bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory and Errors in Stereo Electron Microscopy
Authors: Pankratz J. M.
Published: June 2020

It is often desirable in transmission electron microscopy to know the vertical spacing of points of interest within a specimen. However, in order to measure a stereo effect, one must have two pictures of the same area taken from different angles, and one must have also a formula for converting measured differences between corresponding points (parallax) into a height differential.

Assume (a) that the impinging beam of electrons can be considered as a plane wave and (b) that the magnification is the same at the top and bottom of the specimen. The first assumption is good when the illuminating system is overfocused. The second assumption (the so-called “perspective error”) is good when the focal length is large (3 x 107Å) in relation to foil thickness (∼103 Å).
Test on Resolution of Electron Microscope Applied to Thick Specimens
Authors: Koike H.
Published: June 2020

The popularity of the ultra high voltage electron microscope has resulted in a tendency to use thick specimens. R. Uyeda, Y. Kamiya, H. Hashimoto, and V. E. Cosslett reported the results of experiments and calculations determining to what thickness the electron microscope can observe specimens.

Generally, in the case of thick specimens, the resolution in the microscope image depends on chromatic ‘aberration and when the energy distribution of electron beams, after being transmitted through the specimen, is measured, the resolution due to chromatic aberration can be obtained by

In practice, however, resolution depends on the position of the objects (e.g., irregularities such as lattice defects) in the specimen. This may be attributable to phase contrast due to interference phenomena and also attributable to the top-bottom effect pointed out by H. Hashimoto.
Background Gas Reduction in the Electron Microscope
Authors: Buvinger E. A.
Published: June 2020

Today with special stages heating samples in the electron microscope to over 1000°C and resolutions of better than 10 Å required, the reduction of background gases in the microscope is more important than ever. Although the species which contaminate samples—oxygen, water vapor, various hydrocarbons, etc.—cannot be eliminated entirely without excessive time and expense, the equipment and procedures may be optimized so that these species are minimized.

The microscope used for this study was an RCA EMU-3B with a universal chamber providing hot and cold staging. Since the pressure at the sample was of primary interest, an ionization gauge was mounted in the accessory port on the side of the universal chamber. This gauge gave immediate information concerning changes in column pressure which were not readily apparent on the panel meter.
The Use of Field Emission Tips in a Scanning Microscope
Authors: Crewe A. V. , Isaacson M.
Published: June 2020

We have previously described an electron gun which uses a field emission tungsten tip as the source of electrons. In this paper we will discuss the practical aspects of the operation of such tips in an electron gun used in a scanning microscope.

There are essentially three main criteria to be satisfied by these tips:

The tungsten wire must be oriented so that a direction of intense emission is along the axis of the tip.

The axis of the tip must coincide with the optical axis of the microscope.

One must be able to obtain reasonable emission current (about 1 μ amp) at a low enough voltage (1-3 kV).

It is well known that for single crystal tungsten, the planes of intense emission are perpendicular to the (310) and (111) directions (among others). Wire oriented with these directions along the axis can either be bought commercially or it can be cut by electrical discharge machining from a block of single crystal tungsten of known orientation.
Small Angle Electron Scattering From Vacuum Condensed Metallic Films
Authors: Silcox J. , Wade R. H.
Published: June 2020

Recent work has drawn attention to the possibilities that small angle electron scattering offers as a source of information about the micro-structure of vacuum condensed films. In particular, this serves as a good detector of discontinuities within the films. A review of a kinematical theory describing the small angle scattering from a thin film composed of discrete particles packed close together will be presented. Such a model could be represented by a set of cylinders packed side by side in a two dimensional fluid-like array, the axis of the cylinders being normal to the film and the length of the cylinders becoming the thickness of the film. The Fourier transform of such an array can be regarded as a ring structure around the central beam in the plane of the film with the usual thickness transform in a direction normal to the film. The intensity profile across the ring structure is related to the radial distribution function of the spacing between cylinders.
Moire Fringes on Precipitates in Quenched and Aged Beryllium
Authors: Fraikor F. J. , Brewer A. W.
Published: June 2020

A number of investigators have examined moire patterns on precipitate particles in various age-hardening alloys. For example, Phillips has analyzed moire fringes at cobalt precipitates in copper and Von Heimendahl has reported on moire fringes in the system Al-Au. Recently, we have observed moire patterns on impurity precipitates in beryllium quenched in brine from 1000°C and aged at various temperatures in the range of 500-800°C. This heat treatment of beryllium rolled from vacuum cast ingots produces the precipitation of both an fee ternary phase, AlFeBe4, and an hcp binary phase, FeBe11. However, unlike a typical age-hardening alloy, the solute content of this material is low (less than 1000 ppm of Fe and 600 ppm of Al) and hence the total volume fraction of precipitates is small. Therefore there is some difficulty in distinguishing the precipitates and their orientation relationships with the beryllium matrix since the weak precipitate spots generally do not appear on the diffraction patterns.
Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability
Authors: Murr L.E. , Draper A.B.
Published: June 2020

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.

