The spermathecal complex in Ips typographus (L.): Differentiation of the spermathecal gland related to age and reproductive state

The spermathecal complex of the bark beetle, Ips typographus, comprises the following elements: spermathecal duct, spermatheca and spermathecal gland. The spermathecal duct connects the vagina and the spermatheca and consists of a cuticular tube surrounded by an epithelial layer and circular muscles. The spermatheca is bottle-shaped and has a cuticle-lined lumen. Muscles are attached to both ends of the spermatheca. The spermathecal gland which is connected to the spermatheca possesses three cell types: glandular, hypodermal, and ductule. The glandular cells have different structural characteristics depending on the age and reproductive state of the females. After the emergence of the brood, two different kinds of secretory material are present in the glandular cells. There is evidence that one type of secretion is emitted during the first few days after brood emergence, while the other type accumulates to be secreted during later stages.     

Ultrastructural and histochemical observations on the tegument of Gastrodiscoides hominis (Paramphistoma: Digenea)

The tegument of the paramphistome, Gastrodiscoides hominis, is basically similar to that of other digeneans. It is folded into concentrically arranged furrows and ridges bearing numerous tightly packed tubercules, and extends into the oral cavity. An area of specialized tegument is present on the ventral surface, anterior to the disc region. Mitochondria are absent from the tegumental syncytium and underlying tegumental cells, suggesting that the tegument may serve principally as a protective layer rather than in active uptake phenomena. However, extensions of the lymph and parenchyma systems are closely associated with the base of the tegumental syncytium and may provide ATP for active processes. Ciliated and non-ciliated sensory papillae are present, particularly around the oral opening. Numerous lymph channels are present in the sub-tegument and may be involved in osmoregulation.     

The digestive gland of Viviparus ater (Mollusca, Gastropoda, Prosobranchia): an ultrastructural and histochemical study

The digestive gland of Viviparus ater was studied using histochemical and ultrastructural methods. Only one cell type was observed in the tubule epithelium of the gland. The cells are involved in an endocytotic process mediated by clathrin-coated vesicles and in the intracellular digestion of food materials (thus they can be regarded as digestive cells). The different stages of digestion and exocytotic extrusion of residual bodies into the tubule lumen were shown by electron microscopy. Very few, small mucocytes are scattered among the digestive cells. Calcium concretions, glycogen-containing cells and endocrine cells are scattered in the area of connective tissue present among the digestive tubules.     

Labial gland disease in the genusFormica (Formicidae,Hymenoptera)

Summary Labial gland disease causes swelling of the labial glands in the pupal stage inFormica species. The resulting adults have enlarged thoraces and are called secretergates (Wasmann's pseudogynes). They infect the younger larvae, probably during feeding. The agent of the disease is unknown. It soon becomes non-infectious outside the labial glands. Diseased females were not seen to feed larvae. Yet their offspring contained secretergates. The discrepancy remains unexplained.     

Ultrastructural observations on gastrodermal regeneration in the planarian Dugesia japonica (Turbellaria)

The earliest detectable change during regeneration of the gastrodermis in Dugesia japonica was an aggregation of regenerative cells underneath the gastrodermis remaining at the wound margin. The gastrodermal cells in experimental regenerates retained some of their original characters and presented no indication of cell dedifferentiation. The regenerative cells came into contact with the basal surface of gastrodermal cells, forming stratified cell layers. Differentiation of these cells into gastrodermal cells was initiated by the development of synthetic organelles within their cytoplasm. These differentiating cells gave rise to two different types of gastrodermal cells, namely phagocytic cells and sphere cells. In later stages, there was an apparent movement of differentiated gastrodermal cells towards the parenchyma.     

Ultrastructural observations on the oogenesis of Triops cancriformis (Crustacea,Notostraca)

Summary The first stages of the oogenesis of Triops cancriformis have been studied. At the outset the oocyte is smaller than the nurse cells. Meiosis begins with typical synaptonemal complexes. The significance of these complexes and of some other peculiar structures of germ cells, i.e., pore complexes and annuli within the nucleus, and annulate lamellae within the cytoplasm are discussed. The morphofunctional uniformity of some cytoplasmic structures (annulate lamellae, concentrically arranged ER, and yolk globules) in the oocyte as well as its nurse cells is also discussed.     

