bluuebunny/crossref_metadata_2025 huggingface dataset:
Relative translations of adjacent crystals in twin boundaries
Authors: Pérez R.
Published: June 2020

Theoretical simulations of twin boundary contrast carried out in the past have shown that a relative translation of one crystal with respect to the other may exist. The first method proposed in the literature to determine this translation was given by Pond et. al and Pond This technique has been independently developed by Marukawa, who gave experimental evidence supporting an atomic model of twin boundary on [211] in which the adjacent crystals have mirror symmetry across the twin boundary as opposed to a structure where the two crystals are relatively translated parallel. However, this conclusion has been criticized in the literature. In this communication some recent results obtained in Cu are discussed. These experimental results suggest in one case that the adjacent crystals in a twin boundary have mirror symmetry across the boundary. However, in other cases, the presence of a body translation vector is clearly indicated. Experimental images of twin boundaries have been obtained from wedge shaped specimens of Cu.
Electron microscopy of oxide and sulfide scales on iron and nickel
Authors: Hobbs Linn W.
Published: June 2020

Corrosion scales formed by oxidation and sulfidation of metals at high temperature have long been the traditional preserve of metallurgists and electrochemists armed with light-optical metallography and gravimetry. It has been only recently that electron microscopical techniques have made a substantial impact on the understanding of scale microstructure and morphological development and on knowledge of extended defect structure accommodating the nonstoichiometry imposed by activity gradients sustained across scales. An important advance was the perfection of techniques for consistently producing transverse sections across scale and substrate (Fig. 1) which reliably preserve both scale/substrate and substrate/gas interfaces.

This contribution focuses on several intriguing microstructural features of the ‘simple’ scales NiO, FeO and FeS formed on pure metal substrates, in which the predominant form of mass transport is outward diffusion of metal via inward diffusion of cation vacancies, so that new scale is formed at the scale/gas interface.
A newly developed 200-kV analytical electron microscope
Authors: Tomita T. , Iwatsuki M. , Arai Y. , Ishida Y. , Ibe K. , Kersker M.
Published: June 2020

In the fields of material science, analysis of ultramicroareas has recently become important to develop new functional materials such as semiconducting compounds and ceramics. A 200 kV electron microscope has been developed for ultramicroarea structural and chemical analysis with a fine electron probe a few nm in diameter in the TEM and STEM modes. The present paper reports some features of the electron microscope.

The illumination lens system consists of a four condenser lenses (1st condenser; CL1, 2nd condenser; CL2, condenser mini; CM, and upper objective lens) to change the probe size over a wide range in the TEM mode. Two combination of excitation conditions for pre-aligned illumination lenses controlled by micro-processor is used to get a exact correspondence between the fine structure under high resolution image observation and the area a few nm in diameter under analysis.
Inexact reconstruction: B. Application to a biological object
Authors: Kapp O.H. , Crewe D.A. , Crewe A.V.
Published: June 2020

A serious limitation in the 3D reconstruction of aperiodic objects in the electron microscope is imposed by the difficulty in assigning the correct relative orientation to a population of molecules which may present themselves in any number of positions on the substrate. Additionally, some orientations may be found far more frequently than others. The hemoglobin of Lumbricus terrestris presents itself in only three or four easily recognizable positions in the EM. We have recently examined the possibility of inexact 3D reconstruction from a limited number of 2D projections and would like to apply this technique to this molecule using only the three most frequently found orientations (a ‘top’, ‘side’, and 45° diagonal) whose positions relative to one another can be interpreted with reasonable confidence.
Three-dimensional structure of mitochondrial outer-membrane channels from fungus and liver
Authors: Mannella C. A. , Radermacher M. , Frank J.
Published: June 2020

The mitochondrial outer membrane (OM) contains a class of 30-kD polypeptides called VDAC, for the voltage-dependent, anion-selective channel activity which they induce in phospholipid membranes. VDAC occurs in extended periodic arrays on the outer membranes of mitochondria of the fungus Neurospora crassa. The arrays are polymorphic, varying from a parallelogram lattice (Fig. 1a) with six negative-stain-accumulating sites per unit cell (a=12.6 nm, b=11.1 nm, θ=109°) to a rectangular lattice (Fig. 1b) with two densely staining loci per unit cell (a=8.5 nm, b=5.0 nm). We have calculated the three-dimensional structure of the oblique OM array embedded in uranyl acetate. Images were recorded from a crystalline membrane which was tilted relative to the 100keV electron beam from +40° to -40° in 10° intervals. A common crystalline area in each image was Fourier-filtered by a quasi-optical procedure using reflections out to 1/(3.0 nm). Following rotational and translational alignment, the images were used to reconstruct the OM array in three dimensions by a weighted back-projection procedure.
Pierce's disease bacterium in petiolar xylem of grape leaves
Authors: Tyson G. E. , Stojanovic B. J. , Kuklinski R. , DiVittorio T. , Sullivan M.
Published: June 2020