The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.
Oxide Films on Carbide Cutting Tools
Authors: Richman M. H. , Stanislao J.
Published: June 2020

The use of cemented carbide cutting tools for the machining of steels and cast irons depends on the amount of titanium carbide present in the tool. The presence of TiC in addition to the normal WC enhances tool life and allows the use of higher cutting speeds. The original explanation of the mechanism by which TiC improved the cutting performance was made by Skaupy who suggested the presence of a layer of TiO2 which could prevent welding of the chip to the tool. The protective oxide was characterized as Ti2O3 only recently by Stanislao, Richman, and James using reflection electron diffraction. The oxide thickness has been correlated, in a qualitative way, with the various machining parameters such as tool forces, wear, and tool life, but for a quantitative correlation, a method of measuring the actual thickness of the oxide layer had to be developed.
Video real-time imaging of artificial membranes during freeze-drying by cryo-electron microscopy
Authors: Rudolph Alan S. , Price Ronald R.
Published: June 2020

We have employed cryoelectron microscopy to visualize events that occur during the freeze-drying of artificial membranes by employing real time video capture techniques. Artificial membranes or liposomes which are spherical structures within internal aqueous space are stabilized by water which provides the driving force for spontaneous self-assembly of these structures. Previous assays of damage to these structures which are induced by freeze drying reveal that the two principal deleterious events that occur are 1) fusion of liposomes and 2) leakage of contents trapped within the liposome [1]. In the past the only way to access these events was to examine the liposomes following the dehydration event. This technique allows the event to be monitored in real time as the liposomes destabilize and as water is sublimed at cryo temperatures in the vacuum of the microscope. The method by which liposomes are compromised by freeze-drying are largely unknown. This technique has shown that cryo-protectants such as glycerol and carbohydrates are able to maintain liposomal structure throughout the drying process.
A structural overview of the nucleus as derived from CCD-based 3-D optical microscopy
Authors: Paddy Michael R. , Hiraoka Yasushi , Chen Hans , Sedat John W. , Agard David A.
Published: June 2020

The recent past has seen a renaisance in Cell Biology produced by the application of modern molecular tools. Unfortunately, structural adjuncts to this work have been limited by the fact that traditional non-symmetric structural approaches are not generally applicable to structures of the size encountered in Cell Biology. Over the last several years, our laboratory has developed three dimensional electron and optical microscopy methods which, when combined with specific dyes or modern immunocytological techniques, offer a very general approach to structural problems of this size scale.

Our optical microscopy approach uses state-of-the-art digital image aquisition methods and modern computational capabilities to reconstruct three dimensional fluorescence images from a series of two dimensional optical sections. In broad terms, this general approach breaks into three significant elements: 1) aquisition of digital optical microsope images of exceptional quality through the use of a charge coupled device (CCD) imager; 2) computational removal of out of focus information that contaminates each image in the three dimensional data stack; and 3) schemes for visualization and analysis of the resulting three dimensional image.
Fluorescence microscopic analysis of molecular interactions in 3-dimensional samples by means of fluorescence correlation spectroscopy and photobleaching recovery
Authors: Qian Hong , Elson Elliot L.
Published: June 2020

Fluorescence correlation spectroscopy (FCS) and fluoresence photobleaching recovery (FPR) are closely related methods which can be used to measure rates of transport (e.g. diffusion) and of chemical interaction of fluorescent materials. Both methods rely on measurements of fluorescence excited in an open region of the sample. As molecules are transported into or out of the region or their optical properties are changed by chemical interactions, the measured fluorescence changes correspondingly. Once the size of the illuminated region is known, the rates of transport (diffusion, drift, or flow) may be determined from the measured rates of change of fluorescence. There is, however, and important difference in principle between FCS and FPR. The former extracts rate information from measurements of spontaneous concentration fluctuations. The latter measures the relaxation of a macroscopic concentration gradient produced by photobleaching a portion of the fluorophores in the observation region with a brief high intensity light pulse.
Long-term observation of cultured cells by interference-reflection microscopy: near infrared illumination and Y-contrast image processing
Authors: Zand M. S. , Albrecht-Buehler G.
Published: June 2020

Analysis of dynamic changes in cell-substratum adhesion patterns during cell locomotion requires continuous, extended observation of single living cells. To date, interference-reflection microscopy (IRM) is the only method available to visualize cell -substratum adhesions in vitro. This method uses 1% of the incident illumination to produce an IRM image, and so far requires use of a high intensity visible light source (400 - 800 nm). However, light of this intensity and spectral range induces marked changes in fibroblast behavior, including cessation of locomotion. Therefore, we developed a method allowing continuous IRM observation of live cells for up to 8 hours, without any observable changes in normal cell behavior, using near infrared illumination (750-1100 nm). In addition, we use Y-contrast image processing of IRM images to create a 3-dimensional relief of the ventral cell surface.

