Microbodies and lipid bodies in the hyphal tips of Sclerotinia sclerotiorum

1970 ◽  
Vol 48 (9) ◽  
pp. 1689-1691 ◽  
Author(s):  
Douglas P. Maxwell ◽  
P. H. Williams ◽  
Martha D. Maxwell
Keyword(s):  
Electron Microscope ◽  
Sclerotinia Sclerotiorum ◽  
Phase Contrast ◽  
Agar Medium ◽  
Nile Blue ◽  
Dark Field ◽  
Lipid Bodies ◽  
And Storage ◽  
Hyphal Apex ◽  
Hyphal Tip

Hyphal tips of Sclerotinia sclerotiorum grown on a carboxymethylcellulose agar medium were studied with interference contrast, phase contrast, and dark-field optics and with the electron microscope. Microbodies with hexagonal crystalline inclusions were most abundant in a zone 80–160 μ from the hyphal apex. It is suggested that these bodies are involved in synthetic and storage functions. Lipid bodies were identified by their fluorescence with Nile blue and by their refractivity using dark field optics. They were most abundant in the first 80 μ of the hyphal tip and are thought to originate in this zone. Nuclei were randomly distributed throughout the hyphal tip cell.

On Bridging the Gap in Cytology Between the Light and Electron Microscopes by Some Combined Observations on Snail Neurones

1964 ◽  
Vol s3-105 (70) ◽  
pp. 139-162
Author(s):  
S. M. McGEE-RUSSEL
Keyword(s):  
Electron Microscope ◽  
Phase Contrast ◽  
Nile Blue ◽  
Ultra Violet ◽  
Object A ◽  
Snail Neurones ◽  
Cross Correlations ◽  
Electron Microscopes ◽  
Microscopy Data ◽  
Dark Ground

Discrepancies between observations made with the light microscope only, and with the electron microscope only, can be clarified by using both instruments to study exactly the same section of the same object. A simple technique for doing this is outlined. Direct, phase-contrast, ‘anoptral’ phase-contrast, dark-ground, interference, and ultra-violet microscopy can all be used. When applied to snail neurones this technique of combined observations reveals intracellular organelles which have not previously been differentiated. These organelles are positively identified by criteria appropriate to each instrument. By combined observations it is possible to see the ‘Golgi apparatus’ in preparations stained only with Nile blue, by direct microscopy. Data obtained by combined observations are considered in relation to the previous literature. Unequivocal cross-correlations between the light and the electron microscope go a long way towards explaining past difficulties.

Utilizing Dark Field Electron Microscopy to Produce Lantern Slides

1974 ◽  
Vol 32 ◽  
pp. 116-117
Author(s):  
J. N. Meador ◽  
C. N. Sun ◽  
H. J. White
Keyword(s):  
Electron Microscope ◽  
Electron Micrographs ◽  
Dark Field ◽  
Limiting Factor ◽  
Clinical Laboratories ◽  
Field Electron ◽  
Time Element ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Dark Field Micrographs

The electron microscope is being utilized more and more in clinical laboratories for pathologic diagnosis. One of the major problems in the utilization of the electron microscope for diagnostic purposes is the time element involved. Recent experimentation with rapid embedding has shown that this long phase of the process can be greatly shortened. In rush cases the making of projection slides can be eliminated by taking dark field electron micrographs which show up as a positive ready for use. The major limiting factor for use of dark field micrographs is resolution. However, for conference purposes electron micrographs are usually taken at 2.500X to 8.000X. At these low magnifications the resolution obtained is quite acceptable.

Observation of biological macromolecules using various electron microscopic methods

1978 ◽  
Vol 36 (2) ◽  
pp. 170-171
Author(s):  
Mitsuo Ohtsuki ◽  
Michael Sogard
Keyword(s):  
Electron Microscope ◽  
Phase Contrast ◽  
Image Interpretation ◽  
Density Lipoprotein ◽  
Biological Macromolecules ◽  
Contrast Effects ◽  
Biological Structure ◽  
Electron Microscopic ◽  
Structural Investigations ◽  
Staining Techniques

Structural investigations of biological macromolecules commonly employ CTEM with negative staining techniques. Difficulties in valid image interpretation arise, however, due to problems such as variability in thickness and degree of penetration of the staining agent, noise from the supporting film, and artifacts from defocus phase contrast effects. In order to determine the effects of these variables on biological structure, as seen by the electron microscope, negative stained macromolecules of high density lipoprotein-3 (HDL3) from human serum were analyzed with both CTEM and STEM, and results were then compared with CTEM micrographs of freeze-etched HDL3. In addition, we altered the structure of this molecule by digesting away its phospholipid component with phospholipase A2 and look for consistent changes in structure.

