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.

The application of phase-contrast to the ultra-violet microscope

1950 ◽  
Vol 137 (888) ◽  
pp. 332-339 ◽  
Keyword(s):  
Phase Contrast ◽  
Ultra Violet ◽  
Living Organism ◽  
Selective Absorption ◽  
Wide Range ◽  
Structural Details ◽  
Close Study ◽  
Dark Ground ◽  
Contrast Image ◽  
Selection Of

It has been shown that the phase-contrast principle of Zernike may be applied with advantage to ultra-violet microscopy and that certain advantages follow: ( a ) In the first place, it furnishes a more certain method than dark-ground illumination for the visual selection of a suitable field of view as all structures are more clearly revealed. ( b ) In the second place, it furnishes a new means whereby structural details that give rise to a change of phase in the transmitted radiations may be photographed in contrast, even under conditions when selective absorption does not take place. ( c ) In the third place, it is possible, after having selected a suitable field by means of visual phase-contrast, to photograph the same field in ultra-violet light and then to turn once again to the visual phase-contrast image to make certain that the exposure has not caused damage to a living organism. A series of explanatory photographs has been taken covering a wide range of biological objects. These show that the method is sensitive to minute changes in phase and that the resulting images are characterized by good contrast. Details are revealed that cannot be brought out by normal methods, as will be clear from a close study of the pairs of photographs which accompany this paper. In selecting these it was thought necessary to avoid very fine detail and delicate shades of contrast that would be lost in the process of reproduction.

The application of phase-contrast to the ultra-violet microscope

1950 ◽  
Vol 203 (1075) ◽  
pp. 582-582 ◽  
Keyword(s):  
Phase Contrast ◽  
Ultra Violet ◽  
Living Organism ◽  
Selective Absorption ◽  
Wide Range ◽  
Structural Details ◽  
Close Study ◽  
Dark Ground ◽  
Contrast Image ◽  
Selection Of

It has been shown that the phase-contrast of Zernike may be applied with advantage to ultra-violet microscopy and that certain advantages follow: (а) In the first place, it furnishes a more certain method than dark-ground illumination for the visual selection of a suitable field of view, as all structures are more clearly revealed. (b) In the second place, it furnishes a new means whereby structural details that give rise to a change of phase in the transmitted radiations may be photographed in contrast, even under conditions when selective absorption does not take place. (c) In the third place, it is possible, after having selected a suitable field by means of visual phase-contrast, to photograph the same field in ultra-violet light and then to turn once again to the visual phase-contrast image to make certain that the exposure has not caused damage to a living organism. A series of explanatory photographs has been taken covering a wide range of biological objects. These show that the method is sensitive to minute changes in phase, and that the resulting images are characterized by good contrast. Details are revealed that cannot be brought out by normal methods, as will be clear from a close study of the pairs of photographs which accompany this paper. In selecting these it was thought necessary to avoid very fine detail and delicate shades of contrast that would be lost in the process of reproduction.

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.

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.

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.

The Reduction of Chromatic Aberrations Due to Instrumental Instabilities

1971 ◽  
Vol 29 ◽  
pp. 14-15
Author(s):  
J. S. Lally ◽  
R. Evans
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Usual Practice ◽  
Voltage Electron ◽  
Short Focal Length ◽  
Chromatic Aberrations ◽  
Electron Microscopes

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.

Modification of the Electron Microscope for Investigation of Fully Hydrated Biological Specimens

1969 ◽  
Vol 27 ◽  
pp. 418-419 ◽  
Author(s):  
R. C. Moretz ◽  
D. F. Parsons
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Structural Damage ◽  
Lower Percentage ◽  
Vacuum Drying ◽  
Total Removal ◽  
Total Absence ◽  
Biological Studies ◽  
Electron Microscopes ◽  
Beam Damage

Short lifetime or total absence of electron diffraction of ordered biological specimens is an indication that the specimen undergoes extensive molecular structural damage in the electron microscope. The specimen damage is due to the interaction of the electron beam (40-100 kV) with the specimen and the total removal of water from the structure by vacuum drying. The lower percentage of inelastic scattering at 1 MeV makes it possible to minimize the beam damage to the specimen. The elimination of vacuum drying by modification of the electron microscope is expected to allow more meaningful investigations of biological specimens at 100 kV until 1 MeV electron microscopes become more readily available. One modification, two-film microchambers, has been explored for both biological and non-biological studies.

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

A New High Intensity Grid Cap for RCA-EMU-3 Electron Microscopes

1968 ◽  
Vol 26 ◽  
pp. 316-317
Author(s):  
George Christov ◽  
Bolivar J. Lloyd
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Voltage ◽  
High Intensity ◽  
Electron Gun ◽  
Tungsten Filament ◽  
Fluorescent Screen ◽  
Electron Microscopes ◽  
Pass Through ◽  
Ground Potential

A new high intensity grid cap has been designed for the RCA-EMU-3 electron microscope. Various parameters of the new grid cap were investigated to determine its characteristics. The increase in illumination produced provides ease of focusing on the fluorescent screen at magnifications from 1500 to 50,000 times using an accelerating voltage of 50 KV.The EMU-3 type electron gun assembly consists of a V-shaped tungsten filament for a cathode with a thin metal threaded cathode shield and an anode with a central aperture to permit the beam to course the length of the column. The cathode shield is negatively biased at a potential of several hundred volts with respect to the filament. The electron beam is formed by electrons emitted from the tip of the filament which pass through an aperture of 0.1 inch diameter in the cap and then it is accelerated by the negative high voltage through a 0.625 inch diameter aperture in the anode which is at ground potential.

Remote On-Line Control of a High-Voltage in situ Transmission Electron Microscope with A Rational User Interface

1996 ◽  
Vol 54 ◽  
pp. 384-385
Author(s):  
M.A. O’Keefe ◽  
J. Taylor ◽  
D. Owen ◽  
B. Crowley ◽  
K.H. Westmacott ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
User Interface ◽  
Transmission Electron Microscope ◽  
High Voltage ◽  
Materials Science ◽  
Transmission Electron ◽  
On Line ◽  
Electron Microscopes

Remote on-line electron microscopy is rapidly becoming more available as improvements continue to be developed in the software and hardware of interfaces and networks. Scanning electron microscopes have been driven remotely across both wide and local area networks. Initial implementations with transmission electron microscopes have targeted unique facilities like an advanced analytical electron microscope, a biological 3-D IVEM and a HVEM capable of in situ materials science applications. As implementations of on-line transmission electron microscopy become more widespread, it is essential that suitable standards be developed and followed. Two such standards have been proposed for a high-level protocol language for on-line access, and we have proposed a rational graphical user interface. The user interface we present here is based on experience gained with a full-function materials science application providing users of the National Center for Electron Microscopy with remote on-line access to a 1.5MeV Kratos EM-1500 in situ high-voltage transmission electron microscope via existing wide area networks. We have developed and implemented, and are continuing to refine, a set of tools, protocols, and interfaces to run the Kratos EM-1500 on-line for collaborative research. Computer tools for capturing and manipulating real-time video signals are integrated into a standardized user interface that may be used for remote access to any transmission electron microscope equipped with a suitable control computer.

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