bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Observation of Dislocation Movements at Elevated Temperatures Using a Heating and Straining Stage
Authors: Ishida Y. , Moritoh F.
Published: June 2020

Dynamic observation of dislocation movements is a direct means of examining proposed deformation mechanisms. Room temperature deformations have been observed dynamically by various authors, but at elevated temperatures no observation has been reported. Various dislocation theories have been proposed on the creep mechanism of metals at elevated temperatures. They disagree to each other even in the basic eharacteristics of the dislocation movements. The dislocation may move either individually or as a group. The motion may be either smooth or intermittent. The dynamic observation is suitable to resolve those basic conflicts.

A heating-straining goniometer stage (Fig. 1) was developed for the experiment. It was mounted in a Hitachi 200KV electron microscope. The foil is pasted between A areas and heated indirectly by a furnace B through a stainless steel tube C. A rapid drying paste Aron α was used in the present experiment. The tube C surrounds the top of the specimen holder.
The Slip Modes in Alloys with the A2 (BC) Heusler-Type Structure
Authors: Strutt P. R. , Rowe G. M.
Published: June 2020

The slip modes in the CsCl type lattice (AB structure) have been considered in detail. Glide on {100} <100> does not involve A.P.B. formation or the creation of stacking faults. In contrast glide on {110} involves displacements that create stacking faults with either <100>, <110> or <111> glide vectors; in addition A.P.B.'s are also formed by ao <110> and ao <111> dislocations. We now consider A2(BC) ternary alloys based on the CsCl lattice where additional ordering of B and C atoms occurs on one of the sub-lattices. Fig. 1 shows a {110} plane where C' is a C-type atom in a subsequent layer. It is evident that both a unit ao [010] and ao [111] translation produce “wrong bonds.” Thus glide in these directions in an A2(BC) alloy must involve either 2ao [010] or 2ao [111] superdislocation pairs. Consequently glide on these systems will be intrinsically more difficult than in a binary alloy where B and C atoms are of the same specie. Since ao <101> is still a unit translation vector in the A2(BC) lattice one would anticipate that {101} <101> slip would not be appreciably more difficult than in the CsCl type lattice.
The Operative Glide Systems in β-NiAl During High Temperature Deformations
Authors: Rowe G. M. , Ingram J. , Strutt P. R.
Published: June 2020

The mechanical properties of β-NiAl, and its operative glide systems have been of interest in recent years (1-4). Strutt, Dodd, & Rowe summarize some of the main findings in a continuation of this work.

The operative glide systems in β-NiAl single crystals were obtained by combined surface slip line observations with the scanning electron microscope, and dislocation diffraction contrast studies using transmission electron microscopy. A method was developed to obtain simulated pictures of dislocations using the two-beam dynamical equations, and considering the effect of elastic anisotropy. The method gave results that are in perfect agreement with those obtained by Head. Since the electron beam was not assumed to be normal to the foil surface the method is more general than that described by Head. However, it is important to note that with the degree of elastic anisotropy in β-NiAl (AF = 3.28) the Burgers vectors of dislocations can be determined with certainty without this procedure providing that a sufficient number of two-beam conditions are employed. This was accomplished with the Philips 300 microscope using the 360° rotation with ±45° tilt goniometer stage.
Electron Metallography of Structures in Crystal Boundaries of Tungsten Wire
Authors: Tufts Charles F.
Published: June 2020

Tungsten lamp wires (0.010 inch diameter) doped with compounds of Al, K and Si to control grain growth at elevated temperatures were studied in “as drawn” and “furnace-annealed” conditions using replication electron microscopy (REM) and transmission electron diffraction contrast microscopy (TEDCM) assisted by selected area electron diffraction (SAED). In addition, thin sections of wire were heated in the goniometer stage of the Philips EM300 electron microscope using a holder that heated the specimen over a temperature range of 20°–1000°C. Rate of increase for specimen temperature was approximately 100°C per minute. Data were obtained by TEDCM and SAED. Purpose of the work was to relate particulate material found in “as drawn” wire to porosity and inclusions distinguishable after elevated-temperature treatment.

Furnace annealing was in vacuum (10-6 torr) at 700°C (30 minutes) or 1500°C (10 minutes or one hour). REM with two-stage Parlodion-carbon replicas was used to observe longitudinal and cross-sectional views of etched specimens.
Recent Studies of the Fine Structure of Carbon Blacks
Authors: Marsh Peter A. , Mullens Troy J. , Price L. D.
Published: June 2020

The paracrystalline nature of the fine structure of carbon blacks was first shown in high resolution phase contrast micrographs by Hess and Ban. These authors described the continuous network of distorted graphite layers within the carbon particles. Measurements of the spacings between these layers has been the subject of our recent work.

The results show that the interplanar spacings have a distribution of sizes in all carbon blacks; for example, the variation in interplanar spacings in furnace blacks ranged from approximately 345 pm (picometers) to 450 pm. In addition, the spacing distribution is independent of both the size of the carbon particles or the degree of interparticle fusion.

