Experiments on Fixation for Electron Microscopy

1963 ◽  
Vol s3-104 (66) ◽  
pp. 155-167
Author(s):  
S. K. MALHOTRA
Keyword(s):  
Electron Microscopy ◽  
Sodium Acetate ◽  
Butyl Methacrylate ◽  
Distilled Water ◽  
Exocrine Cells ◽  
Alkaline Side ◽  
Veronal Buffer ◽  
Tubule Cells ◽  
Test Objects

Michaelis's sodium acetate / sodium veronal buffer is generally used for holding the pH of fixing solutions for electron microscopy at about pH 7.3 to 7.5. The acetate, however, has no buffering action on the alkaline side of neutrality. Experiments were therefore made to study the effect on preservation of cellular constituents when sodium acetate is omitted from Palade's (or its variants) and Luft's fluids. Exocrine cells of the pancreas, convoluted tubule cells of the kidney, and the testes of the mouse were used as test-objects, n-butyl methacrylate (generally partially prepolymerized) and epikote 812 were used for embedding. The preservation visualized in the micrographs did not seem to suggest any marked differences in the quality of fixation from that produced by fixation in Palade's and Luft's fluids. However, there is some evidence that comparable micrographs could be produced by fixation in simple solutions of OsO4 in distilled water and subsequent embedding in suitable media.

Experiments on Fixation for Electron Microscopy

1962 ◽  
Vol s3-103 (61) ◽  
pp. 5-15
Author(s):  
S. K. MALHOTRA
Keyword(s):  
Electron Microscopy ◽  
Proximal Tubule ◽  
Electron Micrographs ◽  
Osmium Tetroxide ◽  
Simple Solution ◽  
Distilled Water ◽  
Exocrine Cells ◽  
Osmium Tetroxide Solution ◽  
Test Objects

The effect of fixation with a simple solution of osmium tetroxide in distilled water was studied by electron microscopy. Exocrine cells of the pancreas and cells of the proximal tubule of the kidney of the mouse were used as test-objects. Partially prepolymerized methacrylate was used for embedding. There did not appear to be any marked disorganization of the cell inclusions. The appearance of the inclusions in the electron micrographs was similar to what is generally seen after fixation with the buffered osmium tetroxide solution of Palade.

Experiments on Fixation for Electron Microscopy

1963 ◽  
Vol s3-104 (65) ◽  
pp. 123-127
Author(s):  
S. K. MALHOTRA
Keyword(s):  
Electron Microscopy ◽  
Acetic Acid ◽  
Osmium Tetroxide ◽  
Proximal Convoluted Tubule ◽  
Mitochondrial Matrix ◽  
Zymogen Granules ◽  
Exocrine Cells ◽  
Acid Ph ◽  
Pancreatic Exocrine ◽  
Tubule Cells

The effect of fixation with acidified solutions of osmium tetroxide (pH 1.5 to 3.5 has been studied on the first (proximal) convoluted tubule cells of the kidney and the pancreatic exocrine cells of the mouse, by electron microscopy. Partially prepolymerized methacrylate was used for embedding. The various membranous structures and the ribosomes retain their individuality even after prolonged fixation in solutions containing 5% acetic acid (pH 1.5). However, the mitochondrial matrix and the ground cytoplasm are not preserved; the zymogen granules are also partially washed out.

Experiments on Fixation for Electron Microscopy 2. Alkalized Osmium Tetroxide

1962 ◽  
Vol s3-103 (63) ◽  
pp. 287-296
Author(s):  
S. K. MALHOTRA
Keyword(s):  
Electron Microscopy ◽  
Osmium Tetroxide ◽  
Potassium Acetate ◽  
Exocrine Cells ◽  
Osmium Tetroxide Solution ◽  
Convoluted Tubules ◽  
Test Objects ◽  
Proximal Convoluted Tubules

