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At least 19 recordsLinked to original sources
PubMed1979

The midgut of Tomocerus minor Lubbock (insecta, collembola): ultrastructure, cytochemistry, ageing and renewal during a moulting cycle.

The midgut cells of Tomocerus minor (Insecta, Collembola) were examined with the electron microscope and cytochemically. The midgut epithelium consists of a series of cells characterised by numerous mineral concretions scattered throughout the cytoplasm. Mitochondria are abundant; microvilli are well developed at the apical surface of the cell. A zonula continua (continuous junction) characterises the apical contact region of these cells. Polysaccharides, glycoproteins and carbohydrate components have been demonstrated on the surface of microvilli. Peritrophic membranes surround the food bolus and preserve midgut cells from mechanical abrasion. Lysosomes are present during the alimentary period and show strong acid phosphatase activity. During an intermoulting cycle, two stages can be observed: (1) the postexuvial feeding period during which cytoplasmic extrusions appear at the apical part of the cell: lysosomes increase in number and autophagic vacuoles appear. (2) The preexuvial fasting period; a new epithelium grows beneath the old one and pushes it into the lumen. Degeneration processes can be observed in the old epithelium. This excretory reactivity of the midgut epithelium has been compared to the cycle of the cuticle.

Acid Phosphatase↗
PubMed1977

Comparative analysis of the hindgut in two species of protura (Insecta, Apterygota).

The proturan hindgut consists of two regions, with different ultrastructure. The anterior region is organized into three primary longitudinal folds alternating with three smaller, secondary ones. In Acerentomon each primary fold in a cross section contains one or two cells showing all the structures which are involved in water reabsorption. The cells of the secondary folds do not seem engaged in a similar function. In Eosentomon the primary folds present a more complicated organization. Each of them consists of one central cell concerned with reabsorption and two lateral ones. Beneath these cells, on both sides of the fold there is a longitudinal muscle fiber. The posterior region of the hindgut does not seem capable of modifying the gut contents.

Animals↗
PubMed1977

Sense organs on the antennal flagellum of psocids (Insecta, Psocoptera).

The sense organs on the antennal flagella of five species of winged psocids belonging to two families of Psocoptera, Psocidae and Leptopsocidae, have been examined, All agree in possessing tactile hairs, thick-walled chemoreceptors and long, porous chemoreceptors. Thin-walled chemoreceptors were identified in all species except Metylophorous novaescotiae. Coeloconic chemoreceptors were present in all species except Echmepteryx hageni. Campaniform sense organs were found only in Metylophorus novaescotiae and Psocus leidyi.

Animals↗
PubMed1976

Structure and function of prothoracic glands and oenocytes in embryos and last larval instars of Oncopeltus fasciatus Dallas (Insecta, Heteroptera).

1. Active prothoracic glands and oenocytes of last larval stage are both characteristized by well-developed smooth and rough endoplasmic reticulum (ER). Prothoracic glands also show plasma membrane infoldings, but not oenocytes which contain a large number of pleomorphic vesicles. 2. The fine structure of embryonic oenocytes corresponds after blastokinesis with that of active larval and adult cells. Thus, an activity in the late embryo can be assumed. Embryonic prothoracic glands reveal no signs of activity: smooth and rough ER are absent. The subcellular structure resembles that of organ anlagen, i.e. not yet fully differentiated tissue. Hormone synthesis is not likely. 3. Ecdysone titer was determined throughout embryonic development and in mature adults. Although prothoracic glands break down during adult ecdysis, imagines contain in the Calliphora-bioassay active factors: females 0.9 CU/g and males 0.5 CU/g. As sites of synthesis the oenocytes are suggested. 4. A relatively high ecdysone titer of 7 CU/g is measured in newly deposited eggs. The hormone is presumably of maternal origin. Subsequent to blastokinesis the hormone content increases dramatically up to about 180 CU/g, apparently due to endocrine function of the embryo. Oenocytes are proposed as the source of ecdysone during late embryonic development. 5. The function of ecdysone during early and advanced embryogenesis, especially in view of "embryonic molts", is discussed.

Animals↗
PubMed1978

Cytochemistry and x-ray microprobe analysis of the midgut of Tomocerus minor lubbock (insecta, collembola) with special reference to the physiological significance of the mineral concretions.