Pierce's disease (PD) of grapevines is caused by a rod-shaped, gram-negative bacterium that is transmitted by xylem-feeding suctorial insects. Petioles from a grapevine (four-year old French-American hybrid, cultivar DeChaunac) with overt symptoms typical of PD were examined by conventional scanning and transmission electron microscopy in order to describe the external morphology of intraxylar bacterial aggregates and to verify the presence of features known from previous studies to be characteristic of PD bacteria. These features included the size and rod-shape of the bacterium (1.0-2.2 μm long, 0.39-0.53 μm wide), the ridged nature of the bacterial surface (Fig. 1), the membrane-like ultrastructure of the cell wall typical of gram-negative cells, and the xylem-limited occurrence within the host plant.
Electron microscopic assays of restriction endonuclease cutting, exonuclease digestion, and hybridization
Authors: Hannibal Mark , Varkey Jacob , Beer Michael
Published: June 2020

Workman and Langmore have recently proposed a procedure for isolating particular chromatin fragments. The method requires restriction endonuclease cutting of the chromatin and a probe, their digestion with two exonucleases which leave complimentary single strand termini and low temperature hybridization of these. We here report simple electron microscopic monitoring of the four reactions involved.

Our test material was ϕX-174 RF DNA which is cut once by restriction endonuclease Xho I. The conversion of circles to linear molecules was followed in Kleinschmidt spreads. Plate I shows a circular and a linear DNA molecule. The rate of cutting is shown in Figure 1.

After completion of the endonuclease cutting, one portion of the DNA was treated with exonuclease III, an enzyme known to digest the 3' terminals of double helical DNA. Aliquots when examined in the electron microscope reveal a decreasing length of double helix and increasing bushes at the ends.
Lymphoproliferative disorders (LPD) involving lungs: T and B cell subsets within pulmonary infiltrates and in peripheral blood
Authors: Stachura Irene , Dalbow Milton H. , Niemiec Michael J. , Pardo Matias , Singh Gurmukh , Hartsock Robert J.
Published: June 2020

Lymphoid cells were analyzed within pulmonary infiltrates of six patients with lymphoproliferative disorders involving lungs by immunofluorescence and immunoperoxidase techniques utilizing monoclonal antibodies to cell surface antigens T11 (total T), T4 (inducer/helper T), T8 (cytotoxic/suppressor T) and B1 (B cells) and the antisera against heavy (G,A,M) and light (kappa, lambda) immunoglobulin chains. Three patients had pseudolymphoma, two patients had lymphoma and one patient had lymphomatoid granulomatosis.

A mixed population of cells was present in tissue infiltrates from the three patients with pseudolymphoma, IgM-kappa producing cells constituted the main B cell type in one patient. In two patients with lymphoma pattern the infiltrates were composed exclusively of T4+ cells and IgG-lambda B cells predominated slightly in the patient with lymphomatoid granulomatosis.
Lattice Image Studies of Ordered Alloys
Authors: Sinclair R. , Dutkiewicz J.
Published: June 2020

Lattice imaging is becoming a viable technique for investigating the structure, defects and early stages of phase transformations in ceramics and metals. Our interest lies in its application to the study of ordering in alloys. Conventional images yield little information on the local degree of order in the specimen, the image width of defects may be as great as 50Å, and the interpretation of diffaction patterns and superlattice dark field micrographs is sometimes ambiguous. The advantage of the lattice image is its ability to provide data about atomic environment (from the nature of the lattice fringe profile) and to reveal atomic arrangements near defects.
Generation of 4H and 6H Structures During the Hexagonal-Rhombohedral Transformation in Dy2Co17
Authors: Allen C. W. , Kuruzar D. L.
Published: June 2020