Single locomoting PTK1 cells were observed continuously in IRM with time lapse video recording for periods of up to 8 hours.
Application of solid-phase immune electron microscopy to study physical and stability characteristics of enterically transmitted non-a, non-b hepatitis virus
Authors: Humphrey Charles D. , Cook E. H. , McCaustland Karen A. , Bradley Daniel W.
Published: June 2020

Enterically transmitted non-A, non-B hepatitis (ET-NANBH) is a type of hepatitis which is increasingly becoming a significant world health concern. As with hepatitis A virus (HAV), spread is by the fecal-oral mode of transmission. Until recently, the etiologic agent had not been isolated and identified. We have succeeded in the isolation and preliminary characterization of this virus and demonstrating that this agent can cause hepatic disease and seroconversion in experimental primates. Our characterization of this virus was facilitated by immune (IEM) and solid phase immune electron microscopic (SPIEM) methodologies.

Many immune electron microscopy methodologies have been used for morphological identification and characterization of viruses. We have previously reported a highly effective solid phase immune electron microscopy procedure which facilitated identification of hepatitis A virus (HAV) in crude cell culture extracts. More recently we have reported utilization of the method for identification of an etiologic agent responsible for (ET-NANBH).
Correlated confocal laser scanning microscopy with high-voltage electron microscopy of focal contacts in 3T3 cells stained with napthol blue black
Authors: Paddock S. W. , Cooke P. H.
Published: June 2020

We used the MRC-500 confocal laser scanning microscope (LSM) in the reflecting mode, rather than the fluorescent mode, to produce high-resolution images of cytoskeletal structures in 3T3 cells stained with Napthol Blue Black (NBB). High voltage electron microscopy CHVEM) of the same cells confirmed that structures at the cell/substratum interface imaged with the LSM are “focal contacts,” regions of cell attachment to the substratum.

Swiss 3T3 cells were cultured on Formvar/carbon-coated gold finder grids in Dulbecco's Modified Eagles medium containing 10% calf serum in saturated humidity and 10% CO2at 37°C. Preconfluent cultures growing on the grids were fixed in a detergent/glutaraldehyde fixative for 10 minutes, stained with 0.2% NBB in methanol/acetic acid/water for 30 minutes, rinsed several times in distilled water, mounted in simple chambers in distilled water and examined in the LSM operated in the reflecting mode.
A new cryofixation device (CF 100)
Authors: Livesey S.A. , Linner J.G. , Piunno C.
Published: June 2020

The aim of this project was to develop an ultrarapid cooling device which optimized the parameters of metal mirror cryofixation, minimized operator dependence and was configured for cost efficient and low maintenance operation.

Cooling of the cryogenic surface is accomplished by flow through of liquid nitrogen at 20 PSI to allow attachment directly to a standard liquid nitrogen tank. Cooling time +25 to -185°C is 45 seconds measured with thermocouple bonded to the upper cryogenic surface.

Atmospheric contamination of the cryogenic surface during cooling is prevented by a surrounding vacuum. Precooling of the sample is avoided by reversal of surrounding vacuum by room temperature ultrapure nitrogen gas at the time of sample application. Atmospheric contamination of the cryogenic surface during application of the sample is prevented by the nitrogen atmosphere and functional interaction of shutter retraction and plunger activation.

Bounce of sample is eliminated by sample holder design and use of a pneumatic plunger at selectable PSI to ensure linear force of application.
Correlative Video-Enhanced Light Microscopy High-Resolution TEM
Authors: Lewis J. C. , Jones N. L. , Allen N. S.
Published: June 2020

Allen video-enhanced contrast, differential interference-contrast microscopy (AVEC-DIC) combines high resolution differential interference contrast microscopy of the Zeiss IM35 microscope with a Hamamatsu video camera to obtain images with increased magnification, resolution, contrast and visibility. Through this combination and by capitalizing on light diffraction phenomena, it is possible to visualize subcellular organelles, particles, and structures which are an order of magnitude smaller (0.01 μm) than the normal limits of resolution with light microscopy (0.2 μm). The use of gold “finder” grids mounted on glass coverslips provides the mechanism by which cells after being observed in the video system can be located in the electron microscope. Such a correlative approach allows static ultrastructural features to be associated with cellular dynamics as observed and recorded by video. When the electron microscopy is done using either IVEM, HVEM or conventional TEM at 120 keV and the images recorded as stereo pair micrographs, the AVEC-DIC spatial data can be directly compared to high resolution 3-D data obtained by EM.
Stimulation of non-opsonic phagocytosis in avian respiratory phagocytes
Authors: Caceci T. , Toth T. , Pyle R.H. , Siegel P.B. , Ochs D.
Published: June 2020

Avian respiratory disease costs the U. S. poultry industry millions of dollars per year in lost production. The avian respiratory system, while similar in many ways, differs from that of mammals anatomically, physiologically, and in its response to invasion by infectious agents. One of the least understood components is the variety of cell types collectively referred to as avian respiratory phagocytes (ARP), the first line of defense against invasion. The resident ARP population is normally very low, but numbers increase in response to certain stimuli. We undertook a study to quantify the extent of ARP influx and the degree of increase in phagocytic activity in response to the presence of non-pathogenic Pasteurella multocida. Chickens were stimulated by intratracheal inoculation of P. multocida, and the ARP's collected by lavage of the lungs and air sacs. Control birds were inoculated with vehicle carrying no P. multocida, and then lavaged.
Ultra-High Resolution SEM in a STEM Instrument
Authors: Liu J. , Cowley J. M.
Published: June 2020