Carbon blacks made by the Oil Furnace Process and the Channel Process have the same fine structure, and the distribution of their spacings follows a log-normal distribution pattern. The average spacing for these carbons is 386 ±6 pm. The value obtained by X-ray diffraction methods, approximately 355 pm, is lower because the data is restricted solely to parallel planes.
One Million Direct Magnification Microscopy
Authors: Hugo J. A. , Phillips V. A.
Published: June 2020

A continuing problem in high resolution electron microscopy is that the level of detail visible to the microscopist while he is taking a picture is inferior to that obtainable by the microscope, readily readable on a photographic emulsion and visible in an enlargement made from the plate. Line resolutions, of 2Å or better are now achievable with top of the line 100kv microscopes. Taking the resolution of the human eye as 0.2mm, this indicates a need for a direct viewing magnification of at least one million. However, 0.2mm refers to optimum viewing conditions in daylight or the equivalent, and certainly does not apply to a (colored) image of low contrast and illumination level viewed on a fluorescent screen through a glass window by the dark-adapted eye. Experience indicates that an additional factor of 5 to 10 magnification is needed in order to view lattice images with line spacings of 2 to 4Å. Fortunately this is provided by the normal viewing telescope supplied with most electron microscopes.
Energy Analysis of Small Angle Diffraction Patterns in Aluminum Films
Authors: Pettit R. B. , Silcox J. , Vincent R.
Published: June 2020

One method of investigating the spectral and spatial distribution of the energy lost by the image-forming electrons in an electron microscope uses a dispersive field to form an energy spectrum perpendicular to the length of a narrow entrance slit, mounted below the viewing screen of the microscope. The slit width determines the kind of experiments that can be performed, in that there is generally an upper limit on photographic exposure times due to instrumental instabilities and specimen contamination. A recently built version of this type of instrument uses a Wien filter to form a focussed dispersive image of the electron distribution at the entrance slit. The principle advantage of the system over the Möllenstedt analyser is that the slit can be made much wider (250μm) for the same energy resolution. This gain in intensity has allowed us to examine the energy losses in the smallangle diffraction region around any intense beam in a diffraction pattern.
“Relative Intensities in Single Crystalline ED Patterns”
Authors: Melvin C. D. , Morriss R. H. , Bottoms W. R.
Published: June 2020

A knowledge of the relative intensities of ED spots in a cross-grating pattern is of limited use unless in the interpretation one applies a theory which considers the dynamical interactions among the transmitted and diffracted beams. Even for very thin crystals the kinematic theory (zeroth order approximation used in X-ray diffraction) which neglects all interactions between beams, as well as the 2-beam theory which considers interactions between pairs of beams, are insufficient in predicting relative intensities in electron diffraction. In the present study an attempt was made to correlate intensity measurements from thin (111) microcrystals of gold with theoretical intensities calculated using the scattering matrix formulation of N-beam electron diffraction theory neglecting inelastic scattering. The calculations were performed considering the simultaneous interaction of the transmitted beam and 42 sea ttered beams of types {220}, {422}, {440}, {642}, l/3{422}, and 2/3{422}. The non-integer reflections are attributable to stacking disorder (coherent twinning) in the large (111) planes of the crystal.
Use of Digital Voltmeter for Selected Area Diffraction Calibration
Authors: Grieger G. R.
Published: June 2020

In the interpretation of selected area electron diffraction patterns, the crystal interplanar spacing value d is generally obtained from the formula

(1)

where D is the measured diameter of the diffraction photograph and F is an instrument factor. The value of F is defined as

(2)

where λ is the deBroglie wavelength of the high voltage electron and Le is the effective length of the diffraction camera. The error is d then is

(3)

The error in λ for most modern instruments is quite small, 0.01% or less. The diameter of the ring D can, in general, be read to 0.1 mm which for most patterns is about 0.1%-0.2%. The major source of error in disdue to error in F in general and Le in particular.
The Structures of Adherent and Nonadherent Al2O3 Scales on Fe-25Cr-4Al Alloys
Authors: Tien J. K. , Pettit F. S.
Published: June 2020

It is well documented that the adherence of protective oxide scales to alloy substrates is significantly improved by small alloy additions of such less-common elements as yttrium. This important effect is little understood, however. The lack of structural data is believed to be the major reason for this lack of understanding. Accordingly, we are determining the oxide scale and substrate morphologies of model oxidation resistant alloys. In what follows, we present and discuss the structural details of the nonadherent Al2O3 scale on Fe-25Cr-4Al (wt pct) and the adherent Al2O3 scale on the same alloy with about 0.1 wt pet yttrium or scandium.

The Al2O3 scales are developed by oxidizing these alloys in air at 1200°C. Upon cooling, the nonadherent scale spalls-off as a result of thermal stresses and is immediately ready for examination. The adherent oxide scales had to be extracted by the preferential dissolution of the alloy substrates in a bromine-methanol solution, which does not in any way affect the structure of Al2O3. The scales are then examined by scanning and replication electron microscopy. Figures 1, 2 and 3 are the top (gas surface), side and bottom views of these Al2O3 scales, respectively.
Thoria Particle Growth in Ni-2%ThO2by a Sintering Mechanism
Authors: Kimmel E. R. , Scheithauer W.
Published: June 2020

Good high-temperature mechanical properties exhibited by oxide-dispersion-strengthened metals are strongly dependent on the presence of a cold worked microstructure which is thermally stabilized by fine oxide particles uniformly distributed in the metal matrix. Microstructural features of this nature are produced by subjecting the material to thermal mechanical processing. Such processing has a two-fold purpose—to improve the spatial distribution and to control the size of the dispersion.