The effect of fixation with osmium tetroxide solution, made alkaline by the addition of potassium acetate, was studied by electron microscopy. Exocrine cells of the pancreas and the cells of the first (‘proximal’) convoluted tubules of the kidney of the mouse were used as test-objects. Partially prepolymerized methacrylate was used for embedding. The preservation of the various cell inclusions was similar to what is generally produced after fixation with Palade's buffered osmium tetroxide.

scholarly journals A STUDY OF FIXATION FOR ELECTRON MICROSCOPY

1952 ◽  
Vol 95 (3) ◽  
pp. 285-298 ◽  
Author(s):  
G. E. Palade
Keyword(s):  
Electron Microscopy ◽  
Osmium Tetroxide ◽  
Enzyme Inhibitors ◽  
Morphological Alterations ◽  
Veronal Buffer

Osmium tetroxide fixation of tissue blocks, as usually effected, is preceded by an acidification of the tissue. This acidification is probably responsible for morphological alterations which are notably disturbing in electron microscopy. The acidification and the resulting morphological alterations cannot be prevented by homogenizing the tissue directly in OsO4 solutions or by adding enzyme inhibitors (fluoride, iodoscetamide) to the fixative. Fixation experiments with buffered OsO4 solutions have shown that the appearance of the fixed cells is conditioned by the pH of the fixative. The quality of fixation can be materially improved by buffering the OsO4 solutions at pH 7.3-7.5, The acetate-veronal buffer appeared to be the most favorable of the buffers tested, Because of these findings, 1 per cent OsO4 buffered at pH 7.3-7.5 with acetate-veronal buffer is recommended as an appropriate fixative for electron microscopy.

Variations in Surface Textures of Quartz Sand using Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 494-495
Author(s):  
Eugene J. Amaral
Keyword(s):  
Electron Microscopy ◽  
Glass Industry ◽  
Glass Slide ◽  
Distilled Water ◽  
Early Paleozoic ◽  
Secondary Effects ◽  
Surface Textures ◽  
High Silica ◽  
Sand Deposit ◽  
The U.S

Examination of sand grain surfaces from early Paleozoic sandstones by electron microscopy reveals a variety of secondary effects caused by rock-forming processes after final deposition of the sand. Detailed studies were conducted on both coarse (≥0.71mm) and fine (=0.25mm) fractions of St. Peter Sandstone, a widespread sand deposit underlying much of the U.S. Central Interior and used in the glass industry because of its remarkably high silica purity.The very friable sandstone was disaggregated and sieved to obtain the two size fractions, and then cleaned by boiling in HCl to remove any iron impurities and rinsed in distilled water. The sand grains were then partially embedded by sprinkling them onto a glass slide coated with a thin tacky layer of latex. Direct platinum shadowed carbon replicas were made of the exposed sand grain surfaces, and were separated by dissolution of the silica in HF acid.

Scanning Electron Microscopy-cuticular Lesions on the Roundworm Ascaris Suum

1970 ◽  
Vol 28 ◽  
pp. 114-115
Author(s):  
P. A. Madden ◽  
W. R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Freeze Drying ◽  
Room Temperature ◽  
Secondary Electron ◽  
Distilled Water ◽  
Freeze Dried ◽  
Silver Paint ◽  
To Come ◽  
Scanning Electron

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.

Reconstruction of Two-Dimensional Projections of GP 32*I

1981 ◽  
Vol 39 ◽  
pp. 38-39
Author(s):  
H.A. Cohen ◽  
W. Chiu ◽  
J. Hosoda
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Uranyl Acetate ◽  
Distilled Water ◽  
Acetate Solution ◽  
Two Dimensional ◽  
Parent Molecule ◽  
T4 Bacteriophage ◽  
Electron Imaging ◽  
Better Than

GP 32 (molecular weight 35000) is a T4 bacteriophage protein that destabilizes the DNA helix. The fragment GP32*I (77% of the total weight), which destabilizes helices better than does the parent molecule, crystallizes as platelets thin enough for electron diffraction and electron imaging. In this paper we discuss the structure of this protein as revealed in images reconstructed from stained and unstained crystals.Crystals were prepared as previously described. Crystals for electron microscopy were pelleted from the buffer suspension, washed in distilled water, and resuspended in 1% glucose. Two lambda droplets were placed on grids over freshly evaporated carbon, allowed to sit for five minutes, and then were drained. Stained crystals were prepared the same way, except that prior to draining the droplet, two lambda of aqueous 1% uranyl acetate solution were applied for 20 seconds. Micrographs were produced using less than 2 e/Å2 for unstained crystals or less than 8 e/Å2 for stained crystals.

