The Light Microscope as an Optical Diffractometer

1967 ◽  
Vol 2 (2) ◽  
pp. 163-168
Author(s):  
J. G. GALL
Keyword(s):  
Electron Microscope ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Image Plane ◽  
Optical Diffraction ◽  
Conventional Light Microscope

The analysis of electron micrographs by optical diffraction was introduced recently by Klug & Berger (1964). Their experiments were conducted with a special diffractometer designed for use with diffracting masks up to several inches in diameter. A method is described here for using a conventional light microscope as an optical diffractometer which can accept masks up to 5 mm in diameter. A 100-µ electron-microscope aperture is used as a pinhole source of illumination, and the micrograph to be studied is introduced above the objective. The diffraction pattern produced by the micrograph appears in the usual image plane of the microscope within the eyepiece.

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

scholarly journals ELECTRON MICROSCOPE STUDIES ON THE DICTYOSOMES AND ACROBLASTS IN THE MALE GERM CELLS OF THE CRICKET

1956 ◽  
Vol 2 (4) ◽  
pp. 123-128 ◽  
Author(s):  
H. W. Beams ◽  
T. N. Tahmisian ◽  
R. L. Devine ◽  
Everett Anderson
Keyword(s):  
Electron Microscope ◽  
Golgi Apparatus ◽  
Electron Micrographs ◽  
Germ Cells ◽  
Light Microscope ◽  
Golgi Body ◽  
Duplex Structure ◽  
Male Germ Cells ◽  
Secondary Spermatocyte ◽  
A Chain

The dictyosome (Golgi body) in the secondary spermatocyte of the cricket appears in electron micrographs as a duplex structure composed of (a) a group of parallel double-membraned lamellae and (b) a group of associated vacuoles arranged along the compact lamellae in a chain-like fashion. This arrangement of ultramicroscopic structure for the dictyosomes is strikingly comparable to that described for the Golgi apparatus of vertebrates. Accordingly, the two are considered homologous structures. Associated with the duplex structure of the dictyosomes is a differentiated region composed of small vacuoles. This is thought to represent the pro-acrosome region described in light microscope preparations. In the spermatid the dictyosomes fuse, giving rise to the acroblast. Like the dictyosomes, the acroblasts are made up of double-membraned lamellae and associated vacuoles. In addition, a differentiated acrosome region is present which, in some preparations, may display the acrosome vacuole and granule. Both the dictyosomes and acroblasts are distinct from mitochondria.

The Ultra-fine Structure of Lipid Globules in the Neurones of Helix aspersa

1958 ◽  
Vol s3-99 (46) ◽  
pp. 279-284
Author(s):  
J.T. Y. CHOU ◽  
G. A. MEEK
Keyword(s):  
Methylene Blue ◽  
Fine Structure ◽  
Electron Microscope ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Helix Aspersa

The three kinds of lipid globules recognizable in the living neurones of Helix aspersa have been examined under the electron microscope. The globules of the kind that can be stained blue with methylene blue during life are seen in electron micrographs as spheres or spheroids, with concentric lamination, after calcium-osmium fixation. After fixation with sucrose-osmium laminated crescentic bodies are seen instead; these appear to be formed by distortion of the ‘blue’ globules. The yellow globules contain electrondense material, and sometimes appear reticular. It is possible that the yellow globules may originate by transformation of some of the ‘blue’ globules. The colourless globules generally appear as crenated objects; this appearance may be a shrinkage artifact. Apart from the mitochondria and the three kinds of lipid globules described, no other object large enough to be identified with the light microscope has been seen in the cytoplasm.

scholarly journals STUDIES ON INFLAMMATION

1961 ◽  
Vol 11 (3) ◽  
pp. 571-605 ◽  
Author(s):  
G. Majno ◽  
G. E. Palade
Keyword(s):  
Endothelial Cells ◽  
Electron Microscope ◽  
Basement Membrane ◽  
Blood Vessels ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Intercellular Junctions ◽  
Supporting Evidence ◽  
Electron Microscopic ◽  
Tracer Particles