Direct Observation of the Diffusionless β → β + ω Transformation in Titanium Alloys

1971 ◽  
Vol 29 ◽  
pp. 122-123
Author(s):  
N. E. Paton ◽  
D. de Fontaine ◽  
J. C. Williams
Keyword(s):  
Electron Microscope ◽  
Titanium Alloys ◽  
Direct Observation ◽  
Dark Field ◽  
X Ray Diffraction ◽  
Resistivity Measurements ◽  
Selected Area Electron Diffraction ◽  
Ti Alloys ◽  
Thin Foils ◽  
Field Device

The electron microscope has been used to study the diffusionless β → β + ω transformation occurring in certain titanium alloys at low temperatures. Evidence for such a transformation was obtained by Cometto et al by means of x-ray diffraction and resistivity measurements on a Ti-Nb alloy. The present work shows that this type of transformation can occur in several Ti alloys of suitable composition, and some of the details of the transformation are elucidated by means of direct observation in the electron microscope.Thin foils were examined in a Philips EM-300 electron microscope equipped with a uniaxial tilt, liquid nitrogen cooled, cold stage and a high resolution dark field device. Selected area electron diffraction was used to identify the phases present and the ω-phase was imaged in dark field by using a (101)ω reflection. Alloys were water quenched from 950°C, thinned, and mounted between copper grids to minimize temperature gradients in the foil.

The Imaging of Crystal Structures and Crystal Defects

1978 ◽  
Vol 36 (3) ◽  
pp. 207-217
Author(s):  
J.M. Cowley
Keyword(s):  
Electron Microscope ◽  
Crystal Structures ◽  
Phase Contrast ◽  
Crystal Defects ◽  
Atom Density ◽  
Lack Of Information ◽  
Spatial Frequencies

The problem of "understandinq" electron microscope imaqes becomes more acute as the resolution is improved. The naive interpretation of an imaqe as representinq the projection of an atom density becomes less and less appropriate. We are increasinqly forced to face the complexities of coherent imaqinq of what are essentially phase objects. Most electron microscopists are now aware that, for very thin weakly scatterinq objects such as thin unstained bioloqical specimens, hiqh resolution imaqes are best obtained near the optimum defocus, as prescribed by Scherzer, where the phase contrast imaqe qives a qood representation of the projected potential, apart from a lack of information on the lower spatial frequencies. But phase contrast imaqinq is never simple except in idealized limitinq cases.

Resolution in the Scanning Transmission Electron Microscope

1972 ◽  
Vol 30 ◽  
pp. 454-455
Author(s):  
M. G. R. Thomson
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Spherical Aberration ◽  
Signal To Noise Ratio ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Objective Lens ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

The variation of contrast and signal to noise ratio with change in detector solid angle in the high resolution scanning transmission electron microscope was discussed in an earlier paper. In that paper the conclusions were that the most favourable conditions for the imaging of isolated single heavy atoms were, using the notation in figure 1, either bright field phase contrast with β0⋍0.5 α0, or dark field with an annular detector subtending an angle between ao and effectively π/2.The microscope is represented simply by the model illustrated in figure 1, and the objective lens is characterised by its coefficient of spherical aberration Cs. All the results for the Scanning Transmission Electron Microscope (STEM) may with care be applied to the Conventional Electron Microscope (CEM). The object atom is represented as detailed in reference 2, except that ϕ(θ) is taken to be the constant ϕ(0) to simplify the integration. This is reasonable for θ ≤ 0.1 θ0, where 60 is the screening angle.

Removal of inelastically scattered electrons substantially increases phase contrast on frozen-hydrated molecules

1987 ◽  
Vol 45 ◽  
pp. 652-653
Author(s):  
John P. Langmore ◽  
Brian D. Athey
Keyword(s):  
Electron Diffraction ◽  
Phase Contrast ◽  
Low Dose ◽  
Dark Field ◽  
Biological Structure ◽  
Bright Field ◽  
Low Contrast ◽  
Negative Stain ◽  
The Difference ◽  
Better Than

Although electron diffraction indicates better than 0.3nm preservation of biological structure in vitreous ice, the imaging of molecules in ice is limited by low contrast. Thus, low-dose images of frozen-hydrated molecules have significantly more noise than images of air-dried or negatively-stained molecules. We have addressed the question of the origins of this loss of contrast. One unavoidable effect is the reduction in scattering contrast between a molecule and the background. In effect, the difference in scattering power between a molecule and its background is 2-5 times less in a layer of ice than in vacuum or negative stain. A second, previously unrecognized, effect is the large, incoherent background of inelastic scattering from the ice. This background reduces both scattering and phase contrast by an additional factor of about 3, as shown in this paper. We have used energy filtration on the Zeiss EM902 in order to eliminate this second effect, and also increase scattering contrast in bright-field and dark-field.