In recent years great improvements in the resolution of secondary electron imaging have been made possible by (1) using a high brightness field emission gun and (2) putting the specimen inside the highly excited objective lens pole-pieces in a scanning electron microscope. Hence, a resolution of 0.8 nm of SE images obtained with a 30 kv electron microscope has been claimed and atom-high surface steps have been observed by detecting SE signals. In a STEM instrument the SE signals are collected at the exit surface of the sample. The emitted secondary electrons spiral up around the fringe magnetic field lines of the objective lens before they are collected by the SE detector. Only type I secondary electrons contribute to the image formation signal in this detecting configuration. The collection efficiency may be high due to the effect of the pre-collection magnetic field and the signal-to-noise ratio is good with the use of a field emission gun.
Low-Voltage Accelerating-Voltage SEM Magnification Standard Prototype
Authors: Postek M. T. , Tiberio R. C.
Published: June 2020

The National Bureau of Standards has had a continuing effort for almost a decade to develop feature-size measurement techniques and the associated linewidth standards for the semiconductor industry. Recently, work began on a scanning electron microscope (SEM) based feature-size measurement program specifically aimed at the development and certification of SEM linewidth standards and the associated techniques for their calibration and use.

Primary to the development and use of SEM linewidth measurement standards is the calibration of the magnification of the SEM. The only standard reference material presently available from NBS for calibrating the magnification of the SEM is the NBS SRM 484.1 This standard provides a known pitch between gold lines in a nickel matrix that is traceable to NBS primary standards. This standard has proven useful for many SEM applications and should continue to be useful for some time to come. However, since SRM 484 was developed prior to the recent interest in low accelerating voltage operation for integrated circuit wafer inspection and measurement, this SRM, in its present form, is unsuitable for use in many of the newly introduced SEM measurement instruments.
Toward High-Resolution Low-Voltage SEM
Authors: Shao Zhifeng
Published: June 2020

Recently, low voltage (≤5kV) scanning electron microscopes have become popular because of their unprecedented advantages, such as minimized charging effects and smaller specimen damage, etc. Perhaps the most important advantage of LVSEM is that they may be able to provide ultrahigh resolution since the interaction volume decreases when electron energy is reduced. It is obvious that no matter how low the operating voltage is, the resolution is always poorer than the probe radius. To achieve 10Å resolution at 5kV (including non-local effects), we would require a probe radius of 5∽6 Å. At low voltages, we can no longer ignore the effects of chromatic aberration because of the increased ratio δV/V. The 3rd order spherical aberration is another major limiting factor. The optimized aperture should be calculated as
Some Notes on the History of the STEM
Authors: Crewe Albert V.
Published: June 2020

I have been asked to give a retrospective talk about the STEM, something which I find difficult to do since I have always preferred to look forward, not backward. I keep no diaries or chronology of successes and failures, and even have difficulty providing a publication list. For this reason I will apologize now for any errors or omissions in my account.

In the space available here it is not possible to write down the history of the STEM and I can only provide a brief glimpse into the efforts of so many people but there are some salient points to be made.

The ideas and concepts behind the STEM have their origins in nuclear and high energy physics where the language and terminology is often very different from that which is used in electron microscopy. One of my earliest mistakes was in not recognizing that fact and remaining insensitive to the language of microscopy for too long.
An Electron Histochemical and Ultrastructural Evaluation of Human Nasal Septal Cartilage Grafts Stored in Merthiolate® and Alcide®
Authors: Wasserman Arthur J. , Christiansen David L. , Kato Y. Pedro , Glasgold Alvin J. , Silver Frederick H.
Published: June 2020

Cartilage is used widely in reconstructive surgery. The inaccessiblity of live cartilage homografts and the limited extended survival record of preserved cartilage used as grafts (1) during surgery creates a need to understand the factors related to post-operative graft resorbtion. Structural changes in chemically preserved human nasal septum (HNS) and a decrease in the lower stiffness (2) of these tissues suggest compositional changes. The purpose of this study was to assess the chronic affects of the chemical preservatives MerthiolateR and AlcideR on HNS using S.E.M., T.E.M. and the proteoglycan specific electron dense stain quinolinic blue (QB) (3).

HNS removed during rhinoplasty or after storage at 4 ° C for 6 months in Mertiolate R or AlcideR were diced into 1 mm cubes while immersed in fixative. Either 1.5% glutaraldehyde-4% paraformaldehyde in 0.1 M cacodylate with 4 mM CaCl2, or 2.5% glutaraldehyde in a critical electrolyte solution of 25mM Na acetate-0.3 M MgCl2 with 0.05% QB were used.
Morphological Changes in Tissue-Cultured Cells Due to Variation in Growth Matrices
Authors: Hogan M. E. , DeGaetano D. H. , Klomparens K. L.
Published: June 2020

As the use of isolated cell cultures increases as an experimental model, there has been a proportional increase in the number of matrices used for cell growth support. These matrices vary in shape, texture and porosity, and as a result, affect the cells grown on them.