The mechanism, whereby histamine and serotonin increase the permeability of blood vessels, was studied in the rat by means of the electron microscope. The drugs were injected subcutaneously into the scrotum, whence they diffused into the underlying (striated) cremaster muscle. An intravenous injection of colloidal HgS was also given, in order to facilitate the identification of leaks by means of visible tracer particles. After intervals varying from 1 minute to 57 days the animals were killed; the cremaster was fixed, embedded in methacrylate, and examined with the electron microscope. One to 12 minutes after the injection, the blood vessels of the smallest caliber (3 to 5 micra as measured on electron micrographs) appeared intact. Numerous endothelial openings were present in blood vessels with a diameter of 7 to 8 micra or more. These gaps were 0.1 to 0.8 micra in width; portions of intercellular junctions were often present in one or both of the margins. The underlying basement membrane was morphologically intact. An accumulation of tracer particles and chylomicra against the basement membrane indicated that the latter behaved as a filter, allowing fluid to escape but retaining and concentrating suspended particulate matter of the size used. Uptake of tracer particles by endothelial vesicles was minimal. Phagocytosis by endothelial cells became more prominent at 3 hours, but as a secondary occurrence; the pericytes were actively phagocytic at all stages. At the 3-hour stage no leaks were found. The changes induced by histamine and serotonin were indistinguishable, except that the latter was more potent on a mole-to-mole basis. In control animals only small accumulations of tracer particles were found in the wall of a number of blood vessels. With regard to the pathogenesis of the endothelial leaks, the electron microscopic findings suggested that the endothelial cells become partially disconnected along the intercellular junctions. Supporting evidence was provided at the level of the light microscope, by demonstrating—in the same preparation—the leaks with appropriate tracer particles1, and the intercellular junctions by the silver nitrate method. The lipid nature of the chylomicron deposits observed in electron micrographs was also confirmed at the level of the light microscope, using cremasters fixed in formalin and stained in toto with sudan red.

The structure of the nematocyst thread and the geometry of discharge in Corynactis viridis Allman

1965 ◽  
Vol 250 (764) ◽  
pp. 131-164 ◽  
Keyword(s):  
Electron Microscope ◽  
Surface Area ◽  
Water Vapour ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Hexagonal Array ◽  
Capsule Wall ◽  
Compact Mass ◽  
Screw Surface ◽  
Flocculent Material

Electron microscope studies reveal that the undischarged nematocyst thread is not (as the light microscope image suggests) a cylinder containing a compact mass of barbs, but a screw, as first shown in the electron micrographs of Bretschneider (1949). In the process of discharge, the screw surface is converted to a cylinder without significant change in surface area. This transformation is markedly anisometric, the length of the thread increasing almost threefold, while the overall increase in diameter is less than 50 %. The screw shape of the undischarged thread is due to the presence of three helical pleats in the membrane; and discharge results in the smoothing out of these. The cavity of the thread is smaller in the undischarged condition—because of the presence of pleats—and is largely filled by the whorls of asymmetrical barbs (three to a whorl); the tips of the barbs are pressed closely together, while their spatulate bases are distributed in open hexagonal array over the pleated surface of the thread. Barbs readily become detached from the surface of the discharged thread, leaving a complex, striated scar. The discharged thread is a slightly tapering tube in holotrichous isorhizas, and the barbs show systematic changes in size and proportions with taper. Electron micrographs show that the cavity of the undischarged thread is filled with a flocculent material, as is the space between the capsule wall and the thread. This material is presumably the highly hygroscopic proteinaceous working substance responsible for the increase in volume of the capsular fluid—at least up to 200 %—on hydration. The undischarged thread and its contents, isolated under anhydrous conditions, are conspicuously hygroscopic and perform movements of elongation and rotation as water vapour is admitted to or removed from the system. The transformation of a membrane in the form of a screw surface to a cylinder, such as occurs in the discharge of the nematocyst thread, is only possible if portions of the membrane in the trough of the screw increase in area, or portions of the pleats decrease in area. The apparent constancy of the area of the thread throughout discharge suggests that both processes may occur.

scholarly journals STRUCTURE AND DEVELOPMENT OF VIRUSES OBSERVED IN THE ELECTRON MICROSCOPE

1956 ◽  
Vol 2 (3) ◽  
pp. 351-360 ◽  
Author(s):  
Councilman Morgan ◽  
Calderon Howe ◽  
Harry M. Rose ◽  
Dan H. Moore
Keyword(s):  
Electron Microscope ◽  
Electron Micrographs ◽  
Nuclear Membrane ◽  
Hela Cells ◽  
Light Microscope ◽  
Thin Sections ◽  
Viral Particles ◽  
Crystalline Aggregates ◽  
Internal Body

Representative viruses of the RI-APC group were observed with the electron microscope in thin sections of infected HeLa cells. The viral particles varied in density, were approximately 60 mµ in diameter and had a center to center spacing when close packed of about 65 mµ. Many of the less dense particles exhibited an internal body averaging 24 mµ in diameter. It was suggested that within the nucleus the virus differentiated from dense granular and reticular material and formed crystals. Disintegration of the crystals and disruption of the nuclear membrane with release of virus into the cytoplasm appeared to occur at any stage. No evidence to suggest development of the virus in the cytoplasm was obtained. It was possible to deduce the structure of the viral crystal from the electron micrographs. The viral particles are packed in a cubic body—centered lattice. Correlative histochemical observations in the light microscope which are now in progress revealed that the crystals and non-crystalline aggregates of virus were strongly Feulgen-positive.