The rare earth/transition element intermetallics R2T17 are essentially topologically close packed phases for which layer structure models have already been presented. Many of these compounds are known to undergo allotropic transformation of the type at elevated temperatures. It is not unexpected that shear transformation mechanisms are involved in view of the layering character of the structures. The transformations are evidently quite sluggish, illustrated in furnace cooled Dy2Co17 by the fact that only rarely has the low temperature rhombohedral form been seen. The more usual structures observed so far in furnace cooled alloys include 4H and 6H in Dy2Co17 (Figs. 1 and 2) . In any event it is quite clear that the general microstructure is very complicated as a consequence of the allotropy, illustrated in Fig. 3. Numerous planar defects in the layer plane orientation are evident as are non-layer plane defects inherited from a high temperature structure.
Transmission Electron Microscopy of the Deformation Structures in Silicon Carbide
Authors: Clarke D.R.
Published: June 2020

Silicon carbide is, like many other candidate ceramics for high temperature applications, brittle when tested macroscopically. However, little is known about its deformation at a microscopic scale. This contribution reports the observation of limited plasticity and microscopic cracking produced during fracture of silicon carbide.

The material used in this work was a dense sub-micron grain size silicon carbide produced by hot pressing with the addition of a small quantity of boron. Disc specimens suitable for examination in a Philips EM 301 microscope were prepared by mechanical grinding and subsequent ion thinning. Deformation was then introduced by the simple expedient of breaking the specimen after mounting it on an electron microscope grid. The material has the cubic structure (β).
Fine Structure in the Selected Area Electron Diffraction Patterns of Beidellite
Authors: Güven N. , Pease R.W.
Published: June 2020

Selected area electron diffraction (SAD) patterns of beidellite exhibit fine structure in the form of nonradial streaks and extra spots between the normal Laue spots. The streaks form a regular network as shown in Figure 1A andvery clearly after a long exposure, in Fig. IB. These streaks do not pass through the origin and they are not symmetrical with respect to the reciprocal lattice points. Therefore they cannot be caused by finite crystallite size. The distribution of the streaks suggests a strong anisotropy in the beidellite structure as they are restricted to the directions parallel to [11], [11], and [02]. However, there are no streaks along the actual [11], [11] and [02] directions. In general terms, these linear streaks are explained by the presence of ‘continuous sheets’ or ‘walls’ of intensity in reciprocal space. These intensity 'walls' are associated with a linear chain of scatterers in the crystal in the direction perpendicular to the intensity sheets. Such linear scatterers may be produced by small shifts of certain atoms due to thermal motion, isomorphic substitutions, distortions, or other lattice imperfections.
Observations on the Fine Structure of Siliceous Microfossils from the Oamaru Diatomite (Upper Eocene, New Zealand). I. Silicoflagellates
Authors: Jendrzejewski John P.
Published: June 2020

Silicoflagellates are single-celled flagellated protists that secrete a relatively simple siliceous skeleton generally less than 100 microns in length. Silicoflagellate skeletons have been recovered from many types of marine deposits and have been utilized by geologists in biostratigraphic and paleoecologic analysis. The systematics of this group is established upon overall skeletal morphology. Recently, the importance of ornamentation found on the surface of these skeletons has been emphasized The surface of the silicoflagellate skeletons may be smooth, or ornamented with spines, warts, linear striations, ridges and complex reticulations (i.e. ridges of silica in which at least three converge to a point on the skeleton).
Performance and Applications of a High Resolution Field Emission STEM
Authors: Banbury J.R. , Drummond I.W. , Ray I.L.F.
Published: June 2020

This paper discusses the latest developments and results obtained from a field emission scanning transmission microscope. Some features of the instrument have already been described. The microscope has been in routine operation for more than two years at accelerating voltages of 80 and 100kV. Over this period a number of (111) and (310) oriented tungsten tips have been fitted and operated for varying periods in order to access the minimum lifetime to be expected. No tip has yet failed in service, and the (111) tip in current use has given more than 500 hours of stable and trouble free operation, in a vacuum of 3 to 5 x 10-11 torr.
Design of Sensitive Photographic Materials for the High-Voltage Electron Microscope
Authors: Vernon King Murray , Parsons Donald F.
Published: June 2020

Effective application of the high-voltage electron microscope to a wide variety of biological studies has been restricted by the radiation sensitivity of biological systems. The problem of radiation damage has been recognized as a serious factor influencing the amount of information attainable from biological specimens in electron microscopy at conventional voltages around 100 kV. The problem proves to be even more severe at higher voltages around 1 MV. In this range, the problem is the relatively low sensitivity of the existing recording media, which entails inordinately long exposures that give rise to severe radiation damage. This low sensitivity arises from the small linear energy transfer for fast electrons. Few developable grains are created in the emulsion per electron, while most of the energy of the electrons is wasted in the film base.
The Formation and Growth of Crystal Defects in Nickel-Base Alloys Under Proton Irradiation
Authors: Chen L.J. , Ardell A.J.
Published: June 2020

The investigation of radiation effects in Ni-base alloys has continued to be of interest to the long range LMFBR program. Several Ni-base alloys (Ni-Al, Ni-Cr, Ni-Ti) have been chosen to investigate the fluence dependence of damage, the influence of structural variables and the effect of temperature under proton irradiation.