The ultrastructural characteristics of several of these growth matrices were examined using two cell types chosen for their distinct growth habits. Chinese Hamster Ovary cells and Balb 3T3 Mouse Fibroblasts were grown on flat substrates (glass, tissue culture plastic, Millipore filters) as well as spherical (glass, tissue culture plastic, cross-linked dextran) matrices. Cells were plated maintaining egual densities and growth surface area. Once the majority of the cells reached confluency (approx. one week), the cell morphology on each matrix was examined using scanning electron microscopy and digital analysis of cell attachment area.

Variation in cell shape was dramatic between matrices, being most noticeable between a textured surface (filter, dextran bead), and that of a smooth (glass) surface (Figs. 1 and 2). Even within smooth surfaces, some variation was observed.
Neurofilaments Pack Differently in Different Parts of the Same Axon
Authors: Price R. L. , Lasek R. J. , Katz M. J.
Published: June 2020

Quantifying cytological ultrastructure can reveal subtle but consistent differences in the organization of cytological elements, such as the cytoskeletal polymers. From these differences, it is possible to infer the dynamic mechanisms that contribute to those organizational variations which give cells their regional characteristics (Lasek, 1988). Myelinated axons manifest many regional specializations. Moreover, such axons have a repeating stereotyped pattern of interactions with the numerous Schwann cells that are distributed along their lengths. Within this pattern, certain regional specializations occur repeatedly: nodes of Ranvier, internodal regions with compact simple myelin, and Schmidt-Lanterman (S-L) clefts (i.e., internodal regions where the Schwann cell cytoplasm separates the myelin lamellae). We have quantified neurofilament number and density in these different regions of the axon in order to explore the mechanisms that underlie neuronal shape.

Twenty-eight day old chickens were perfused by cardiac puncture with 3-4 1 of fixative (4% paraformaldehyde, 2% glutaraldehyde, 0.005% CaCl2, in 0.1M cacodylate buffer, pH7.4). The somatic motor branch of the oculomotor nerve was removed and fixed overnight at 4°C, followed by a buffer rinse and lh in 1% OsO4in 0.1M cacodylate at room temperature.
Preliminary investigation of fiber ultrastructure after enzymatic digestion
Authors: Woodward Janet H. , Akin D. E. , Barton F. E.
Published: June 2020

Knowledge on the chemical and physical structure of fiber is essential in determining forage quality. Current methods provide empirical results on fiber using chemical extractants. This paper is a preliminary report on methods to redefine fiber based on physiological (biochemical) procedures. TEM was employed to evaluate the relationship of fiber with specific enzymatic treatments.

A modified AOAC Total Dietary Fiber Determination was used to prepare one group of insoluble fibers from two legumes of different nutritional quality. Three millimeter wedged-shaped leaflet sections of alfalfa (Medicago sativa L.) and 1-76 lespedeza [Sericea cuneata (Dumont)] were incubated stepwise with: (1) heat stable α amylase, pH 6.0, for h at 100°C; (2) protease, pH 7.5, for h at 60°C; and (3) amyloglucosidase, pH 4.5, for h at 60°C. All leaflet sections were retrieved and incubated for 24 h at 37°C with either: (1) 1% (w/v) cellulase in 0.05 M sodium acetate buffer, pH 5.0; (2) 10% (w/v) hemicellulase in 0.05 M acetate buffer, pH 5.5; or (3) 1% cellulase and 10% hemicel1ulase in the acetate buffer.
Correlative electron microscopic study of metallic particle contaminates in tissue adjacent to dental implants: Part I—3 months
Authors: Krizan K. E. , Zeitler D. L. , Dogan A. U. , Madison S.
Published: June 2020

The purpose of this study is to evaluate metallic contaminants in tissue surrounding tapered endodontic endosseous implants (EEI) of two different metallic implants: titanium (Ti) and vitallium (Vi, an alloy comprised of Co, Cr, Ni and Fe). These implants are used to stabilize compromised teeth. Placement followed pulpectomy and drilling to the proper depth and size for the solid implant rods which use the root canal as a pathway to supporting bone. Application of various electron microscopy techniques reveal the visual image and chemical composition of dense particles adjacent to implants as they exit a root apex extending into maxillary and mandibular bone 2-5 mm. Energy dispersive x-ray microanalysis (EDS) of the particles correlated with x-ray fluorescence (XRF) of bulk samples demonstrate different sources of metallic contamination in tissues adjacent to EEI in a primate model. Four cynomolgus monkeys received four EEI in four incisors, eight Ti and eight Vi implants. Three months after the operations the animals were sacrificed and perfused with a fixative.
Dimethyl sulfoxide protection of endotoxin-induced myocardial injury
Authors: Stiers David L. , Brackett Daniel J. , Wilson Michael F.
Published: June 2020

Within the framework of a multi-discipline project, myocardial structure was evaluated utilizing transmission electron microscopy (TEM) to access cellular integrity of the myocardium during endotoxemia. Our initial purpose was to evaluate the early progression of myocardial damage during development of endotoxemia in the conscious, instrumented rat. Since neutrophil activation and/or hypoperfusion resulting in ischemia are potential sources of excess free radical generation which may be the mechanisms for tissue injury during endotoxemia, we also examined the prgtfplive effects of dimethyl sulfoxide (DMSO) on myocardial ultrastructure.