The typical state of the dispersion in the hot consolidated P-M plate can best be described as one of fine particles which tend to be highly agglomerated, i.e. a poor spatial distribution. By properly controlling deformation and annealing conditions during thermal mechanical processing of plate to sheet, one can greatly improve the spatial distribution and control the size of the oxide particles. If agglomerates consist of fine particles only in close physical arrangement, deformation will disperse them and thus improve the total spatial distribution.
An Electron Microscopic Study of an Avian Reovirus that Causes Arthritis
Authors: Walker E, R. , Olson N. O. , Friedman M. H.
Published: June 2020

An unidentified virus, responsible for an arthritic-like condition in chickens was studied by electron microscopy and other methods of viral investigation. It was characterized in chorio-allantoic membrane (CAM) lesions of embryonating chicken eggs and in tissue culture as to: 1) particle size; 2) structure; 3) mode of replication in the cell; and 4) nucleic acid type.

The inoculated virus, coated and uncoated, is first seen in lysosomal-like inclusions near the nucleus; the virions appear to be uncoated in these electron dense inclusions (Figure 1), Although transfer of the viral genome from these inclusions is not observable, replicating virus and mature virus crystals are seen in the cytoplasm subsequent to the uncoating of the virions.

The crystals are formed in association with a mass of fibrils 50 to 80 angstroms in diameter and a ribosome-studded structure that appears to be granular endoplasmic reticulum adapted to virus replication (Figure 2). The mature virion (Figure 3) is an icosahedral particle approximately 75 millimicrons in diameter. The inner core is 45 millimicrons, the outer coat 15 millimicrons, and the virion has no envelope.
In Vitro Interactions Between Human Peripheral Macrophages and Rickettsia Mooseri
Authors: Andrese A. P. , Wisseman C. L.
Published: June 2020

Recovery from typhus infection is usually associated with the development of strong immunity to re-infection. An array of immunoglobulins is produced as well as a state of delayed type hypersensitivity. The contribution of the delayed type hypersensitivity to immunity and pathogenesis of disease, though currently under investigation, is unknown. However, it has long been known that passive transfer of serum from an immune subject will confer protection to a non-immune subject, and, hence, humoral antibodies probably play a significant role in immunity. Although serum antibodies display a wide variety of properties, such as agglutination, fixation of complement, opsonization, neutralization of toxic action, etc., studies in our laboratory have shown that these antibodies do not have a direct rickettsiacidal action even when supplemented with complement, lysozyme, etc. Accordingly, it has been postulated that antibodies must act in conjunction with some other component of the defense mechanism such as phagocytic cells, It has been shown in our laboratories that although typhus rickettsiae are readily taken up by macrophage-like cells derived from human peripheral monocytes in cell culture, these cells alone do not destroy the rickettsiae. Instead, the organisms multiply and eventually destroy the cell. However, if the rickettsiae are first exposed to immune serum and are then ingested by these macrophages, they are readily destroyed within the cells.
The Reaction of Brain Structures with OsO4-Zinc-Iodide Stain
Authors: Niklowitz Werner J.
Published: June 2020

After intoxication of rabbits with certain substances such as convulsant agents (3-acetylpyridine), centrally acting drugs (reserpine), or toxic metal compounds (tetraethyl lead) a significant observation by phase microscope is the loss of contrast of the hippocampal mossy fiber layer. It has been suggested that this alteration, as well as changes seen with the electron microscope in the hippocampal mossy fiber boutons, may be related to a loss of neurotransmitters. The purpose of these experiments was to apply the OsO4-zinc-iodide staining technique to the study of these structural changes since it has been suggested that OsO4-zinc-iodide stain reacts with neurotransmitters (acetylcholine, catecholamines).

Domestic New Zealand rabbits (2.5 to 3 kg) were used. Hippocampal tissue was removed from normal and experimental animals treated with 3-acetylpyridine (antimetabolite of nicotinamide), reserpine (anti- hypertensive/tranquilizer), or iproniazid (antidepressant/monamine oxidase inhibitor). After fixation in glutaraldehyde hippocampal tissue was treated with OsO4-zinc-iodide stain and further processed for phase and electron microscope studies.
Ultrastructurc of Subcutaneous Adipose Tissue in Human Neonates
Authors: Alzamora D. , Pardo V. , Monkus E. , Novak M.
Published: June 2020

In vitro studies on the metabolic characteristics of white subcutaneous adipose tissue obtained from human newborns have shown metabolic differences with those in adults. There is an increase in oxygen consumption, CO2 production from labeled glucose, and increased incorporation of palmitic acid into triglycerides. Glycogen content was high in 2 to 4 hours old neonates.