For this transmission electron microscopy (TEM) study, both samples of about 5 mil. thickness and thin perforated samples have been irradiated with fluences up to 3.6 x 1019/cm2 and beam intensity about 100μA/cm2. The irradiation of thin perforated samples enormously simplifies the specimen preparation routine and augments the quantity of observations while giving useful and semi-quantitative data.
High Temperature Strength and Stability of Oxide Dispersion Hardened Alloys
Authors: Grewal M.S. , Sastri S.A. , Grant N.J.
Published: June 2020

The creep behavior of oxide dispersed alloys can be described by the following equation:

where ε is steady state creep rate, σ applied stress, R gas constant, T temperature in °K, Qc activation energy for creep, n stress exponent, A and n are constants.

Two unusual observations in the case of O.D. alloys are that Qc and n take on values that have not been explained satisfactorily. This investigation was undertaken to explain the unusually high strength, high Qc and high stability (high value of n) in the oxide dispersed alloys.
Crystal Support Contrast
Authors: Hines R. L.
Published: June 2020

Single crystal support films can be used to enhance the electron microscope image contrast of amorphous phase objects if the objects are viewed in the vicinity of strong bend contours. When the objects are supported on top of the crystal film, the incident electron wave will be scattered by the specimen before it goes through the crystal. For a thin object the wave scattered to an angle θ with respect to the incident wave will be small in amplitude and the incident wave will not be appreciably changed. The incident wave will be strongly diffracted when it strikes the crystal support and the diffracted portion can be easily removed with an objective aperture. The remaining portion of the incident wave will in general be shifted in phase.
Simulated Dark-Field Electron Micrographs of Point Defects and Organometallics
Authors: Krakow William
Published: June 2020

Tilted beam dark-field microscopy has been applied to atomic structure determination in perfect crystals, several synthesized molecules with heavy atcm markers and in the study of displaced atoms in crystals. Interpretation of this information in terms of atom positions and atom correlations is not straightforward. Therefore, calculated dark-field images can be an invaluable aid in image interpretation.
Electron Diffraction of Wet, Unstained, Unfixed Rat Hemoglobin
Authors: Dobbs B. C. , Pangbom W. A. , Parsons D. F.
Published: June 2020

Electron diffraction provides a method for studying the structure of molecules which are obtainable only as microcrystals, since the scattering amplitudes for electrons are at least 103 greater than for X-rays. Included in this class of molecules are many of biological interest. However, most compounds of biological interest require a hydrated environment to maintain their crystal integrity, and have therefore, not been suitable for high resolution electron diffraction. The development of the hydration stage has given new impetus to the electron diffraction of hydrated crystals as demonstrated with catalase.

Sickle cell anemia, a disease which is associated with a hemoglobin that is insoluble in physiological media, provides semi-ordered hemoglobin filaments which may be investigated by electron diffraction. As a first model in investigating such a system, rat hemoglobin, which crystallizes in physioligicaL media (3), has been chosen.
Etching Techniques and the Surface Morphology of the Gunflint Chert
Authors: Johnson A. H.
Published: June 2020

Samples of the Gunflint Chert (2.0 billion years old), collected near Kakabeca Falls, Ontario by Dr. L. P. Knauth, have yielded several distinct and recurring morphologies when in hydrofluoric acid of varying concentrations for varying lengths of time, and viewed with a scanning electron microscope.

The chert is entirely siliceous, with the exception of minor calcareous lenses identified by energy dispersive analysis. Previous studies of the Gunflint Chert have been made using TEM however SEM offers a three dimensional view which greatly aids interpretation.