After instrumentation and endotoxin challenge (LD9024 hours), animals were perfused at one, two, or four hours with Karnousky's fixative, and hearts were removed for processing for TEM. The effect of DMSO (6 mg/kg) on the development of endotoxemia was evaluated by intraperitoneal administration 20 min prior to endotoxin challenge. These animals presented typical cardiac, metabolic, and circulatory responses to endotoxin challenge indicative of ultimate lethality.
Ultrastructure Of Thyroid gland of ducks fed methylmercury (CH3HG), cadmium (CD), and lead (PB) in combination
Authors: Bhatnagar M.K. , David L.L. , Jordan S.A. , Prasada Rao P.V.V.
Published: June 2020

Dysfunction of thyroid gland has been noted in animals exposed to CH3Hg1, Cd2,3 and Pb4,5 but the morphologic changes in the thyroid due to heavy metal exposure have not been described. This report describes the ultrastructural alterations in the follicular epithelium of thyroid gland of ducks exposed to CH3Hg, CdCl2 and Pb acetate singly and in combination. Thirty mature female Pekin ducks were divided in 5 groups (Gr) of 6 ducks each and maintained in cages at a room temperature of 21°C with 14 hrs light and 10 dark regimen. The birds were fed ad libitum. Gr 1 received no heavy metal (control), Gr 2 was fed CH3Hg @ 8.0 mg/kg feed, Gr 3 received Cd chloride @ 80.0 mg/kg feed, Gr 4 was fed Pb acetate @ 80.0 mg/kg feed and Gr 5 was fed 8.0 mg CH3Hg, 80.0 mg CdCl2 and 80.0 mg Pb acetate/kg feed simultaneously for 90 days.
Ultrastructure of myoepithelial cell in parotid gland
Authors: Sun C. N.
Published: June 2020

Myoepithelial cells have been observed in the prostate, harderian, apocrine, exocrine sweat and mammary glands. Such cells and their numerous branching processes form basket-like structures around the glandular acini. Their shapes are quite different from structures seen either in spindleshaped smooth muscle cells or skeletal muscle cells. These myoepithelial cells lie on the epithelial side of the basement membrane in the glands. This presentation describes the ultrastructure of such myoepithelial cells which have been found also in the parotid gland carcinoma from a 45-year old patient.

Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4 percent glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1 percent buffered osmium tetroxide for 1 hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate. Ultrastructurally, the pattern of each individual cell showed wide variations.
Fate of thickened perineurial cell basement membrane in a diabetic patient following pancreas transplantation
Authors: Beggs J. L. , Johnson P. C. , Watkins C. J. , Olafsen A. G. , Jones C. P. , Targovnik J.
Published: June 2020

The perineurial sheath of dermal nerves is usually composed of one to several cell layers. Thickening of perineurial cell basement membranes (PCBM) is a common feature in diabetics. Since PCBM thickening may have relevance to the cause of diabetic neuropathy the fate of thickened PCBM following various treatment regimens is of prime importance. In this study, we examined dermal nerves of monozygotic twins discordant for diabetes to determine the effects of pancreas transplantation on PCBM thickness.

Patient History and Methods: This 53 year old diabetic man with an 18 year history of insulin dependency presented with progressive development of retinopathy, nephropathy and neuropathy. Pancreas transplantation (donor Identical twin) was performed to treat diabetic complications. Shortly after transplantation, the patient became normoglycemic and has remained euglycemic for 2 years. Signs and symptoms of diabetic complications improved; nerve conductance in the lower extremities improved. Abdominal skin biopsies were taken from the twins before transplantation and subsequent biopsies (1,2 yr post-transplant) were taken from the diabetic patient.
Permeability of the microcirculation in area postrema of rat
Authors: Ghoneim Shams M. , Faraci Frank M. , Baumbach Gary L.
Published: June 2020

The area postrema is a circumventricular organ in the brain stem and is one of the regions in the brain that lacks a fully functional blood-brain barrier. Recently, we found that disruption of the microcirculation during acute hypertension is greater in area postrema than in the adjacent brain stem. In contrast, hyperosmolar disruption of the microcirculation is greater in brain stem. The objective of this study was to compare ultrastructural characteristics of the microcirculation in area postrema and adjacent brain stem.

We studied 5 Sprague-Dawley rats. Horseradish peroxidase was injected intravenously and allowed to circulate for 1, 5 or 15 minutes. Following perfusion of the upper body with 2.25% glutaraldehyde in 0.1 M sodium cacodylate, the brain stem was removed, embedded in agar, and chopped into 50-70 μm sections with a TC-Sorvall tissue chopper. Sections of brain stem were incubated for 1 hour in a solution of 3,3' diaminobenzidine tetrahydrochloride (0.05%) in 0.05M Tris buffer with 1% H2O2.
Effects of carbamylcholine on chick embryo aggregate retina cell cultures
Authors: Cohen Glenn M. , Ray Radharaman
Published: June 2020

Retinal,cell aggregates develop in culture in a pattern similar to the in ovo retina, forming neurites first and then synapses. In the present study, we continuously exposed chick retinal cell aggregates to a high concentration (1 mM) of carbamylcholine (carbachol), an acetylcholine (ACh) analog that resists hydrolysis by acetylcholinesterase (AChE). This situation is similar to organophosphorus anticholinesterase poisoning in which the ACh level is elevated at synaptic junctions due to inhibition of AChE, Our objective was to determine whether continuous carbachol exposure either damaged cholino- ceptive neurites, cell bodies, and synaptic elements of the aggregates or influenced (hastened or retarded) their development.