Towards 1-Ångstrom-resolution STEM

1993 ◽  
Vol 51 ◽  
pp. 996-997
Author(s):  
H.S. von Harrach ◽  
D.E. Jesson ◽  
S.J. Pennycook
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Phase Contrast ◽  
Spherical Aberration ◽  
A Priori ◽  
Dark Field ◽  
Image Resolution ◽  
Objective Lens ◽  
Annular Dark Field ◽  
First Results

Phase contrast TEM has been the leading technique for high resolution imaging of materials for many years, whilst STEM has been the principal method for high-resolution microanalysis. However, it was demonstrated many years ago that low angle dark-field STEM imaging is a priori capable of almost 50% higher point resolution than coherent bright-field imaging (i.e. phase contrast TEM or STEM). This advantage was not exploited until Pennycook developed the high-angle annular dark-field (ADF) technique which can provide an incoherent image showing both high image resolution and atomic number contrast.This paper describes the design and first results of a 300kV field-emission STEM (VG Microscopes HB603U) which has improved ADF STEM image resolution towards the 1 angstrom target. The instrument uses a cold field-emission gun, generating a 300 kV beam of up to 1 μA from an 11-stage accelerator. The beam is focussed on to the specimen by two condensers and a condenser-objective lens with a spherical aberration coefficient of 1.0 mm.

Imaging sub-micron objects with light microscopy: Visualization of the T-4 bacteriophage

1989 ◽  
Vol 47 ◽  
pp. 834-835
Author(s):  
Malcolm Brown ◽  
Reynolds M. Delgado ◽  
Michael J. Fink
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Focal Plane ◽  
Phase Contrast ◽  
Dark Field ◽  
E Coli ◽  
Polystyrene Beads ◽  
Television Camera ◽  
Transmission Electron ◽  
Universal Microscope

While light microscopy has been used to image sub-micron objects, numerous problems with diffraction-limitations often preclude extraction of useful information. Using conventional dark-field and phase contrast light microscopy coupled with image processing, we have studied the following objects: (a) polystyrene beads (88nm, 264nm, and 557mn); (b) frustules of the diatom, Pleurosigma angulatum, and the T-4 bacteriophage attached to its host, E. coli or free in the medium. Equivalent images of the same areas of polystyrene beads and T-4 bacteriophages were produced using transmission electron microscopy.For light microscopy, we used a Zeiss universal microscope. For phase contrast observations a 100X Neofluar objective (N.A.=1.3) was applied. With dark-field, a 100X planachromat objective (N.A.=1.25) in combination with an ultra-condenser (N.A.=1.25) was employed. An intermediate magnifier (Optivar) was available to conveniently give magnification settings of 1.25, 1.6, and 2.0. The image was projected onto the back focal plane of a film or television camera with a Carl Zeiss Jena 18X Compens ocular.

scholarly journals Dark-field microscopy enhance visibility of CD31 endothelial staining

2020 ◽  
Vol 64 (3) ◽  
Author(s):  
Eva Jennische ◽  
Stefan Lange ◽  
Ragnar Hultborn
Keyword(s):  
Phase Contrast ◽  
Scattered Light ◽  
Dark Field ◽  
Light Scatter ◽  
Endothelial Lining ◽  
Microscopy Technique ◽  
Dark Field Microscopy ◽  
Dark Field Illumination ◽  
Normal Human ◽  
Intense Light

A simple dark field microscopy technique was used for visualization of blood vessels in normal human renal tissues and carcinoma. Phase contrast condenser ring apt for high power objectives was combined with a 10x objective in order to create a dark field illumination of the specimens examined. The endothelial lining of the vessels had been stained by using CD31 monoclonal antibodies combined with conventional peroxidase immunohistochemistry. The final DAB addition used for this technique induced an intense light scatter in the dark field microscope. This scattered light originating from the endothelial lining made the walls of the bright vessels easily detectable from the dark background.

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