The samples were prepared by fracturing followed by etching in HF for 30 seconds to 48 hours with concentrations varying from .5% to 30%. It appears that the optimum concentration and etch time varies according to the particular morphology one wishes to develop. This is due to the difference in response to HF by the different textures in the rocks.
Jet-Polishing Iridium for TEM
Authors: Braski D. N. , Potter G. A.
Published: June 2020

Iridium is an extremely dense and chemically resistant element. These properties make it one of the most difficult metals to examine by TEM. Various electrochemical techniques for preparing Ir TEM samples which use the "window" method have been reported. Iridium has also been thinned by ion milling. However, the "window" method requires relatively large foil samples and the technique is likely to introduce dislocations into the microstructure. We also verified that techniques using KCN resulted in severe grain boundary attack. Ion milling is very slow and creates "black spot" ion damage which can mask small microstructural features such as precipitates or small dislocation loops. A relatively rapid jet-polishing technique which alleviates these problems is described below.
Determination of Crystal Thickness from Relative Transmission Measurements
Authors: Joy D. C. , Maher D. M.
Published: June 2020

An accurate knowledge of the specimen foil thickness often is required in quantitative transmission electron microscopy. The methods used for thickness determinations of thin crystalline materials (e.g. the trace method, thickness fringe counts and stereoscopic measurements) generally are selected according to the history of the specimen and nature of the microstructure. For amorphous materials a measurement of the relative transmission of electrons I/I0, where I is the transmitted and I0 the incident electron intensity, affords an accurate estimate of the specimen thickness. In this case, for a sufficiently large specimen thickness, I/I0 varies exponentially according to the mass thickness relationship e-μt, where μ is the mass absorption coefficient and t is the specimen thickness. The purpose of this paper is to demonstrate that the thickness of a crystalline specimen also may be determined accurately from a measurement of I/I0, provided that well defined diffracting conditions are used. The results presented here are for silicon.
The Platinum-Carbon Shadow Width Increase as a Function of Rnown Particle Size on Non-Planar Surfaces
Authors: Ruben G. C. , Telford J. N.
Published: June 2020

Internal fracture faces of membranes show platinum/carbon (pt/c) shadowed particles averaging in size from 80 to 200 Å. Only two of these internal membrane particles have been identified. Since the shadowed particles often reside on non-planar surfaces of the membrane fracture face, it would be very useful if the increased particle width due to shadowing could be calibrated as a function of real particle width.

A test specimen was made in the following manner. Indirectly evaporated carbon films of 40 Å thickness were produced on freshly cleaved mica. The indirectly evaporated carbon film was then mounted on 300 mesh grids. Following this procedure, a heterogeneous sized population of gold particles was deposited on the film surface by evaporating gold very slowly in 900 mm of Helium. The 300 size mesh grids were selected in order that the carbon film would sag in the middle thereby providing a variety of angles relative to the source of shadowing.
Improved Resolution in Three-Dimensional Image Reconstruction of Helical Structures
Authors: Amos L. A.
Published: June 2020

There are two main approaches to the problem of improving the resolution attainable by three-dimensional image reconstruction from electron micrographs. One is to find improvements in specimen preparation and microscopy, the other is to reduce the background error in the images by averaging data from a number of carefully selected images. This paper is concerned with applying the latter approach to helical structures, whose individual images include many different views of identical subunits. The example chosen is the contractile tail of T4 bacteriophage (Fig. 1), the structure to which DeRosier and Klug first applied 3-D reconstruction techniques, and which they solvedto about 38Å resolution from single images. Our new map of the extended tail, calculated by combining data from images of several different specimens, is at a resolution of about 20Å and shows the substructure in more detail. We have also calculated a 3-D map of the contracted structure, although in this case the poorer quality of the data has limited the resolution to 32Å.
Enucleation of Colchicine Treated Mammalian Cells
Authors: Shay Jerry W. , Clark Mike A.
Published: June 2020

In 1967 Carter reported that the drug cytochalasin B (CB) causes the nucleus of most mammalian cells growing in monolayer culture to protrude from the cell surface and that a small percentage of these cells spontaneously enucleate. Prescott et al. discovered that by using centrifugation in the presence of CB up to 98% of the cells remaining attached to the substrate can be enucleated. One could thus separate cells into nuclear (karyoplast) and cytoplasmic portions. The surface morphology and fine structure of these components have been described. In another area of research Phillips and Phillips earlier reported that when logarithmically growing mammalian cells were treated with 5.0 x 10-5 M colchicine for 16-36 hours a majority of the cells become micronucleated. Recently Ege and Ringertz reported that colchicine induced micronucleated cells can also be enucleated by combining centrifugation with CB treatment [5].
Giant Mitochondria in Hepatocytes Following Concanavalin A Administration
Authors: Nopanitaya Waykin , Tyan Marvin L.
Published: June 2020

Concanavalin A (Con A), a protein obtained from the jack bean, has been used intensively in vitro in a topographical study of the structure of cell plasma membrane. In vivo toxicity following a single dose of intravenous injection of Con A has been recently noted in the mouse during an investigation of the immunosuppressive properties of this known phytohaemagglutinin. In that preliminary report, histopathological changes in various organs including the liver were described by light microscopy. Ultrastructural changes in hepatocytes caused by Con A have not been described. Presented here are observations on the ultrastructural alterations in hepatocytes and their mitochondria following a single dose of intravenous injection of this toxic lectin.