In order to compare the structure of neonate and adult fat, needle biopsies of gluteal subcutaneous adipose tissue were performed in 15 newborns ranging in age from 2 hours to 5 days, and in 4 adults. Tissue fragments and fat cells isolated by collagenase digestion were fixed in 4% osmium tetroxide and 3.5% glutaraldehyde followed by osmium tetroxide in phosphate buffer and embedded in Epon 812.
Unusual Intramitochondrial Inclusions in Hepatocytes in a Case of Hemochromatosis (Seecondary)
Authors: Weide G. C. Vander , Burns W. A.
Published: June 2020

Intramitochondrial granules and inclusions have been widely reported throughout the literature. Many of the inclusions studied fall into the category of crystalline or paracrystalline structures found in mitochondria of normal and pathological cells. It was suggested that the inclusions are formed by alteration of mitochondrial cristae. Amorphous masses and the accumulation of divalent cations in granule form have also been noted in mitochondria under a variety of conditions such as ethionine poisoning, vitamin D deficiency, Gilbert's disease, carbon tetrachloride poisoning, chronic alcoholism, cellular aging as well as changes in the ionic environment of the cell. Normal mitochondrial granules measure approximately 300 A to 500 A and are considered an integral part of the mitochondrion. The intramitochondrial inclusions which are the subject of this report differ from the normal intramitochondrial granule and those inclusions mentioned above in size, density, shape and sub-structure.
Alterations of Gap Junctions in a Human Breast Carcinoma
Authors: Dermer Gerald B. , Kern William H.
Published: June 2020

The cells of solid tumors lack adhesiveness and many cancerous cell types lack intercellular communication. These functional derangements of cell-to-cell interactions in tumor cells may have a structural basis in recent observations that showed a lack or reduction in tight and gap junctions (nexus junctions) in several solid tumors. In an attempt to confirm these findings, gap junctions between human breast carcinoma cells were analyzed and compared to normal breast epithelium by using lanthanum hydroxide as a tracer of intercellular spaces.

Portions of a biopsy from normal breast and a tumor bearing area of a resected breast obtained at the time of surgery were prefixed for 3 hours in a 2.0% glutaraldehyde solution in 0.2M cacodylate buffer containing 1.0% lanthanum nitrate brought to a pH of 7.7 with 0.1N NaOH. The pieces were washed for an additional 24 hours in 0.2M cacodylate buffer containing 1.0% lanthanum nitrate (pH 7.7), postfixed for 1 hour in 1.0% cacodylate buffered OsO4 also containing 1.0% lanthanum nitrate, dehydrated rapidly in graded acetones and embedded in vestopal W.
A Protozoan Model for Golgi-Associated Calcification
Authors: Williams D. C. , Outka D. E.
Published: June 2020

Many studies have shown that the Golgi apparatus is involved in a variety of synthetic activities, and probably no Golgi product is more elaborate than the scales produced by various kinds of phytoflagellates. The formation of calcified scales (coccoliths, Fig. 1,2) of the coccolithophorid phytoflagellates provides a particularly interesting model system for the study of biological mineralization, and the sequential formation of Golgi products.

The coccoliths of Hymenomonas carterae consist of a scale-like base (Fig. 2 and 4, b) with a highly structured calcified (CaCO3) rim composed of two distinct elements which alternate about the base periphery (Fig. 1 and 3, A, B). Each element is enveloped by a sheath-like organic matrix (Fig. 3; Fig. 4, m).
Development of a Multilaminate Core in Microbodies of Euglena gracilis Var. Bacillaris (SM-LI)
Authors: Hanzely L. , Graves L. B. , Molsen D.
Published: June 2020

Ultrastructural surveys have established the microbody as an ubiquitous organelle among the eukaryotes. Examination of Euglena cells, grown on acetate and ethanol and fixed simultaneously with glutaraldehyde-osmium tetroxide, revealed the presence of microbodies morphologically similar to those of other organisms. Moreover, it was shown that these organelles of Euglena possess a multilaminate core or nucleoid apparently not present in other microbodies. The present report concerns these cores and deals specifically with their development.

Microbodies are recognized as organelles bounded by a single membrane, measuring about 0.4 to 0.8 µ in diameter and possessing an electron-dense granular matrix which is distributed evenly throughout the entire organelle (Fig. 1). Often these organelles also show a close association with a single cisterna of the endoplasmic reticulum (Figs. 1, 4, arrows).
Intake of Ferritin byArmillaria melleaHyphae
Authors: Bal Arya K. , Singh Pritam
Published: June 2020

Our earlier study on the fine structure of young hyphae ofArmillaria mellearevealed the presence of numerous invaginations of the plasma-membrane - the so called lomasomes. Functions of these plasma-membrane modifications still remain ambiguous although suggestions have been made as to their involvement in nutrient absorption. With a view to clarifying this functional aspect, ferritin was employed as a marker to trace its path of intake into the hyphal cells.

The fungus was isolated from mycelial fans present under the bark of infected roots ofPicea glauca(Moench). Voss and maintained on 2% Malt agar. Periferal hyphae from 19 days old culture ofA. melleawere exposed to 0.1 ml of a 0.5% aqueous ferritin (Pentax, Inc. 104 ug/ml) solution. The solution was injected into the agar containing the peripheral hyphae. Samples of hyphae were fixed 1-5 seconds after exposure and at 30 minutes, 3 hours, 10 hours, and 24 hours. Fixation, embedding and staining was followed according to the method described by Bal and Singh.
Fine Structure of the Malpighian Tubules of the Mosquito, Culex pipiens
Authors: Clifford Brendan
Published: June 2020

An ultrastructural investigation of the Malpighian tubules of the fourth instar larva of Culex pipiens was undertaken as part of a continuing study of the fine structure of transport epithelia.