Ultrastructural observations on the oogenesis of Triops cancriformis (Crustacea,Notostraca)

Summary Each ovarian follicle of Triops cancriformis is four-celled; these cells (one oocyte and three nurse cells) are interconnected by cytoplasmic bridges. In the course of differentiation, the nurse cells are early recognizable; they increase in size more than the oocyte and their nuclei contain many nucleoli. For the first time in Arthropoda, yolk globules are reported to be present in nurse cell cytoplasm; these globules arise from the smooth endoplasmic reticulum. The functional significance of the intercellular bridges and the trophic role of the nurse cells are discussed.The authors are grateful to Dr. Bruno Sabelli for his support and to Mr. Francesco Monte for his technical assistance     

Exploration of wheat leaves byCoccinella septempunctata L. (Coleoptera,Coccinellidae) larvae

A new method for the quantification of insect movements on leaves is presented and applied to larvae of a wheat aphid predator, C. septempunctata. The method results from behavioral definition of positions adopted by this predator during its advance along the wheat leaf. Through a factor analysis of multiple correspondences, the method allowed specification of some aspects of predator movements on plants, especially the frequency of position associations, to give a new definition of local search and to describe some behavioral interactions with aphids. The consequences for predator efficiency are discussed.     

Electron microscopic and histochemical investigations of the atretic oocyte of Perca fluviatilis L. (Teleostei)

Summary The regression of atretic oocytes in Perca fluviatilis was studied by histochemical, light and electron microscopic methods. The course of regression can be divided into three stages, the first two comprising the dissolution of the atretic oocyte and its phagocytosis by the granulosa cells of the follicular epithelium, and the third stage consisting of the dissolution of the granulosa cells themselves. The ultrastructure in all three stages shows only features related to phagocytosis and lysosome formation. In particular, there is no agranular endoplasmic reticulum formed within the phagocytically active granulosa cells, nor is there any 3-hydroxysteroid dehydrogenase activity (3-HSD). Large yellow-orange pigments, formed during the third stage of regression, are ascribed to a relative deficiency of lysosomes in lipid digestion, and do not result from a preceeding steroid-synthesising phase as in mammalian corpora lutea. Thus, the atretic oocyte of P. fluviatilis is considered not to give rise to a corpus luteum formation with endocrine function, but merely represents a degenerative structure.     

SEM observations on seeds ofStriga spp. andBuchnera americana (Scrophulariaceae)

Seeds of the root parasitesStriga (several spp.) andBuchnera americana were examined by means of SEM. The surface patterns of the seeds in both genera resemble each other closely, especially those ofS. angustifolia andB. americana. SomeStriga spp. can be clearly distinguished by their surface characteristics, while this is quite difficult in others. The taxonomic value of the seed surface features ofStriga andBuchnera is discussed.     

Metamorphic changes in the central projects of hair sensilla inTenebrio molitor L. (Insecta: Coleoptera)

Summary This paper describes the afferent projections of hair sensilla of the pro- and mesothoracic legs and the lateral thoracic sclerites of larval and adultTenebrio molitor and the corresponding set of pupal hair sensilla. The sensory neurons that innervate the hair sensilla of larval or adult insects project somatotopically into the thoracic neuropil. Different types of sensilla on the same region of the body surface project to the same zone of the ipsilateral thoracic ventral neuropil but exhibit different arborization patterns. Although there is a profound reorganization of body surface sensilla, the basic somatotopic layout of the larva is maintained in the adult. The sensory neurons that innervate the pupal hair sensilla possess central projections similar to those of the corresponding adult sensory neurons. The central projections of pupal sensory neurons are somatotopically oriented. Their projection pattern is serially homologous in the thoracic and the abdominal ganglia. The central projection pattern of the described pupal sensory neurons is constant throughout pupation. MAb 22C10 immunoreactivity allows an estimate of the timing of the early differentiation of the imaginal sensory neurons originating during pupation. Ablation experiments indicate that pupal sensory neurons influence the central projection pattern of the differentiating imaginal sensory neurons.     

