scholarly journals ELECTRON MICROSCOPY OF BASOPHILIC STRUCTURES OF SOME INVERTEBRATE OOCYTES

1956 ◽  
Vol 2 (1) ◽  
pp. 93-104 ◽  
Author(s):  
Lionel I. Rebhun
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Cross Sections ◽  
Dense Material ◽  
Continuous Space ◽  
Surf Clam ◽  
Surface View ◽  
Hexagonal Pattern

Highly basophilic plate-shaped regions from oocytes of the surf clam have been examined with the electron microscope. The regions are composed of flat, hollow vesicles perforated by pores arranged, in surface view, in a hexagonal pattern. Cross-sections of this structure show a periodicity consisting of loops (cross-sections of the continuous space within the vesicle) alternating with spaces partly filled with dense material (pores). These structures are shown to resemble closely, the nuclear envelope. Similarities to and differences from basophilic regions of other cells are discussed and it is suggested that the small granules of Palade (38) are represented by granules composing the walls of the annuli of the nuclear envelope and assumed to be present in the annuli of the vesicles. Because of differences in the structure of these regions from basophilic regions of other cells, the name periodic lamellae is suggested since the structures show periodically repeating substructures (annuli) in both cross-sections and surface views.

scholarly journals ELECTRON MICROSCOPY OF BASOPHILIC STRUCTURES OF SOME INVERTEBRATE OOCYTES

1956 ◽  
Vol 2 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Lionel I. Rebhun
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light Microscope ◽  
Entire Body ◽  
Spisula Solidissima ◽  
Hypothetical Model ◽  
Surf Clam

RNA containing yolk nuclei from the surf clam Spisula solidissima have been studied with the light microscope and with the electron microscope. A variety of structures can be seen with both and a correlation can be made between bodies studied with the electron microscope and those studied with the light microscope. The electron microscope shows many of these structures to be composed of double walled lamellae arranged in space, in various ways. The variety of patterns seen with the electron microscope can be satisfactorily explained on the basis of a hypothetical model. The presence of yolk platelets within the yolk nuclei lends support to classical observations on the synthesis of yolk within yolk nuclei or yolk nuclei derivatives. Small granules (about 100 A) are included within the double walled lamellae and their presence probably accounts for the basophilic nature of the entire body. The presence of small granules attached to electron-dense layers relates the yolk nuclei described here to ergastoplasm discussed by others.

scholarly journals Further Observations on the Nuclear Envelope of the Animal Cell

1959 ◽  
Vol 6 (2) ◽  
pp. 147-156 ◽  
Author(s):  
Michael L. Watson
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Cross Section ◽  
Cross Sections ◽  
Nuclear Membrane ◽  
Animal Cell ◽  
Nuclear Surface ◽  
Apparent Discrepancy ◽  
Outer Nuclear Membrane ◽  
Direct Association

The term pore complex is proposed for approximately cylindrical formations which are observed with the electron microscope to penetrate the nuclear envelope of cells. Cross-sections of the pore complex are somewhat annular in shape, but differ in appearance depending upon the level of the cross-section with respect to the nuclear surface. An explanation is offered for the apparent discrepancy between the width of pores in sections perpendicular to the nuclear envelope and the width of cross-sections of the pore complex in tangential sections. Channels associated with the pore complex extend deep into the nucleus. Although crescents and spirals of ribonucleoprotein particles were often seen in the immediate vicinity of the outer nuclear membrane, direct association with the pore complex was not observed. Many examples were found of pores that were not covered by a continuous membrane although the possibility of such a covering in some cases is not precluded.

The Analysis of Pigment Dispersion in Rubber by Means of Light Microscopy, Microradiography, and Electron Microscopy

1962 ◽  
Vol 35 (1) ◽  
pp. 228-249 ◽  
Author(s):  
William M. Hess
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light Microscopy ◽  
Cross Sections ◽  
Tensile Specimen ◽  
Complete Analysis ◽  
Pigment Dispersion ◽  
X Ray ◽  
The Common ◽  
Dispersion Quality

Abstract The significance of these dispersion studies can be summarized as follows: 1) A simple but highly versatile liquid nitrogen freeze technique makes it possible to microtome pigment loaded rubber stocks into thin (0.05–0.1 microns, e.g.) cross sections for examination by means of light microscopy, microradiography or electron microscopy. All of the common elastomers including polybutadiene and silicone rubber have been successfully sectioned for each of these techniques. Thus the state of dispersion can readily be traced from coarse pigment agglomerates, a few hundred microns in size, down to the ultimate particles which can be below 20 millimicrons. 2) Through the use of one of the techniques described or by the coordinated use of all of them (“dispersion in depth”), most dispersion problems can be resolved. A very complete analysis of this type is often necessary to explain pigment effects upon reinforcement. 3) The effects of varied dispersion quality can now be studied directly using special x-ray and electron microscope tensile specimen holders with which small rubber specimens can be examined under strain. Actually these procedures have a greater scope than simply measuring dispersion. The reinforcing capabilities of different pigments in a variety of polymers may be compared by the use of these techniques.