Each of the five Malpighian tubules was found to be morphologically identical and regionally undifferentiated. Two distinct cell types, the primary and stellate, were found intermingled along the length of each tubule. The ultrastructure of the stellate cell was previously described in the Malpighian tubule of the blowfly, Calliphora erythrocephala by Berridge and Oschman.

The basal plasma membrane of the primary cell is extremely irregular, giving rise to a complex interconnecting network of basal channels. The compartments of cytoplasm entrapped within this system of basal infoldings contain mitochondria, free ribosomes, and small amounts of rough endoplasmic reticulum. The mitochondria are distinctive in that the cristae run parallel to the long axis of the organelle.
Fine Structure of the Hindgut of Armadillidium Vulgare
Authors: Herold Laura , Vernon G. M. , Witkus E. R.
Published: June 2020

An ultrastructural study of the hepatopancreatic ducts and the hindgut of the terrestrial isopod, Armadillidium vulgare, reveals the presence of a single epithelial cell layer lined with cuticle. The cells of the duct lack the microvilli characteristic of the hepatopancreas and exhibit fewer apical infoldings than the cells of the hindgut. Basal infoldings, on the other hand, are common and relatively deep. Mitochondria are more abundant in the apical region of the cell than in the basal part. Bands of microtubules are present in the peripheral cytoplasm, and most of the microtubules run vertically in the cell from the luminal surface to the base (see fig. 1). Single membrane bounded vesicles of varying size were observed. These bodies contain moderately electron dense granular material. At the luminal surface the lateral membranes of adjacent cells are linked together by septate desmosomes. From the septate desmosome to the base of the cell there are relatively large intercellular spaces alternating with intermediate junctions or zona adherens.
Binding of Transfer RNA to Carbon Films for Electron Microscopy: A Quantitative Approach
Authors: Abermann Reinhard J. , Yoshikami Doju
Published: June 2020

It is essential to establish criteria for the identification of macromolecules studied by electron microscopy. The salt solutions, or (depending on the techniques used) the grain of the shadowing or the staining material or even dirt, may limit the level of confidence with which definitive statements about the macromolecules can be made. With this in mind, we have devised preparatory procedures for the study of one macromolecule, namely tRNA, and investigated its interaction with carbon films. (See also the accompanying paper, Yoshikami and Abermann, these Proceedings.)

Highly purified monomeric mixed tRNA from yeast in a buffer of 0.1 M NaCl, 10 mM MgCl2, 10 mM Na cacodylate, pH 6.6 was used throughout this investigation. Freshly evaporated carbon films were stripped from mica and mounted on grids. tRNA was mounted by floating the grid on a droplet of the tRNA solution. Removal of excess salts and dehydration were done by successive rinses of the grid in ethanol. Ethanol was selected as a rinsing agent since the constituents of the buffer were all soluble in ethanol, and ethanol precipitation and subsequent drying is a well established procedure for concentrating tRNA without destroying its biological activity.
Complementary Replicas of Bacteria
Authors: Demsey Anthony E. , Steere Russell L.
Published: June 2020

The technique of complementary replication has emerged as a necessity for the correct interpretation of biological freeze-etchings. Pioneered by Steere, this technique consists of replicating both ‘halves’ of the fracture plane. By indicating which surfaces are apposed to one another, this process has helped to clear up misconceptions in the interpretation of biological structures.

This technique has been applied to many biological materials; but until now it has not been employed successfully with bacteria because of the difficulty involved in matching complementary ‘halves’ of such a small specimen in a field of so many similar ones. The technique described herein employes avian red blood cells as ‘markers’ in a bacterial sample. By locating matching ‘halves’ of the red blood cells, the complementary bacterial ‘halves’ surrounding them may be readily observed.

Avian red blood cells, used as markers, were fixed in 2% glutaraldehyde and stored in a 40% glycerol solution. A small number of these was added to the pelleted and washed bacterial specimen — untreatedStaphylococcus aureus(ATCC 12600) grown in tryptic soy broth (DIFCO), with pyruvate (0.2%) and uracil (56 mg/liter) added. This mixture of bacteria and red blood cells was placed in hinged specimen holders.
Retinal Elements Revealed by SEM Cryomicrodissection
Authors: McAlear James H. , Germinario Louis , Fucci Robert
Published: June 2020

The scanning electron microscope was used to study the surface of a frozen and then fractured mouse eye. The frozen fractured surface was microdissected in the scanning electron microscope and the freshly fractured surface thus exposed was observed in the microscope.