Ultrastructural appearance of neurosecretory granules in the sinus gland of the crab after different fixation procedures

Summary The appearance of neurosecretory granules in the crab sinus gland was studied after fixation at different pHs. Whereas at pH 7.0 the neurosecretory granules were pleomorphic with respect to electron density, at pH 5.0 or 6.0 all the granules remained electron dense. The possible role of maturation as an explanation of this observation is discussed.ERA 493 CNRS     

The ultrastructure of the sinus gland of the crayfish Astacus leptodactylus (Nordmann)

Summary An ultrastructural study of the sinus gland of the crayfish Astacus leptodactylus demonstrates that this gland is mainly composed of glial cells, axons and axon terminals. On the basis of the size, shape and electron density of the neurosecretory granules, we could distinguish five different types of axon terminals.     

Ultrastructural observations on the lung of the emperor penguin (Aptenodytes forsten)

Summary Of all avian species the emperor penguin is the best adapted bird to attain the greatest diving depths and diving durations. Therefore the lung of this bird was investigated with electron-microscopic, i.e., freeze-fracture and thin-section methods. The parabronchi are surrounded by bundles of smooth muscle cells innervated by varicosities of autonomic nerves. The parabronchial epithelium is flat, bears a few microvilli and does not show any conspicuous ultrastructural specializations; only individual cells contain secretory granules. The atrial epithelial cells bear apical microvilli and are interconnected by adhering and tight junctions (5–10 sealing strands), the latter presumably forming an effective barrier against paracellular fluid movements. The cells contain lamellar inclusions of two types: (i) round membrane-bounded granules, the lamellar content of which is fixation-labile, and (ii) large polymorphic compact deposits of well-preserved lamellae. In both types of inclusions the individual lamellae can be of trilaminar appearance, whereas their fracture faces are smooth. Lamellar material also covers the epithelium of atria, infundibula and air capillaries. In thin areas the diameter of the morphological blood-air barrier measures 220–330 nm. Usually the endothelium of the blood capillaries is thicker (40–180 nm) than the air capillary epithelium (25–150 nm). Both epithelium and endothelium are interconnected by tight junctions, which seem to be more extensive and presumably tighter in the epithelium than in the endothelium. Frequently the common basal lamina is the thickest individual component of the blood-air barrier, measuring between 170–230 nm. Often collagen fibrils occur in this area of the barrier. In comparison with that of other birds the entire blood-air barrier of the emperor penguin is relatively thick, probably owing to an adaptation of the lung tissue which must resist high hydrostatic pressure during diving excursions.     

The ultrastructure of the sinus gland of Gammarus oceanicus (Crustacea: Amphipoda)

Summary The sinus gland of Gammarus oceanicus, like that of other crustaceans, is composed of three elements: neurosecretory axons, glial cells and stromal sheath. Five neurosecretory axon types are identified on the basis of granule diameter, shape, and electron density, and axon matrix density. Exocytosis appears to be the major release mechanism of neurosecretory material. The preterminal regions of neurosecretory axons contain axoplasmic reticulum and neurotubules. Their arrangement in the axon and relationship with one another suggest a transport function. Multilamellar bodies are found in the terminal regions of neurosecretory axons. They arise from mitochondria and may be involved in granulolysis.The technical assistance of G.A. Bance, statistical assistance of D. MacCharles and D.W. Hagen, and financial support provided by the University of New Brunswick Research Fund to K.H. are gratefully acknowledged     

Pro-oxidant and antioxidant processes in gas gland and other tissues of cod (Gadus morhua)