The Current Situation in Chemical Stabilization of Biological Materials

1972 ◽  
Vol 30 ◽  
pp. 132-133
Author(s):  
John H. Luft
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Osmium Tetroxide ◽  
Molecular Level ◽  
Cross Linking ◽  
Chemical Stabilization ◽  
Specimen Preparation ◽  
Sufficient Condition ◽  
Radio Telescopes

With information processing devices such as radio telescopes, microscopes or hi-fi systems, the quality of the output often is limited by distortion or noise introduced at the input stage of the device. This analogy can be extended usefully to specimen preparation for the electron microscope; fixation, which initiates the processing sequence, is the single most important step and, unfortunately, is the least well understood. Although there is an abundance of fixation mixtures recommended in the light microscopy literature, osmium tetroxide and glutaraldehyde are favored for electron microscopy. These fixatives react vigorously with proteins at the molecular level. There is clear evidence for the cross-linking of proteins both by osmium tetroxide and glutaraldehyde and cross-linking may be a necessary if not sufficient condition to define fixatives as a class.

Characterization of homoepitaxial diamond films by Electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 880-881
Author(s):  
D.P. Malta ◽  
S.A. Willard ◽  
R.A. Rudder ◽  
G.C. Hudson ◽  
J.B. Posthill ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Surface Defects ◽  
Substrate Surface ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Large Degree ◽  
Rf Plasma ◽  
Semiconducting Diamond

Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. A major goal of current device-related diamond research is to achieve a high quality epitaxial film on an inexpensive, readily available, non-native substrate. One step in the process of achieving this goal is understanding the nucleation and growth processes of diamond films on diamond substrates. Electron microscopy has already proven invaluable for assessing polycrystalline diamond films grown on nonnative surfaces.The quality of the grown diamond film depends on several factors, one of which is the quality of the diamond substrate. Substrates commercially available today have often been found to have scratched surfaces resulting from the polishing process (Fig. 1a). Electron beam-induced current (EBIC) imaging shows that electrically active sub-surface defects can be present to a large degree (Fig. 1c). Growth of homoepitaxial diamond films by rf plasma-enhanced chemical vapor deposition (PECVD) has been found to planarize the scratched substrate surface (Fig. 1b).

The annealed (0001) α-alumina surface and its influence on thin-film growth

1995 ◽  
Vol 53 ◽  
pp. 336-337
Author(s):  
Michael W. Bench ◽  
Paul G. Kotula ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
Surface Energy ◽  
Film Growth ◽  
Thin Film Growth ◽  
Energy Calculations ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Low Energy Electron ◽  
Surface Nature

The growth of semiconductors, superconductors, metals, and other insulators has been investigated using alumina substrates in a variety of orientations. The surface state of the alumina (for example surface reconstruction and step nature) can be expected to affect the growth nature and quality of the epilayers. As such, the surface nature has been studied using a number of techniques including low energy electron diffraction (LEED), reflection electron microscopy (REM), transmission electron microscopy (TEM), molecular dynamics computer simulations, and also by theoretical surface energy calculations. In the (0001) orientation, the bulk alumina lattice can be thought of as a layered structure with A1-A1-O stacking. This gives three possible terminations of the bulk alumina lattice, with theoretical surface energy calculations suggesting that termination should occur between the Al layers. Thus, the lattice often has been described as being made up of layers of (Al-O-Al) unit stacking sequences. There is a 180° rotation in the surface symmetry of successive layers and a total of six layers are required to form the alumina unit cell.

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