The retinal tissue was isolated aseptically from 11 day embryonic White Leghorn chicks and then enzymatically (trypsin) and mechanically (trituration) dissociated into single cells. After washing the cells by repeated suspension and low (about 200 x G) centrifugation twice, aggregate cell cultures (about l0 cells/culture) were initiated in 1.5 ml medium (BME, GIBCO) in 35 mm sterile culture dishes and maintained as experimental (containing 10-3 M carbachol) and control specimens.
Light and electron microscopic investigation of adenohypophyses of germfree, food-restricted, and germfree-food restricted aging, male lobund-wistar rats
Authors: Ilse G. , Kovacs K. , Ryan N. , Sano T. , Stefaneanu L. , Asa S.L. , Snyder D.
Published: June 2020

Germfree state and food restriction have been shown to increase life span and delay tumor occurrence in rats. We report here the histologic, immunocytochemical and electron microscopic findings of adenohypophyses of aging, male Lobund-Wistar rats raised at Lobund Laboratories. In our previous study, the morphologic changes in the adenohypophyses of old rats have been extensively investigated by histology, immunocytochemistry and electron microscopy. Lactotroph adenomas were frequent in Long-Evans and Sprague-Dawley rats, whereas gonadotroph adenomas were frequent in Sprague-Dawley and Wistar rats.

Male Lobund-Wistar rats were divided into four groups: 1) conventional, which were raised under normal non-germfree environment and received food ad libitum; 2) germfree-food ad libitum; 3) conventional environment-food restricted and 4) germfree-food restricted. The adenohypophyses were removed from 6-month-, 18-month- and 30-month-old rats. For light microscopy, adenohypophyses were fixed in formalin and embedded in paraffin.
Hypoxia-induced structural changes in cultured heart cells
Authors: Hawkey L.A. , LeFurgey A. , Wagenknecht B. , Lieberman M.
Published: June 2020

Understanding the mechanisms involved in irreversible cell injury during myocardial ischema is an important step in developing treatments to lessen or prevent damage at the cellular level and /or to speed cell recovery. Establishing the sequence of changes that occur, both ultrastructurally and biochemically, when heart cells suffer oxygen deprivation is necessary in order to reach this understanding. The objective in the current studies is to document the relationships between, and the time dependence of, morphological, ionic and metabolic alterations occurring when cultured heart cells are exposed to hypoxia and substrate depletion.

Embryonic chick myocardial cells were grown as muscle-enriched monolayer cultures for four days. Non-muscle cell cultures were prepared and grown as described previously, for evaluation of the response to hypoxia of the fibroblast component (<10%) of the muscle-enriched cultures. Cultures were then incubated in substrate-free media in an anaerobic chamber (PO2<0.1%) and samples were taken at one hour intervals for biochemical and ultrastructural analyses.
Diagnostic virology in veterinary pathology: techniques for negative staining
Authors: Basgall Edward J. , Scherba Gail , Gelberg Howard B.
Published: June 2020

Negative staining of virus suspensions is the quickest, easiest diagnostic technique currently available to the electron microscopist. Virus sampling and staining from directly collected fluids is inherently rapid, simple, and straightforward. Virions in a sample can be stained directly on a formvar coated grid then examined in a transmission electron microscope (TEM).

The collection, detection, and identification of enteric viruses is more involved. Intestinal contents are often presented in a variety of states, from clear fluid to solid. In a diagnostic setting, a routinely reliable protocol is a necessity for fast, accurate results. Several authors have recommended various techniques for clarifying virus preparations from fecal samples. However, these methods do not inactivate pathogens in the samples. Moreover, a recent report indicates that technical staining parameters of virus staining could influence virus particle integrity. The routine use of 10% neutral buffered formalin (NBF) fixation prior to concentrating and staining virus samples both stabilizes and inactivates the majority of viruses encountered in a diagnostic setting.
Ultrastructural localization of carbohydrate determinants of lipopolysaccharide of coxiella burnetii (Phase I) by monoclonal antibodies
Authors: Mccaul T. F. , Williams J. C.
Published: June 2020

Coxiella burnetii, the etiological agent of Q fever, is an obligate phagolysosomal bacterium and an unorthodox spore former. Morphologically distinct cell types, produced by a developmental cycle, are defined as large cell (LCV) and small cell variants (SCV). Recent study has shown phase I lipopolysaccharide (LPS-I) is differentially expressed among the cell variants. This antigenic variation was investigated further by use of a series of monoclonal antibodies (MAbs), directed against LPS-I, and post-embedding immunolabelling techniques. Since these MAbs recognize carbohydrate determinants of LPS-I, the specificity of the labelling was tested by carbohydrate reducing and oxidizing reagents prior to labelling.