Concanavalin A in a balanced salt solution (800 μg Con A in 0.2 ml) was individually given intravenously to adult male B6D2F1 mice. Groups of mice were sacrificed by cervical dislocation 1, 2, 7, 14, and 28 days after the injection of Con A.
Quantitative Electron Microprobe Studies of Human-Platelet Dense Bodies
Authors: Tanaka Y. , Costa J.L. , Pettigrew K.D. , Yoda Y. , Cushing R.J.
Published: June 2020

As seen in air-dried whole mounts, human-platelet dense bodies (DB) are discrete, electron-opaque structures ranging in size from approximately 50 nm to 1000 nm in diameter (Fig. 1). We have examined DB elemental composition and peak-to-background (p/bg) ratios using a Hitachi HU-12A microscope in the transmission-scanning mode and a Kevex energy-dispersive X-ray detector and analysis system. Qualitatively, spectra from probed DB showed strong signals for calcium and phosphorous, and a less prominent peak for potassium. No magnesium peak was detected (Fig. 2).

Quantitatively, probing 11 randomly-selected DB with a beam spot approximately 10 nm in diameter (75 kv accelerating voltage) gave phosphorous p/bg ratios with a coefficient of variation (CV) of 71.32, calcium p/bg ratios with a CV of 75.34, and elemental phosphorous/calcium (P/Ca) ratios with a CV of 18.10 (Fig. 3). Peak-to-background ratios for both elements demonstrated low correlations with the area of the DB probed (r = 0.12 and 0. 39 for phosphorous and calcium, respectively, based on a sample size of 67 DB's), suggesting that only a small fraction of the total DB area was being sampled.
Lectin Binding Studies on RNA Tumor Virus-Infected Cells
Authors: Hixson D. C.
Published: June 2020

The abilities of plant lectins to preferentially agglutinate malignant cells and to bind to specific monosaccharide or oligosaccharide sequences of glycoproteins and glycolipids make them a new and important biochemical probe for investigating alterations in plasma membrane structure which may result from malignant transformation. Electron and light microscopic studies have demonstrated clustered binding sites on surfaces of SV40-infected or tryp- sinized 3T3 cells when labeled with concanavalin A (con A). No clustering of con A binding sites was observed in normal 3T3 cells. It has been proposed that topological rearrangement of lectin binding sites into clusters enables con A to agglutinate SV40-infected or trypsinized 3T3 cells (1). However, observations by other investigators have not been consistent with this proposal (2) perhaps due to differences in reagents used, cell culture conditions, or labeling techniques. The present work was undertaken to study the lectin binding properties of normal and RNA tumor virus-infected cells and their associated viruses using lectins and ferritin-conjugated lectins of five different specificities.
Propagation of JC Virus in Glia Cells in PML (Progressive Multifocal Leukoencephalopathy
Authors: Preskorn S. , Kepes J. , Bopp W.J. , Watanabe I.
Published: June 2020

PML, a rare form of subacute demyelinating disease of the human brain, is caused, in most instances, by JC virus, a new type of papova virus. Light microscopically, the lesions are characterized by hypertrophy of oligodendroglia with intranuclear inclusion and gigantic astroglia with bizarreshaped nuclei. Although viral particles have been found by many investigators, the use of autopsy material has limited the ultrastructural study of changes in the patient.