Partial reduction of molecular oxygen produces reactive oxyradicals, including the superoxide anion radical (O _- ² ) and hydroxyl radical (·OH). The gas gland functions under hyperoxic and acidic conditions and therefore is likely to be subjected to enhanced oxidative stress. Aspects of pro- and antioxidant processes in gas gland were compared with other tissues likely to be subject to differing degrees of oxyradical production, viz. liver (site of chemically-mediated oxyradical production), gills and skeletal muscle. Antioxidant enzyme activities (superoxide dismutase, catalase, selenium-dependent and total glutathione peroxidase) per g wet weight were highest in liver and lowest in muscle. Catalase and glutathione peroxidase activies per g wet weight were higher in gills than in gas gland, whereas the reverse was seen for superoxide dismutase. Cytosolic superoxide dismutase activities per mg protein were two- and nine-fold higher in gas gland than in liver and gills. The pH characteristics of the antioxidant enzymes were generally similar in all the tissues. Glutathione, vitamin E and unsaturated (peroxidizable) lipid levels were generally highest in liver followed by gas gland. Lipid peroxidation (malonaldehyde equivalents) was evident in all tissues except gas gland. Hydrogen peroxide and O _- ² were involved in the NAD(P)H-dependent ferric/EDTA-mediated formation of ·OH (as measured by 2-keto-4-methiolbutyrate oxidation) by mitochondrial and postmitochondrial fractions of gas gland. Tissue maximal potentials for ·OH production paralled superoxide dismutase but not catalase or glutathione peroxidase activities. Overall, the results confirm the presence of effective antioxidant defences in gas gland and support previous workers' contentions of a central role for superoxide dismutase in this process.Abbreviations EDTA di-sodium ethylenediaminetetra-acetic acid - G-6-P glucose-6-phosphate - GPX total glutathione peroxidase - GSH reduced glutathione - GSSG oxidised glutathione - GST glutathion-S-transferase - HPLC high performance liquid chromatography - KMBA 2-keto-4-methiolbutyric acid - MOPS 3-[N-morpholino] propane-sulphonic acid - PMS postmitochondrial supernatant - Se-GPX selenium-dependent glutathion peroxidase - SOD superoxide dismutase - TCA trichloroacetic acid     

Ultrastructural localization of acid phosphatase in the pollen tube of Prunus avium L. (sweet cherry)

The pollen tube of Prunus avium (cherry) consists of a growth zone of vesicles at the tip and an assemblage of organelles typical of an actively metabolizing cell. Electron opaque globules are closely associated with the plasma membrane and fibrillar cell wall layer at the tip. Acid phosphatase (EC 3.1.3.2) activity is localized in the membranes of 120 nm vesicles and ER system, the lumen of 50 nm vesicles, the plasma membrane and the tube nucleus.     

Ultrastructural,cyto- and biochemical observations during turnover of plasma membrane in duck salt gland

Summary The mechanism of plasma membrane turnover was investigated using the duckling salt gland as a model system. Feeding fresh water to saltstressed ducklings results in a decrease in the Na, K-ATPase in salt gland to nonstressed levels in about 7 days, as measured by ATP hydrolysis and ³H-ouabain binding. Electron micrographs reveal that this is accompanied by a decrease in plasma membrane infoldings on the basal and lateral borders of gland secretory cells. Simultaneously there is an increase in filamentous material and a rise in acid phosphatase and peptidase activities in these cells. Cytochemistry shows that the acid phosphatase activity is mostly associated with the basal or basolateral regions of secretory cells. These observations could indicate that the removal of plasma membrane components is accomplished by internalization and digestion within the secretory cells.     

The ultrastructure of the androgenic gland in Porcellio scaber Latr. (terrestrial isopods)

Summary This paper presents the normal ultrastructural features of the androgenic gland in Porcellio scaber. It describes the changes in the organelles of its cells through the course of the secretory cycle, which terminates with the regression and destruction of these holocrine glandular cells. As products of this activity, the electron-opaque bodies (granules, lysosomes, agglomerates) and clear substances accumulate in the cytoplasm. With the destruction of the cell membrane, the entire cell content passes into the spaces of the haemocoele. The morphological modifications of the mitochondria and rough endoplasmic reticulum are the most striking changes.

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Résumé Les auteurs présentent, dans ce travail, les aspects ultrastructuraux normaux de la glande androgène chez l'oniscoïde Porcellio scaber. On montre, par des phases successives, les modifications morpho-fonctionnelles des organites cellulaires jusqu'à la fin du cycle sécrétoire, qui finit par la dégradation et la destruction des cellules glandulaires, dont la fonction est de type holocrin. Comme produits de cette activité, des corps éléctrono-opaques (grains, agglomerats, lysosomes) et des substances claires apparaissent dans le cytoplasme. Par la destruction de la membrane plasmique, tout le contenu cellulaire est éliminé dans les espaces haemocoeliens, soit par écoulement soit par fragments. Le RE et le chondriome subissent les modifications les plus spectaculaires.