Aperture Dependence of Resolution and Beam Transmission in High-Voltage Tem of Thick Biological Specimens

1976 ◽  
Vol 34 ◽  
pp. 564-565
Author(s):  
Mircea Fotino
Keyword(s):  
Electron Microscopy ◽  
Electron Energy ◽  
High Voltage ◽  
Cross Sections ◽  
Dominant Factor ◽  
Specimen Thickness ◽  
Transmitted Beam ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Half Angle

In standard transmission electron microscopy the image is formed by electrons scattered both elastically and inelastically within the specimen. Their relative contributions to the image quality are determined by electron energy, specimen thickness and vertex half angle a of the collection cone defined by the objective aperture.The cross sections for scattering into a given angle decrease as the electron energy increases to the MeV region (1), and the accompanying increased preponderance of the elastic component results in improved resolution in the image of thin objects.In most biological applications of high-voltage electron microscopy the usual thickness range (0.25-5.0 μn) is such that plural scattering within the specimen becomes the dominant factor for resolution and contrast (e.g.(2)). In particular, increased fractions of electrons are removed from the transmitted beam by scattering outside the collection cone.

Histo-grade diamond knives may be an appropriate tool for high-voltage electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 296-297
Author(s):  
M.E. Rock ◽  
J.A. Anderson ◽  
P.S. Binder
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Stereo Pair ◽  
Specimen Thickness ◽  
Serial Sections ◽  
High Voltage Electron Microscopy ◽  
Thin Sections ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Diamond Knife

High voltage electron microscopy (HVEM) has been employed in various ways (whole mounts of cells stereo pair imaging, axial tomography, and serial sections for reconstruction) to elucidate three dimensional (3-D) ultrastructural data. The increased specimen thickness allows further data analysis unobtainable from ultra-thin sections. HVEM can reduce the number of sections needed in 3-D reconstructiortby approximately ten times over conventional transmission electron microscopy (CTEM). But increasing section thickness also increases wear on the diamond knife used to section. We have compared the serial sections obtained from a histo-grade diamond knife with those from an E.M. grade ultra-knife. Both sets of sections were cut 0.5 μm thick from the same block, and evaluated under the one million volt beam of the HVEM.

The application of three-dimensional tomographic reconstruction methods to high-voltage electron microscopy

1987 ◽  
Vol 45 ◽  
pp. 570-573
Author(s):  
B. F. McEwen ◽  
C. L. Rieder ◽  
M. Radermacher ◽  
R. A. Grassucci ◽  
J. N. Turner ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Three Dimensional ◽  
Depth Of Field ◽  
Specimen Thickness ◽  
High Voltage Electron Microscopy ◽  
Thin Sections ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Reconstruction Methods

High-voltage electron microscopy (HVEM) has considerably increased the thickness limit of biological specimens that can be visualized at high resolution. Because of its increased penetration power, HVEM is potentially the most powerful tool available for obtaining three-dimensional (3D) information concerning the structure of cells. In the past, such information was primarily obtained from serial thin sections or techniques based on surface shadowing, but these methods have severe problems and limitations which can only be overcome by imaging greater depths in the samples (see refs. 1 and 2). HVEM has yet to realize its potential for 3D structural determination because of the confusion arising from the overlap of features at different depths in the sample. Due to the relatively large depth of field, which exceeds the specimen thickness, HVEM (like all electron microscopy) produces an image that is essentially a projection of the sample.

Whole Mount Observation of Cultured Cells

1980 ◽  
Vol 38 ◽  
pp. 802-805 ◽  
Author(s):  
K. Hama
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Image Quality ◽  
High Voltage ◽  
Cultured Cells ◽  
Specimen Thickness ◽  
High Voltage Electron Microscopy ◽  
Cellular Architecture ◽  
Voltage Electron ◽  
Whole Mount

The cellular architecture of cultured cells has been investigated on critical-point dried whole mount preparations with the aid of stereo-high voltage electron microscopy2,4,5. In these preparations, the absence of an embedding material permits an stereoobservation at rather low accelerating voltage1,3. In the present study, whole mount preparations of cultured chick fibroblasts were examined in the electron microscope operated at 100 KV, 200 KV, 500 KV, 750 KV and 1,000 KV to investigate the voltage dependency of the usable specimen thickness and of the image quality at different specimen thickness.

High-voltage electron microscopy of capillary endothelial vesicles

1983 ◽  
Vol 41 ◽  
pp. 470-471
Author(s):  
Roger C. Wagner ◽  
Candy S. Robinson
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Cross Sections ◽  
Three Dimensional ◽  
Capillary Wall ◽  
Diaphragm Muscle ◽  
High Voltage Electron Microscopy ◽  
Blood Capillaries ◽  
Voltage Electron ◽  
High Voltage Electron

The three dimensional association of endothelial vesicles must be a determinant in their role in transcapillary transport: Vesicles which shuttle materials across the capillary wall would constitute a discontinuous and nonhydraulically-conductive pathway. Transendothelial channels of fused vesicles would be true pores conducting materials in response to hydrostatic and osmotic pressure gradients across the capillary wall. Sessile, fused clusters of vesicles attached to the plasma membrane but not communicating across the endothelial cell would be inconsequential in transcapillary transport. In order to discern the three dimensional association of vesicles, we have employed high voltage electron microscopy to obtain stereopairs of thick sections through blood capillaries.Whole rats were perfuse-fixed with glutaraldehyde-tannic acid (both 1% w/v) via the left ventricle of the heart. The diaphragm muscle was removed and cut into small strips parallel to the muscle fibers. These were osmicated, dehydrated and embedded in Spurr's medium in an orientation such that cross sections of the capillaries could be taken.

High Voltage Electron Microscopy of Ion-Milled Dental Enamel

1974 ◽  
Vol 32 ◽  
pp. 60-61
Author(s):  
L. D. Ackerman ◽  
S. H. Y. Wei
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Third Molar ◽  
Polarized Light ◽  
Dental Enamel ◽  
Longitudinal Section ◽  
Ion Milling ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.

Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain

1977 ◽  
Vol 35 ◽  
pp. 570-571 ◽  
Author(s):  
Lee D. Peachey ◽  
Clara Franzini-Armstrong
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Three Dimensional ◽  
Biological Tissues ◽  
High Voltage Electron Microscopy ◽  
Transverse Tubular System ◽  
Peroxidase Reaction ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
T System

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.

Radiation-Induced Precipitation at Thin Foil Surfaces in Ni-Be Alloys

1982 ◽  
Vol 40 ◽  
pp. 598-599
Author(s):  
T. Mukai ◽  
T. E. Mitchell
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Electron Irradiation ◽  
High Vacuum ◽  
Thin Foil ◽  
Homogeneous Precipitation ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Radiation Induced

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.

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