This report concerns some new cytopathological changes based on an electron microscopic study of well fixed biopsy material. Oligodendroglia and astroglia were markedly hypertrophic, but were identified by the presence of abundant cytoplasmic microtubules and filaments, respectively. Intranuclear and intracytoplasmic virions were found in both cell types. The intranuclear virions were the typical round and filamentous forms, with diameters of 40 and 30 mμ, respectively. They were scattered randomly throughout the enlarged nuclei.
Fine Structural and Pathologic Evaluation of Moloney Sarcoma Virus (MSV) -Induced Osteosarcoma in the Rat
Authors: Olson H. M. , Capen C. C.
Published: June 2020

Osteosarcoma, an important neoplastic disease particularly in young male adults, has been produced experimentally in the rat or hamster by bone-seeking radionuclides (90Sr, 45Ca.), extracts of human osteosarcoma, and viruses (MSV) (Ikemoto and Yamamoto, Gann 63:141, 1972 and Soehner and Dmochowski, Nature 244:191, 1969). In our investigations experimental osteosarcomas were produced in neonatal (less than 24 hours old) New Zealand black rats by direct intratibial inoculation of a MSV preparation in citrate buffer and equine serum. The objective of this investigation was to characterize a MSV-induced osteosarcoma model in the neonatal rat by radiographic, light and electron microscopic evaluation.

Bone tumors could be detected by palpation as soon as 20 days after virus inoculation. The tumor incidence achieved in inoculated litters has reached 55% (5/9 rats) in our laboratory. Sequential radiographs in rats demonstrated evidence of both osteolytic and osteoproliferative activity in the tumor, with progressive dissolution of tibial cortical bone (Fig. 1).
Electron Microscopy of Wound Healing in Patients with Hernia
Authors: Sun C.N. , White H.J. , Read R.C.
Published: June 2020

Previously we have reported the defect of collagen fibrils from herniated rectus sheath. This presentation includes additional sections from postsurgical incisions (10 days) from both control and hernia patients. Small pieces of rectus sheath were fixed in 3% glutaraldehyde in phosphate buffer (pH 7.2) and post fixed with buffered 2% osmium tetroxide. The tissues were then dehydrated in serially increasing concentrations of alcohol and embedded in Epon 812. Sections were stained with 2.5% phosphotungstic acid or uranyl acetate and lead citrate.

Previously we found that collagen fibrils from "non-herniated" rectus sheath have uniform diameters and 640 Å periodicity with seven or more intraperiodic bands resembling typical native collagen fibrils, while the fibrils from fascia obtained from patients with direct herniation show considerable variation in diameter. These variations are often found in the same individual fibers with a range from 300 Å to 3000 Å.
Fine Structural Features of Neurosarcomas
Authors: Mackay Bruce , Valenzuela Jorge , Butler James J.
Published: June 2020

In an electron microscopic study of an extensive series of malignant tumors of the soft tissues, sarcomas derived from elements of the peripheral nervous system were observed to possess unique morphologic features. Since these features were not seen in any of the other types of soft tissue sarcoma, they are useful as diagnostic criteria. They also provide insight into the histogenesis of neurosarcomas.

By light microscopy, some neurosarcomas are seen to be composed of compactly grouped, spindle-shaped cells, and intercellular connective tissue is scanty. In other neurosarcomas, dendritic or stellate cells are loosely arranged in a relatively clear, occasionally myxoid-like stroma. The two types of tissue frequently coexist in the same neoplasm, and both are common in benign tumors of the peripheral nerves.

Figure 1 shows part of a tumor cell from a neurosarcoma of the loosely-textured variety. The cytoplasm extends into a slender branching process containing longitudinally-oriented microtubules and fine filaments.
Tissue Response to Vascular Prosthetic Materials
Authors: Narconis R.J. , Spindler J.W. , Billy L.J. , S. Rana
Published: June 2020

Tissue response to three types of vascular prosthetic materials was evaluated by correlation of scanning electron microscopy and light microscopy. Two clinically established materials, woven dacron and woven teflon, and an experimental material, expanded polytetrafluoroethylene (Goretex) were employed. They were implanted in the subcutaneous tissue of rats and removed at time intervals ranging from 48 hours to 30 days. Half of the retrieved material was fixed in 10% formalin and examined by routine light microscopy. The other half was glutaraldehyde fixed and acetone/CO2 critical point dried, then examined by scanning electron microscopy.

Prior to this study, the three materials were evaluated by scanning electron microscopy to establish topographic landmarks. The woven dacron had bundles of relatively large, rough fibers; the woven teflon had fibers of similar size but with a smooth surface; the PTFE, however, had a surface composed of fibers and pores only a few micra in diameter.
Scanning Electron Microscopy of Carcinoma and Precancerous Lesions of the Colon
Authors: Siew S.
Published: June 2020

In this investigation, fresh operative resected specimens showing carcinoma of the colon and presumed precancerous lesions, such as, adenomatous polypi, were examined by means of scanning electron microscopy. In addition, a study was made of small (2-3 mm) discrete nodules which were observed in apparently unaffected mucosa in such cases.

