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 localization of calcium in prothoracic gland cells of Galleria mellonella L. (Insecta,Lepidoptera) in relation to secretory activity

Summary Localization of intracellular calcium was demonstrated by precipitation with potassium hexahydroxoantimonate in the fixation medium containing osmium tetroxide or osmium tetroxide and glutaraldehyde. The presence of calcium in the precipitates was confirmed by X-ray microanalysis. Cells from active prothoracic glands contain more calcium deposits than inactive glands. The calcium precipitates are mainly localized in the nucleus, in the smooth endoplasmic reticulum, in the hyaloplasm and to a lesser degree in the mitochondria. These findings are consistent with the proposed role of calcium in the stimulation of steroidogenesis.     

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.     

Ultrastructural observations on the cuticular envelope in salt glands ofFrankenia pauciflora

Summary During five developmental stages in differentiation of salt glands in leaves ofFrankenia pauciflora, details of the deposition of incrusting material in the cuticular envelope,i.e., hydrophobic suberin and/or cutin, have been observed by means of transmission electron microscopy.Around each transfusion area in the cuticular envelope a conspicuous lamellate ring structure is found. Thin 3.5 nm lamellae associated with the plasmalemma around each ring structure appear to participate in the formation of tripartite structures showing a reversed contrast compared to the plasmalemma. Below the ring structure the cuticular envelope is divided into an outer fibrillar and an inner amorphous zone. A gradual transition between the tripartite lamellae of the ring structure and the amorphous material of the envelope is evident. Very dense material present between the lamellae appear to accumulate in the transition zone. The results are discussed in relation to basic structural features of various incrustations of lipid nature.     

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     

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.     

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.     

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.     

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.     

入侵植物水花生解剖学和组织化学染色研究

水花生(Alternanthera philoxeroides)因其表型可塑性、高生长速率和快速无性繁殖能适应水、陆生境.该文利用光学显微镜和荧光显微镜对水、陆生境的水花生不定根、茎解剖结构、组织化学特征及质外体通透性进行了研究.结果表明:(1)水生境下,其不定根皮层中具较大裂生型通气组织,无次生生长,内皮层具凯氏带且...     

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 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 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 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