C. burnetii (9MIC7 strain), which was purified from infected yolk sac material of hen eggs by Renografin gradient centrifugation, was fixed for 3 h in 1.5% glutaraldehyde and 0.2% picric acid in 66mM Na-cacodylate buffer, pH = 6.8; pre-embedded in 2% Difco Nobel agar; and then rinsed once (15 min) in the same buffer.
Scanning electron microscopy of pneumocoptes penrosei (Weidman) from the black-tailed prairie dog, Cynomys ludovicianus
Authors: Nunamaker C.E. , Williams E.S. , Sherman S.L.
Published: June 2020

Pneumocoptes penrosei (Weidman 1917) is a parasitic mite that infests the lungs of the prairie dog, Cynomys ludovicianus. Taxonomic characterization of these mites has been previously described using light microscopy, however, scanning electron microscopy (SEM) provides a more detailed view of these arthropods.

In December, 1987, a black-tailed prairie dog was submitted to the Wyoming State Veterinary Laboratory, Laramie, WY. The prairie dog had been in captivity for several years and had recently lost weight. No lesions were observed on gross examination. The lung was normal on light microscopic examination, however, numerous cross sections of mites were observed within the alveoli. Samples of the mite infested tissue were prepared for scanning electron microscopy. One group of formalin-fixed lung tissue was digested in acid pepsin at 37°C in a shaker waterbath for 12 hours. The mites were removed from the digested tissue, transferred into phosphate buffer, and centrifuged at 1500 rpm for two minutes prior to post-fixation in 1% OSO4 on ice for 30 minutes.
The homogeneity and radiation sensitivity of a calcium-containing low-viscosity resin for use as a standard in analytical electron microscopy
Authors: Armstrong David A.
Published: June 2020

The availability of good elemental standards is essential for the quantitative analysis of soft biological tissues. A standard that contains a homogeneous distribution of the elements of interest, has a high level of stability in the electron beam, and models the specimen in chemical composition would be an ideal case. We are involved in a continuing investigation examining both the homogeneity and the radiation sensitivity of a set of prepared standards. Here we report the initial results, with regard to calcium distribution within, and radiation sensitivity of, a calcium containing low viscosity epoxy resin.

Calcium Naphthenate was incorporated into Spurr's resin using a protocol given by Simon (personal communication), from concentrations of 30 millimoles of calcium per kilogram of resin to l00mm/kg of resin.
The maximum-likelihood method for em autoradiography: Small-system implementation technique
Authors: Roysam Badrinath
Published: June 2020

Electron Microscopic Autoradiography (EMA) is of growing importance as a technique for the quantification of radiolabelled biochemicals in subcellular structures. The Maximum-Likelihood (ML) method of Miller et al. has been shown to be substantially superior to the conventional crossfire (OF) method. In this paper, we present a method for reducing the computational requirements of the ML method to a point where it becomes feasible to implement it on a small computer. We then describe EMA/PC, which is a device-independent computer program that implements the complete ML method on the IBM-PC class of machines.

We have shown that the iterative Expectation-Maximization (EM) algorithm has a high computational complexity which can be reduced dramatically via a problem reformulation which involves the computation and use of sufficient statistics, which we call Grain-Organelle Probabilities (GOPs). The computation of GOPs requires the integration of a two-dimensional point-spread function over regions defining subcellular structures in the given set of electron micrographs.
Atom-probe microscopy
Authors: Kellogg G. L.
Published: June 2020

The atom-probe field ion microscope is a highly-sensitive, time-of-flight mass spectrometer which is used to identify individual atoms or groups of atoms that appear in a field ion microscope image. Under ideal conditions the atom-probe can yield the surface and bulk composition of a solid sample with true atomic spatial and depth resolution. Since its development in the late 1960's, the atom-probe has been used to study a variety of problems in the areas of metallurgy, surface science, and materials science. This review focuses on operational principles of the atom-probe and selected applications carried out in the author's laboratory.

The most widely-used atom-probe follows the original design developed by Müller, Panitz and McLane. In this instrument a small probe-hole is placed in the viewing screen of a field ion microscope. The image is adjusted such that the atom or atoms of interest are in alignment with the probe hole.
A study of small probe formation in a field emission gun TEM/STEM
Authors: Veiss J. K. , Carpenter R. W.
Published: June 2020

A Philips EM 400T equipped with a field emission gun (FEG) has been studied to determine the spatial and angular current distribution in the electron microprobe at the specimen level. The field emission gun provides a high brightness source capable of producing electron probes with diameters of several nanometers and total currents of 0.05 - 50 nA. The advantage of the TEM/STEM over the dedicated STEM in this study is its ability to produce real-space images of the probe at the specimen plane. Detailed information about the probe current distribution can be experimentally obtained and applied to various small-probe techniques (i.e. HRAEM, STEM, microdiffraction) in order to determine their spatial resolution.

The probe diameters listed in Table 1 were measured from high magnification images of the focussed probes which showed sharply defined outlines of the aberration figures. Additional measurements were obtained by scanning the probe across a small fixed entrance aperture to an EELS spectrometer, and also by an edge resolution method similar to that used by Venables and Janssen.