The ultrastructure of chylomicra and of the particles in an artificial fat emulsion

1968 ◽  
Vol 169 (1015) ◽  
pp. 147-152 ◽  
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Electron Microscope ◽  
Olive Oil ◽  
Sodium Citrate ◽  
Corn Oil ◽  
Dense Material ◽  
Fat Emulsion ◽  
Electron Dense Material ◽  
Fresh State

Chylomicra collected from the cannulated thoracic duct of rats fed corn oil or olive oil, and particles of an artificial fat emulsion (Intralipid), were examined with the electron microscope after osmium fixation and Epon embedding. In section, corn oil chylomicra and Intralipid particles show a pale core and an electrondense surface layer; these two zones are thought to represent the triglyceride and phospholipid components respectively. The surface layer measures 50 to 100 Å in width when sectioned transversely. It shows minute interruptions and may be laminated in focal areas. Corn oil chylomicra fixed after storage in a solution of sodium citrate for several days do not differ morphologically from those fixed in the fresh state. In section, olive oil chylomicra show a paler core and a less well-defined surface layer. When fixed in the fresh state, the more electron-dense material is located just beneath the surface of the chylomicron; after storage in citrate the electron-dense material is scattered more peripherally. The findings are discussed in relation to the composition of chylomicra and the changes which the lipids undergo during processing for electron microscopy.

Ultrastructure of wilt syndrome caused by Verticillium dahliae. VII. Correlated light and transmission electron microscope identification of vessel coatings and tyloses

1979 ◽  
Vol 57 (7) ◽  
pp. 822-834 ◽  
Author(s):  
Jane Robb ◽  
J. D. Brisson ◽  
Lloyd Busch ◽  
B. C. Lu
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Cross Sections ◽  
Verticillium Dahliae ◽  
Toluidine Blue ◽  
Sudan Black B ◽  
Transmission Electron ◽  
Blue Reaction ◽  
Secondary Vessels

Thin cross sections of petioles from wilted leaves of chrysanthemums infected with Verticillium dahliae were fixed in glutaraldehyde + FeCl3 and embedded for electron microscopy. Alternate thick (LM) and thin (TEM) sections were cut. The thick sections were stained with (1) the Prussian blue reaction, (2) Sudan black B, (3) toluidine blue O, or (4) Schiff s reagent. Correlated LM and TEM of exactly the same vessels showed that tylosis walls, smooth coating, fibrillar coating, and bubbly coating stained differentially. The tyloses are more abundant than formerly anticipated but are restricted to the primary vessels; fungal cells and coating on vessel walls are confined to smaller secondary vessels.

Quantitative Scanning Transmission Electron Microscopy for the Measurement of Thicknesses and Volumes of Individual Nanoparticles

2009 ◽  
Vol 1184 ◽  
Author(s):  
Helge Heinrich ◽  
Biao Yuan ◽  
Haritha Nukala ◽  
Bo Yao
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Cross Sections ◽  
Scanning Transmission Electron Microscopy ◽  
Sample Thickness ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Individual Nanoparticles

AbstractIn Scanning Transmission Electron Microscopy (STEM) the High-Angle Annular Dark-Field (HAADF) signal increases with atomic number and sample thickness, while dynamic scattering effects and sample orientation have little influence on the contrast. The sensitivity of the HAADF detector for a FEI F30 transmission electron microscope has been calibrated. Additionally, a nearly linear relationship of the HAADF signal with the incident electron current is confirmed. Cross sections of multilayered samples for contrast calibration were obtained by focused ion-beam (FIB) preparation. These cross sections contained several layers with known composition. A database with several pure elements and compounds has been compiled, containing experimental data on the fraction of electrons scattered onto the HAADF detector for each nanometer of sample thickness. Contrast simulations are based on the multi-slice formalism and confirm the differences in HAADF-scattering contrast for the elements and compounds. TEM offers high lateral resolution, but contains little or no information on the thickness of samples. Thickness maps in energy-filtered transmission electron microscopy, convergent-beam electron diffraction and tilt series are so far the only methods to determine thicknesses of particles in a transmission electron microscope. We show that the calibrated HAADF contrast can be used to determine the thicknesses of individual nanoparticles deposited on carbon films. With this information the volumes of nanoparticles with known composition were determined.

Immune electron microscopy of haemocyanins from two southern african whelks

1978 ◽  
Vol 36 (2) ◽  
pp. 158-159
Author(s):  
Linda M. Stannard ◽  
Margaret Lennon
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Outer Ring ◽  
Immune Electron Microscopy ◽  
Intertidal Zones ◽  
Central Belt ◽  
Cape Peninsula ◽  
Circular Contour

Burnupena cincta and Fusus verruculatus are two whelks which inhabit the intertidal zones of the Cape Peninsula shore. Their respiratory pigments, or haemocyanins, are morphologically similar in structure (Figs. 1 and 2) and appear in the electron microscope as short cylindrical rods about 34 nm in diameter and 36 nm high. Viewed side-on the molecules show regular banding suggesting a structure composed of six equidistant rings of sub-units. Occasionally the particles have the appearance of possessing a central “belt” in the position of the 3rd and 4th rows of sub-units. End-on views of the haemocyanin molecules show a circular contour with a dense outer ring and a less dense inner ring in which 10 definite sub-units may frequently be distinguished. A number of molecules display an extra central inner component which appears either as a diffuse plug or as a discrete ring-shaped core ± 8 nm in diameter.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Application of Scanning Electron Microscopy to Medical Research

1969 ◽  
Vol 27 ◽  
pp. 12-13
Author(s):  
J. D. Hutchison
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Medical Research ◽  
Prosthetic Heart Valve ◽  
School Of Medicine ◽  
Transmission Electron ◽  
Definition Of ◽  
Mechanism Of Failure ◽  
The Brain ◽  
Scanning Electron

When the transmission electron microscope was commercially introduced a few years ago, it was heralded as one of the most significant aids to medical research of the century. It continues to occupy that niche; however, the scanning electron microscope is gaining rapidly in relative importance as it fills the gap between conventional optical microscopy and transmission electron microscopy.IBM Boulder is conducting three major programs in cooperation with the Colorado School of Medicine. These are the study of the mechanism of failure of the prosthetic heart valve, the study of the ultrastructure of lung tissue, and the definition of the function of the cilia of the ventricular ependyma of the brain.

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