Histochemical and cytochemical analyses have been made on the mineral concretions within the midgut cells of Tomocerus minor. The classical histochemical methods are not specific and precise enough and have been supplemented with cytochemical techniques on ultrathin sections. The most interesting of these was the K-pyroantimonate technique combined with glutaraldehyde-osmium fixation. This technique shows the distribution of cations such as Ca++, K+, Mg++ and Na+ on the concentric layers of the concretions. Chloride ions can be detected by means of the silver lactate technique. The action of calcium chelators such as E.D.T.A. shows an important distribution of calcium ions in the concretions. The spectra obtained by electron probe microanalysis from areas of fresh, dried and carbon coated midguts as well as from carbon coated semithin or ultrathin sections reveal the presence of Ca, K, Mg, S, Cl and P principally. Other elements such as aluminium, silicon and manganese have also been detected. Iron is not always present. The chemical and X-ray analytical investigations indicate that the midgut concretions are mainly built up of calcium, potassium, magnesium and sodium phosphates, perhaps associated with chlorides and carbonates. An organic matrix formed by polysaccharides seems to join the different mineral layers. These concretions may be formed within the vesicles of rough endoplasmic reticulum. The midgut cells are highly differentiated and very active in transport. Extensive basal infoldings and apical microvilli as well as lateral membranes are a site of small cationic deposits. The possible pathway of ion transport in the cell and the physiological significance of the concretions are discussed. The principal function of these concretions seems to be the maintenance of the mineral balance and to trap foreign and excess ions.

Aluminum↗
PubMed1977

Specialization of the endoplasmic reticulum in the apex of the midgut cells of Aeshna cyanea (Insecta, Odonata).

Lamellar stacks of cisternae regularly spaced and bound to each other by fine filaments are observed in the apex of midgut cells of Aeshna cyanea. These cisternae are connected with the rough endoplasmic reticulum but are devoid of ribosomes except on their terminal sacs. Their location and their structure, quite different in fed and starved animals, suggest that they are involved in intracellular transport.

Animals↗
PubMed1978

Ultrastructure of pheromone-producing eversible vesicles in males of Chrysopa perla L. (Insecta, Neuroptera).

During courtship, males of Chrysopa perla extrude from the genital aperture two eversible vesicles that bear approximately 50 sclerotized tubercles with a long, apical hair. Ultrastructural study reveals within each tubercle two juxtaposed subunits: a sensory subunit formed by a mechanoreceptor neuron, a glial cell, two enveloping cells, and a glandular subunit consisting of a glandular cell provided with an extracellular reservoir, a duct cell and an enveloping cell. The glandular-cell cytoplasm is characterized by extensive RER, a large amount of SER, probably involved in lipid elaboration, and voluminous myeloid bodies encircling the reservoir. The secretion is released to the outside by a cuticular duct that opens into the side of the tubercle. The function of the mechanoreceptor associated with the glandular subunit is discussed.

Animals↗
PubMed1979

Junctional structures in the metamorphosing midgut of Aeshna cyanea (Insecta, Odonata).

The metamorphosing midgut of Aeshna cyanea is characterized by the successive development of two tissues: the reticulated tissue and the imaginal epithelium. These tissues supply information concerning contacts between cells diverging in their developmental pathways although arising from the same stem cell population. In addition to small desmosomes, which bind reticulated to imaginal cells, the reticulated cells form invaginations into the apex of imaginal epithelial cells. The projections of the reticulated cells have enlarged tips, and numerous microfilaments run longitudinally along the length of these processes. It is suggested that the anchoring projections of these cells delay the casting off of the reticulated tissue into the lumen, and thus allow the development of the imaginal microvilli. These project into the dilated intercellular space filled with a glycoprotein material that separates imaginal and reticulated cells (Andries, 1972).

Animals↗
PubMed1991

Multiple peptide immunoreactivities in the nervous system of Aeschna cyanea (Insecta, Odonata). An immunohistochemical study using antisera to cholecystokinin octapeptide, somatoliberin, vasoactive intestinal peptide, motilin and proctolin.

By use of the indirect immunoperoxidase method, the brain, the suboesophageal ganglion and the corpora cardiaca of the dragonfly Aeschna cyanea have been shown to be immunoreactive to proctolin antiserum and to several mammalian peptide antisera including unsulfated cholecystokinin octapeptide (CCK-8 NS) (Andriès et al. 1989), vasoactive intestinal peptide (VIP), human somatoliberin (hGRF) (Andriès et al. 1984) and motilin antisera. Immunohistochemical studies have been performed on material fixed in a solution of picricacid paraformaldehyde or in Bouin Hollande's sublimate solution. Antisera were applied on alternate sections or, according to the elution-restaining method of Tramu et al. (1978), one after another on the same section. Multiple peptide immunoreactivities appear expressed in the brain and the suboesophageal ganglion. Cells reactive to both hGRF and VIP antisera show also gastrin/CCK-like immunoreactivity and some of them are also detected by motilin antiserum. Besides, some cells immunopositive to CCK-8 NS and motilin antisera do not show hGRF or VIP immunoreactivity. At least, two pairs of protocerebral cells appear immunoreactive to both CCK-8 NS and proctolin antisera. Therefore, the present observations support our previously developed idea (Andriès et al. 1989) that the population of CCK-like cells is heterogenous.

Animals↗