands, and examine the role of the antennal glands as organs for the cultivation of the symbiotic bacteria. The bacteria are cultivated in five antennomeres within large reservoirs that consist of two slightly bent lobes. Each gland reservoir is bordered by a monolayered epithelium lined with a partially reinforced cuticle and when completely filled with bacteria it comprises about half of the antennomere's volume. The opening of the reservoir is covered by gelatinous appendage of the cuticle. The cells of the monolayered epithelium bordering each reservoir show basal invaginations, apical microvilli and numerous vesicles. Each reservoir is surrounded by approximately 400 class 3 gland units that are connected to the reservoir lumen through conducting canals. The class 3 gland cells contain numerous vesicles and a high density of rough endoplasmatic reticulum. In the reservoir lumen, large numbers of symbiotic Streptomyces bacteria are embedded in secretion droplets. Thus, the bacteria are apparently provided with large amounts of nutrients via the gland epithelium and the class 3 gland cell units.     

The nuclear envelope; its structure and relation to cytoplasmic membranes

An electron microscope study of thin sections of interphase cells has revealed the following:- Circular pores are formed in the double nuclear envelope by continuities between the inner and outer membranes which permit contact between the nucleoplasm and the cytoplasm unmediated by a well defined membrane. The pores, seen in sections normal to the nuclear envelope, are profiles of the ring-shaped structures described by others and seen in tangential section. The inner and outer nuclear membranes are continuous with one another and enclose the perinuclear space. The pores contain a diffuse, faintly particulate material. A survey of cells of the rat derived from the embryonic ectoderm, mesoderm, and endoderm, and of a protozoan and an alga has revealed pores in all tissues examined, without exception. It is concluded that pores in the nuclear envelope are a fundamental feature of all resting cells. In certain cells, the outer nuclear membrane is continuous with membranes of the endoplasmic reticulum, hence the perinuclear space is continuous with cavities enclosed by those membranes. There are indications that this is true for all resting cells, at least in a transitory way. On the basis of these observations, the hypothesis is made that two pathways of exchange exist between the nucleus and the cytoplasm; by way of the perinuclear space and cavities of the endoplasmic reticulum and by way of the pores in the nuclear envelope.     

锯缘青蟹窦腺显微和超微结构研究

借助光学和电子显微镜观察据缘青蟹（Ｓｃｙｌｌａ ｓｅｒｒａｔａ）窦腺的形态结构。窦腺位于眼柄视神经节内髓背侧近外髓处。窦腺呈羹状;腺体壁山神经分泌细胞的末梢和神经胶质细胞组成。神经末梢内充满了电子致密的神经分泌颗粒。根据颗粒的大小、形态及电子致密度等特征,可以区分出４种类型的神经末梢。一些末梢中的多形性颗粒可能是由Ⅱ型末梢中的颗粒转变而成的。一些现象表明,神经分泌物质可以通过胞吐作用或一种类似“顶浆分泌”的方式释放,从而说明神经激素的释放可能是多途径的．     

Ultrastructure of the salt glands of the mangrove,Avicennia marina (Forssk.) Vierh., as indicated by the use of selective membrane staining

Each salt-excreting gland of the mangrove Avicennia marina (Forsskål) Vierh. consists of two to four collecting cells, one stalk cell, and eight to twelve excretory cells. Differential membrane staining by zinc iodide-osmium tetroxide (as a post-fixative) or phosphotungstic acid (as a section-stain) was used to characterise the ultrastructure of the glands. A large amount of tubular endoplasmic reticulum was found in the stalk and excretory cells of the gland, but not in the collecting cells. The ultrastructural arrangement of the endoplasmic reticulum indicates that salt is loaded from the apoplasm into the endoplasmic reticulum of the symplasm at the base of the stalk cell, traverses both cell types in the endoplasmic reticulum, and is excreted at the outer edge of the gland by an eccrine-type mechanism. Increasing development of the tubular endoplasmic reticulum accompanied differentiation of the gland cells.Abbreviations ER endoplasmic reticulum - PTA phosphotungstic acid - ZIO zinc iodide-osmium tetroxide     

Prolonged osmification as an indicator of the differentiation process in the endomembrane system.

The technique of prolonged osmification was used in the analysis of reducing capacity of perinuclear space, endoplasmic reticulum and cis-Golgi cisternae in different epithelial cells during embryonic differentiation and immediately after the birth. Cells of the mouse gastric and intestinal epithelium and of the exocrine pancreas and mammary gland were analyzed. It was shown that endomembrane compartments exhibit high variability in their capacity to reduce OsO4 into lower valency oxides. Typical staining of cis-Golgi cisternae by osmium black does not occur before the cells achieve the developmental state in which production of specific products starts. The changes in stainability occurring from the perinuclear space and endoplasmic reticulum towards the cis-Golgi cisternae indicate a maturation pathway with no direct correlation to the chemical characteristic of the substances produced in different cell types. In the mammary gland the reduction capacity of endoplasmic reticulum disappeared with the intensive synthesis of lipids. Considering our previous results and those of other authors, the possible reasons for the observed dynamics in reducibility in particular segments of endomembraneous space are discussed.     

Fine structure and histochemistry of the spermathecal gland in the mealworm beetle, Tenebrio Molitor

The spermathecal accessory gland of female Tenebrio molitor is examined by histochemicai and electron microscopical techniques. Immediately after ecdysis of the female, neither Golgi regions nor the endoplasmic reticulum of the secretory cells are well developed. In two days' time, the cytoplasm is rich in rough endoplasmic reticulum and the Golgi areas are expanded. Membrane-bound droplets of secretion move from the Golgi zone to a central cavity, formed by the invaginated plasma membrane of this cell. As the secretion accumulates this cavity swells until the fourth day after ecdysis when the females first mate. An efferent cuticular ductule, ensheathed in a ductulecarrying cell, carries the product to the main axial duct of the tubular gland. By histochemical criteria, the product is a glycoprotein.     

Histology and ultrastructure of the glands associated with the porose areas on the gnathosoma ofRhipicephalus evertsi evertsi before and during oviposition

Histological and electronmicroscopical studies have shown that the subcuticular tissue associated with the porose areas of femaleRhipicephalus evertsi evertsi consists of paired multicellular, alveolar and lobularly arranged glands. At least two types of cells are clearly distinguishable, according with their location. Proximally, in direct association with the pores, cells with small and long nuclei are present. These cells are aligned along large, elongated lumina containing numerous microvilli and extend deep into the cuticular pores. They are separated from the extraintegumental space by cuticular valves. The distal gland sections are characterized by cells with large nuclei which are mostly arranged in the form of rosettes. These cells, which function as secretory cells, contain many mitochondria, smooth and rough endoplasmic reticulum and membrane-lined vesicles. The glands are always present in female ticks and their dorso-ventral extension increases continuously with feeding, reaching a maximum depth during oviposition.