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The second meiotic division is described in males of a Lepidoptera species,Phragmatobia fuliginosa (Arctiidae), using transmission electron microscopy of ultrathin sections. Emphasis is on the behaviour of the mitochondria. In secondary spermatocytes in metaphase and anaphase, spherical and egg-shaped mitochondria are scattered throughout the cytoplasm lateral to the spindles. These are—as is common...
Two amorphous allotropes of carbon are investigated. They are distinguished by their plasmon and K-edge spectra as diamond-like carbon and a rather soft form of amorphous carbon, respectively. By computing the difference profile of the normalized valence Compton profiles of amorphous diamond-like carbon and amorphous carbon, differences in the momentum densities of the two media are shown. A simple...
We studied the cytochemical features and the ultrastructural changes in cells of the gastric mucosa in European eel (Anguilla anguilla L.) fed an experimental isocaloric diet that supplied half the optimum amount of protein, and increased carbohydrates. The superficial mucosa cells were identifiable by the shape and distribution of granules containing neutral mucosubstances, which were found together...
Like non-peptidergic transmitters, neuropeptides and their receptors display a wide distribution in specific cell types of the nervous system. The peptides are synthesized, typically as part of a larger precursor molecule, on the rough endoplasmic reticulum in the cell body. In thetrans-Golgi network, they are sorted to the regulated secretory pathway, packaged into so-called large dense-core vesicles,...
Antennae of eight species ofBovicola (Trichodectidae) were studied using light microscopy and scanning electron microscopy. The objective of this study was to report on the common presence and the diversity of shape, in different species, of the ‘pit organs’ at the sensilla coeloconica. Generally, the sensilla coeloconica of the sensillar complex of antennal segment 3 showed the ‘pit organs’ at the...
To evaluate the contribution of multiple scattering in momentum-resolved electron energy-loss spectroscopy, the angular dependence of the intensities of multiple scattering was investigated and compared with elastic and inelastic singlescattering rofiles. From the experimental data the intensity ratio between multiple scattering and elastic scattering is derived. It can be used to estimate the contribution...
Colloidal gold is the most widely used electron dense marker in biological electron microscopy. The development of procedures for making gold particles of very defined sizes has made double or even multiple labelling possible using gold of two or more different sizes. Lately a new type of electron dense marker has been developed consisting of ligand-stabilized metal atom clusters rather than colloidal...
Crystalline bacterial cell surface layers (S-layers) are the outermost cell envelope component of many eubacteria and archaeobacteria. S-layers are composed of a single protein or glycoprotein species and exhibit oblique, square or hexagonal lattice symmetry. Pores passing through these monomolecular arrays show identical size and morphology, and functional groups are aligned in well-defined positions...
Sequential removal of the 33-, 23-, and 16-kDa extrinsic subunits of higher plant photosystem II (PSII) by various salt-washing procedures has been monitored by gel electrophoresis and oxygen evolution activity measurements. Structural changes induced by the subunit removal were followed by electron microscopy in conjunction with image processing of two-dimensional (2-D) crystals of PSII. In addition...
Energy filtering TEM (EFTEM) studies of a fibre-reinforced Ti-6A1-4V alloy designed for use in high temperature aerospace applications have been performed using a Philips CM20 TEM equipped with a Gatan imaging filter. The fibre employs a developmental duplex coating based upon a compliant layer of gadolinium metal and a gadolinium boride reaction layer both deposited by physical vapour deposition...
MDCK cells have been treated with a mixed surfactant at low concentrations to study the induced morphological changes. The most significant change at the light microscope level was the appearance of multiple large vesicles, which increased in size with time, up to ≈40 um in diameter. Vesicle formation was shown to be linked with the uptake of the fluid medium, as judged by the presence of FITC-dextran...
The feasibility and limitations of a 1024 × 1024 slow-scan charge-coupled device (CCD) camera were evaluated for imaging in a 400kV electron cryomicroscope. Catalase crystals and amorphous carbon film were used as test specimens. Using catalase crystals, it was found that the finite (24 μm) pixel size of the slow-scan CCD camera governs the ultimate resolution in the acquired images. For instance,...
Excess point defects are generated in metals during irradiation by high energy particles such as electrons, ions and neutrons. Especially in the case of electron irradiation, the only point defects introduced are vacancies and interstitials. These defects develop to form defect clusters of dislocations, stacking faults and voids; when solutes atoms or impurities are contained in metals, the defects...
Peritoneal mast cells and lymphocytes from mice were placed on graphite supports, fixed in methanol, stained with the new fluorochrome tris(2,2′-bipyridine)ruthenium(II) and microanalysed using scanning electron microscopy (SEM). X-ray microanalysis showed the expected signal of P and S (Kα lines) in emission spectra of lymphocytes and mast cells. The signal of Ru (Lα and Lβ1) overlapped with that...
The purpose of this study was to improve the immunogold labeling of epoxy sections and to increase our knowledge of the mechanism for how antigens become immunolabeled on resin sections. Tissues from pancreas, thyroid and fibrin clots were embedded in an epoxy resin and LR-White. The epoxy mixture was composed and treated in different ways, especially with respect to altered amounts of accelerator...
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