In order to study the frozen surface it was necessary to develop a cold stage for the Cambridge Stereoscan microscope. This was achieved by fashioning a platform which rests on the standard stage and makes contact with it at three points, two on top and the third below on the back of the stage. It is connected by a braided copper cable to a 1/2-inch by 3-inch brass bar which hangs in front of the stage in the vacuum. The stage functions as a sort of cold block. It is demounted from the microscope and placed in liquid nitrogen and the vitriously frozen sample is attached by means of a set screw in a hole. The cold stage with specimen attached is moved quickly onto the waiting microscope stage. It is necessary to back the specimen chamber with dry N2 gas and to use a liquid N2 trap in the vacuum system in order to minimize ice formation on the stage and to facilitate pumpdown. The stage warms up to the etching temperature (approx -100°C) in 20 to 30 minutes and the ice contamination disappears gradually to reveal the underlying fractured surface. There is no problem in charging up of these samples.
SEM Examination of a Used Diamond Knife
Authors: Black J. Temple
Published: June 2020

Since its introduction by Fernandez-Moran, the diamond knife has gained wide spread usage as a common material for cutting of thin sections of biological and metallic materials into thin films for examination in the transmission electron microscope. With the development of high voltage E.M. and scanning transmission E.M., microtomy applications will become increasingly important in the preparation of specimens. For those who can afford it, the diamond knife will thus continue to be an important tool to accomplish this effort until a cheaper but equally strong and sharp tool is found to replace the diamond, glass not withstanding.

In Figs. 1 thru 3, a first attempt was made to examine the edge of a used (β=45°) diamond knife by means of the scanning electron microscope. Because diamond is conductive, first examination was tried without any coating of the diamond. However, the contamination at the edge caused severe charging during imaging. Next, a thin layer of carbon was deposited but charging was still extensive at high magnification - high voltage settings. Finally, the knife was given a light coating of gold-palladium which eliminated the charging and allowed high magnification micrographs to be made with reasonable resolution.
High Voltage Electron Microscope Study of Living Materials
Authors: Nagata F. , Ishikawa I.
Published: June 2020

During these thirty years, some experiments have been made to observe living materials in an electron microscope. Observation of living things will prove whether biological tissues found in microscope images of sectioned specimens are same as that of living material, and also will enable us to observe organic functions dynamically.

The authers studied the possibility of the observation of living materials. There are three important subjects for the accomplishment; (1) development of environmental cell, (2) specimen injury with electrons irradiation, (3) improvement of image contrast for wet specimen.

It is generally expected that injury to living material will be reduced as an accelerating voltage of irradiating electrons is increased. But neither the rate nor the effects has been studied precisely. In this studies, dry spores of Bacillus megaterium were irradiated with electrons in a specimen chamber of an electron microscope. The accelerating voltage was in the region of 25 to 750 kV and electron quantity was 1x10-7 to 1xl0-2 coulombs/cm2 on a specimen. After the irradiation, the specimens were incubated in the culture fluid and then they were observed with an electron microscope. It is found that as electron number increase, new vegetable cells cease to exist, moreover monsters occur and then spores do not swell. They are similar in tendency at each accelerating voltage but different in amount of irradiation.
Method for Processing of Periodic Images at Reduced Levels of Electron Irradiation
Authors: Glaeser Robert M. , Kuo Ivy , Budinger Thomas F.
Published: June 2020

Meaningful high resolution microscope of specimens that are sensitive to radiation damage is limited in resolution by considerations of statistics and contrast in the image. The product of contrast, C, and resolution, d, must satisfy the inequality

where S/n is the minimum acceptable ratio of real contrast to statistical fluctuations in intensity, f is the fraction of electrons incident upon the specimen that actually contribute to image formation, and Dmin is the minimum dose or exposure that causes structural disorder at the resolution, d. While the value of S/N must be approximately 5 for visual perception of structure, a very much smaller value can be made acceptable by spatial superposition or “averaging” of similar images. In most circumstances this is practical only for objects with a determinable spatial redundancy. We report here on the construction of an experimental system for (1) recording statistically noisy images, (2) determining the image redundancy, and (3) executing the desired spatial averaging.
The Collagenic Molecular Structural Unit of Solid State Complexes
Authors: Richter Kenneth M. , Schilling John A.
Published: June 2020

The structural unit of solid state collagen complexes has been reported by Porter and Vanamee via EM and by Cowan, North and Randall via x-ray diffraction to be an ellipsoidal unit of 210-270 A. length by 50-100 A. diameter. It subsequently was independently demonstrated by us in dog tendon, dermis, and induced complexes. Its detailed morphologic, dimensional and molecular weight (MW) aspects have now been determined. It is pear-shaped in long profile with m diameters of 57 and 108 A. and m length of 263 A. (Fig. 1, tendon, KMnO4 fixation, Na-tungstate; Fig. 2a, schematic of unit in long, C, and x-sectional profiles of its thin, xB, and bulbous, xA portions; Fig. 2b, tendon essentially unmodified by ether and 0.4 N NaOH treatment, Na-tungstate). The unit consists of a uniquely coild cable, c, of ṁ 22.9 A. diameter and length of 2580-3316 A. The cable consists of three 2nd-strands, s, each of m 10.6 A.
On the New Approach of Tannic Acid and Digitonine to the Biological Fixatives
Authors: Mizuhira V. , Futaesaku Y.
Published: June 2020