Observations on the origin of Chloroplasts and Mitochondria in the leaf cells of higher plants

1965 ◽  
Vol 13 (2) ◽  
pp. 161 ◽  
Author(s):  
M Vesk ◽  
FV Mercer ◽  
JV Possingham
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Micrographs ◽  
Light Microscope ◽  
Higher Plants ◽  
Mature Leaf ◽  
Mesophyll Cells

The chloroplasts and mitochondria in embryonic and mature mesophyll cells of maize, spinach, and barley were studied by electron microscopy. The observations are discussed in relation to theories of organelle status and origins. Some of the e!ectron micrographs can be interpreted as showing that mitochondria arise from chloroplasts in mature leaf cells, and lend support to the view, based on cinephotomicrographic studies, that interconversions between chloroplasts and mitochondria like bodies occur in living mature leaf cells. In contrast, other electron micrographs can be interpreted as showing that mitochondria do not arise from chloroplasts, and that the cinephotographic observations refer to pre-existing mitochondria that have been enclosed previously by the deformable chloroplast. Electron micrographs of developing cells, in which the number of organelles increases, do not support the possibility of interconversions of organelles in young cells. To the contrary, the data for the young cells suggest that both organelles undergo divisions, supporting the view that the organelles are autonomous bodies. Some of the difficulties of correlating and interpreting electron microscope and light microscope observations of the same events are stressed.

A Scanning Electron Microscope Study of the Frustule Structure of the Freshwater Diatom Melosira Granulata (Ehr.) Ralfs

1973 ◽  
Vol 31 ◽  
pp. 218-219
Author(s):  
W. H. Abbott ◽  
C. O. Pollard
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Microscope Study ◽  
Light Microscope ◽  
Electron Microscope Study ◽  
Scanning Electron Microscope Study ◽  
Scanning Electron ◽  
Conventional Light Microscope ◽  
Freshwater Diatom

Frustules of the freshwater diatom Melosira granulata (Ehr.) Ralfs from a freshwater diatomite of Miocene age and recent frustules of this species from Reelfoot Lake, Tennessee were examined under a scanning electron microscope to determine fine structure generally not seen or poorly seen with the conventional light microscope.The terminology used to describe frustule structure in this study was originated by Hendy.Melosira granulata generally grows in chains of two connected frustules with each frustule containing two valves or halves. The connection between frustules is accomplished by the encasing of the adjacent valves of two frustules by a structure called the girdle (Fig. 1a).

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.

Selective Staining of Acid Mucopolysaccharides By Ruthenium Red

1968 ◽  
Vol 26 ◽  
pp. 38-39
Author(s):  
J. H. Luft
Keyword(s):  
Electron Microscope ◽  
Light Microscopy ◽  
Light Microscope ◽  
Osmium Tetroxide ◽  
Single Cells ◽  
Ruthenium Red ◽  
Collagen Fibers ◽  
Selective Staining ◽  
Pectic Substances ◽  
Solid Tissues

Ruthenium red is one of the few completely inorganic dyes used to stain tissues for light microscopy. This novelty is enhanced by ignorance regarding its staining mechanism. However, its continued usefulness in botany for demonstrating pectic substances attests to selectivity of some sort. Whether understood or not, histochemists continue to be grateful for small favors.Ruthenium red can also be used with the electron microscope. If single cells are exposed to ruthenium red solution, sufficient mass can be bound to produce observable density in the electron microscope. Generally, this effect is not useful with solid tissues because the contrast is wasted on the damaged cells at the block surface, with little dye diffusing more than 25-50 μ into the interior. Although these traces of ruthenium red which penetrate between and around cells are visible in the light microscope, they produce negligible contrast in the electron microscope. However, its presence can be amplified by a reaction with osmium tetroxide, probably catalytically, to be easily visible by EM. Now the density is clearly seen to be extracellular and closely associated with collagen fibers (Fig. 1).

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