Radioactive labelled cholesterol is fixed in the tissue as well as labelled other 3β-OH group using saturated digitonine (Digt) in each of the fixative, washing solutions, dehydrating alcohole and propylenoxide. Free metabolites from the 3β-OH group which have already not had 3β-OH structure, can be any more fixed in the tissue. Some of such metabolites may be combined with proteins including lipo- or glyco-proteins. But low molecular proteins should not be fixed with common fixatives, such as aldehydes and OsO4. From such stand-point, we have examined to approach the tannic acid(Tann) for the purpose of protein-fixation, as follows: l) 0.5, 1, 2, 4, 8% Tann and 2.5% glutaraldehyde(Glut) in 0.05M phosphate buffer at pH 6.8, 0°C, for 1.5 to 2 hrs. 2) Fixative-l) containing saturated Digt; 3) After fixation, blocks are washed with phosphate buffer containing 8% sucrose for overnight. 4) Post-fixed in 1% OsO4,(Os) with 0.05M phosphate buffer containing 7% sucrose, at pH 6.8. The blocks stained to deep black(Tann-Protein-Os).
Ultrastructure of Adenohypophyseal Capillaries and Gonadotrophic Cells
Authors: Rosa C. G.
Published: June 2020

During the tenure of a study of the ultrastructural secretory activity of different gonadotrophic cells in the adenohypophysis of the rat, thin section electron microscopy revealed the presence of certain fenestrated-like components projecting from the luminal surface of the capillary endothelial cells (see fig. 1). While all of these structures do not necessarily appear to be the same type of element, some of the components bear a close resemblance to each other. These are comprised of circularly arranged (in cross-section profile) boundaries composed of fenestrated membranes containing a periodicity either equal to or at least very similar to that found in adjacent endothelial fenestrae. Furthermore, some of these structures have been observed in what is apparently a formative stage in which the endothelial fenestrae progressively pull away from the underlying basement membrane forming first a semicircular and ultimately a fully rounded fenestrated-like structure. The presumed genesis of this structure may be followed by studying the unlabeled arrows in fig. 2.
The Formation, Structure, Distribution and Frequency of Nuclear Pores
Authors: Maul G. G.
Published: June 2020

The chromatin of eukaryotic cells is separated from the cytoplasm by a double membrane. One obvious structural specialization of the nuclear membrane is the presence of pores which have been implicated to facilitate the selective nucleocytoplasmic exchange of a variety of large molecules. Thus, the function of nuclear pores has mainly been regarded to be a passive one. Non-membranous diaphragms, radiating fibers, central rings, and other pore-associated structures were thought to play a role in the selective filter function of the nuclear pore complex. Evidence will be presented that suggests that the nuclear pore is a dynamic structure which is non-randomly distributed and can be formed during interphase, and that a close relationship exists between chromatin and the membranous part of the nuclear pore complex.

Octagonality of the nuclear pore complex has been confirmed by a variety of techniques. Using the freeze-etching technique, it was possible to show that the membranous part of the pore complex has an eight-sided outline in human melanoma cells in vitro. Fibers which traverse the pore proper at its corners are continuous and indistinguishable from chromatin at the nucleoplasmic side, as seen in conventionally fixed and sectioned material. Chromatin can be seen in octagonal outline if serial sections are analyzed which are parallel but do not include nuclear membranes (Fig. 1). It is concluded that the shape of the pore rim is due to fibrous material traversing the pore, and may not have any functional significance. In many pores one can recognize a central ring with eight fibers radiating to the corners of the pore rim. Such a structural arrangement is also found to connect eight ribosomes at the nuclear membrane.
Sites of Insulin Action Using Ferritin Labeling
Authors: Silver Burton B. , Nelson Ronald S.
Published: June 2020

Some investigators feel that insulin does not enter cells but exerts its influence in some manner on the cell surface. Ferritin labeling of insulin and insulin antibody was used to determine if binding sites of insulin to specific target organs could be seen with electron microscopy.

Alloxanized rats were considered diabetic if blood sugar levels were in excess of 300 mg %. Test reagents included ferritin, ferritin labeled insulin, and ferritin labeled insulin antibody. Target organs examined were were diaphragm, kidney, gastrocnemius, fat pad, liver and anterior pituitary. Reagents were administered through the left common carotid. Survival time was at least one hour in test animals. Tissue incubation studies were also done in normal as well as diabetic rats. Specimens were fixed in gluteraldehyde and osmium followed by staining with lead and uranium salts. Some tissues were not stained.
Cytopathology of Cardiac Tissue from Daunomycin-Treated Mice
Authors: Liss Robert H. , Cotton Frances A.
Published: June 2020

Daunomycin, an antibiotic used in the clinical management of acute leukemia, produces a delayed, lethal cardiac toxicity. The lethality is dose and schedule dependent; histopathologic changes induced by the drug have been described in heart, lung, and kidney from hamsters in both single and multiple dose studies. Mice given a single intravenous dose of daunomycin (10 mg/kg) die 6-7 days later. Drug distribution studies indicate that the rodents excrete most of a single dose of the drug as daunomycin and metabolite within 48 hours after dosage (M. A. Asbell, personal communication).

Myocardium from the ventricles of 6 moribund BDF1 mice which had received a single intravenous dose of daunomycin (10 mg/kg), and from controls dosed with physiologic saline, was fixed in glutaraldehyde and prepared for electron microscopy.
Effect of Estrogen and Progesterone on Oviduct Smooth Muscle: An Ultrastructural and Cytochemical Study
Authors: Nayak R. K. , Wu A. S. H.
Published: June 2020

The smooth muscle cells of the Fallopian tube, although similar in structure to those of other organs are unique in their response to the action of steroid hormones. To our knowledge few studies have as yet been published about the fine structure of oviduct smooth muscle cell. This fact has induced us to study the influence of estrogen and progesterone upon the ultrastructure of oviduct smooth muscle cells in an attempt to elucidate the action of hormones on the cellular level. Attempts were also made to demonstrate the presence of adenosine triphosphatase (ATP-ase) in these cells at subcellular level.

In Experiment I, prepubertal rabbits (8 weeks old) were given 7 daily intramuscular injections of estradiol benzoate (5 μg/day) and progesterone (2 mg/day) in propylene glycol. In Experiment II, rabbits were ovariectomized at 8 weeks of age and received hormone treatment same as that given in Experiment I, starting 40 days after surgery.
Cytoplasmic Granules in Lymphocytes from Rats Dosed with SK&F 14336-D
Authors: Merrill T. G. , Payne B. J. , Tousimis A. J.
Published: June 2020

Rats given SK&F 14336-D (9-[3-Dimethylamino propyl]-2-chloroacridane), a tranquilizing drug, developed an increased number of vacuolated lymphocytes as observed by light microscopy. Vacuoles in peripheral blood of rats and humans apparently are rare and are not usually reported in differential counts. Transforming agents such as phytohemagglutinin and pokeweed mitogen induce similar vacuoles in in vitro cultures of lymphocytes. These vacuoles have also been reported in some of the lipid-storage diseases of humans such as amaurotic familial idiocy, familial neurovisceral lipidosis, lipomucopolysaccharidosis and sphingomyelinosis. Electron microscopic studies of Tay-Sachs' disease and of chloroquine treated swine have demonstrated large numbers of “membranous cytoplasmic granules” in the cytoplasm of neurons, in addition to lymphocytes. The present study was undertaken with the purpose of characterizing the membranous inclusions and developing an experimental animal model which may be used for the study of lipid storage diseases.
The Differences in Lung Ultrastructural Response of Small and Large Rats to Hyperoxia
Authors: Harrison Gladys A.
Published: June 2020

In the work with oxygen exposed animals, it is readily apparent that there are great differences in the responses of young and old animals. Young rats are far more resistant to oxygen poisoning than are older rats. The younger animals, weighing 90-110 grams (about four weeks old) will live in 100% oxygen at one atmosphere for long periods of time, many surviving for four to six weeks. On the other hand, larger rats, 300-350 grams (12-16 weeks old) live only about three days in the same atmosphere. Obviously, changes must occur at a greater rate, they may be more damaging and may even be different in character.

Rats in the 90-110 gram range and in the 300-350 gram range were exposed for 48 hours to pure oxygen at one atmosphere. The animals were sacrificed, the tissue removed, cut into small blocks and fixed in glutaraldehyde, followed by osmium post-fixation.
Alterations in the Golgi Apparatus of the Breast Gland of the Rat During Pregnancy, Lactation, and Involution
Authors: Murad Tariq M.
Published: June 2020

The mammary gland proliferates and differentiates into its functional state under the influence of various hormones secreted during pregnancy and lactation. Lipid, protein, and carbohydrates, which are important constituents of milk, are known to be secreted by this gland. These substances are synthesized and secreted by the mammary gland in varying concentrations during the gestation and lactation periods. The Golgi apparatus is known to play an important role in the secretory activity of the cells. It is the site of the formation of glycoprotein on the rough surface of the endoplasmic reticulum. In a previous study we were able to show the formation of two types of proteins formed in the epithelial cells of the mammary ductules of pregnant rats that were secreted into the lumina before parturition. The Golgi apparatus played no part in the formation of these particles.
Effects of 5-5'-Diphenyl-2-thiohydantoin (DPTH) and Thyroxine on the Ultrastructure and Chemical Composition of Rat Liver
Authors: Elfont E. A. , Tobin R. B. , Colton D. G. , Mehlman M. A.
Published: June 2020

5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.

Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred dally for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biochemical analyses, while the rest was prefixed in buffered 3.5% glutaraldehyde (390 mOs) and post-fixed in buffered I% OsO4 (376 mOs). Tissues were embedded in Araldite 502 and the sections examined in a Zeiss EM 9S.

Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.
High Voltage Electron Microscopy at Berkeley
Authors: Thomas G.
Published: June 2020

A Hitachi 650kV electron microscope was installed at Berkeley in May 1969. (fig. 1) The fourier resolution test showed 4A° (fig. 2). The research program is centered around three principal advantages which open up new areas of microscopic analyses. These advantages are: a) the gain in transmission power with increasing voltage enabling thick specimens to be examined (up to about 6μ at 650kV depending on material) b) increased stability of roganic solids to radiation damage c) the disappearance voltage effect and fundamental advantages arising from many beam contrast phenomena at high energies.

The increase in transmission enables materials to be examined for which preparation of thin foils is difficult. It also enables specimens to be examined in some cases without any preparation. In the study of fossils it is particularly important to minimize preparation methods since material which has been imbedded in rocks for millions of years are usually brittle and difficult to section. Fig. 3 shows an example of the fibious structure of part of a graptolite specimen, which is 4 × 108 years old. Another example is a study of damage in as-received lunar surface particles (fig. 4).