Scanning electron microscopy of normal colonic mucosa shows an even, undulating pattern, punctuated at regular intervals by the invaginations of the crypts. The crypt openings are surrounded by slightly raised clusters of cells. The cellular configuration is fairly uniform with regard to the size, shape and polarity of the cells. The luminal surface is serrated owing to the presence of microvilli which form fine regular projections over the whole border of the intact cell. (Fig. 1)

The small discrete nodules show an uneven mammilated surface which is divided by deep clefts into unequal lobules.
Ultrastructural Changes in Dog Thyroid Follicular Cells Induced by Chronic Thyrotropin Administration
Authors: Fernandez-Pol J. A. , Hays M. T.
Published: June 2020

The acute ultrastructural effects of Thyroid Stimulating Hormone (TSH) in vivo or in vitro are well documented. However, little is known about chronic effects of TSH administration. The purpose of the present study was to define the ultrastructural changes induced by chronic TSH administration.

Ten Mongrel dogs weighing between 18-20 kg were used in these studies. They were divided in two groups:

Control group: (4 dogs) These dogs were administered saline solution, (0.09% NaCl) intramuscular for 10 days.

TSH treated group: (6 dogs) These dogs received a daily intramuscular
injection of TSH, 15 IU for 10 days.

All dogs received 300 mg of Thyroid extract per day for 3 days prior to the operation. Then, they were thyroidectomized on the 11th day. Immediately after removal of the thyroid gland, tissues were fixed in glutaraldehyde 37, in phosphate buffer at pH 7.4 for 2 hrs.
Cytochemical Localization of Acid Phosphatase in WI-38 Cells Observed by HighVoltage Electron Microscopy
Authors: Wolosewick John J. , Porter Keith R.
Published: June 2020

One of the major problems in the interpretation of high voltage electron micrographs of whole cultured cells results from the superimposition of membranes, filaments, ribosomes, etc., in the final 2-dimensional image. The gains provided by the greater penetrability and resolution of the higher energy beam are to some extent lost in the confusion introduced by the overlap of structures. The problem is overcome in part by stereomicroscopy and this becomes the routine procedure for thick specimens. The effectiveness of this is greatly improved, however, if the object or organelle of special interest can be selectively stained. Toward this end we have explored the use of cytochemical techniques which identify the distribution of certain intracellular enzymes. The results will be illustrated with procedures for acid phosphatase.

The “aging” human diploid cell line WI-38 (passages 25-30) was cultured on sterilized, formvar-coated gold grids lightly shadowed with carbon. The cells were fixed for 1 hr. at 0-4°C in 2% glutaraldehyde in 0.1M sodium cacodylate (pH 7.2) plus 0.1M sucrose.
Na+K+ Dependent Atpase as a Specific Marker for Myoepithelial Cells: An Ultrastructural Study.
Authors: Russo J. , Wells P.
Published: June 2020

One of the problems in the study of mammary carcinomas is the cellular heterogeneity which they present. The use of a specific histochemical marker can help to distinguish the two principal cellular types found in the mammary gland; the epithelial and myoepithelial cells.

Mammary glands of female Balb/C mice of different ages were removed and fixed in 1.5% glutaraldehyde in 0.1M cacodylate buffer pH 7.2 with 1% sucrose. After two hours of fixation at 4°C, the material was washed in 0.1M cacodylate buffer, sectioned with a Smith-Farquar microtome set at 70-100u, and incubated for the histochemical detection of ATPases. The tissue was then washed again with 0.1M cacodylate buffer, postfixed in 1% osmium tetroxide, dehydrated, and embedded in an Epon-Araldite mixture.

For the Mg++ dependent ATPase the conventional method of Wachstein and Meisel was followed. The Mg++ dependent ATPase is localized in the plasma membranes of the epithelial and myoepithelial cells (Fig. 1).
Reversible Opening of Junctional Complexes in the Kidney Tubule by Action of Small Concentrations of Urea
Authors: González E. , Pérez-González Margarita , Rawlins F. A. , Whittembury G.
Published: June 2020

In the doubly perfused toad kidney, trace amounts of labelled graded size non-electrolytes which are known to stay in the extracellular space (i.e., mannitol, sucrose raffinose, inulin) were added to the peritubular circulation. Their appearance in the luminal fluid was assessed under control conditions (isosmotic experiments) and when a transtubular osmotic gradient was made hyperosmotic by addition of 50 mM urea to the fluid bathing the tubular lumen (anisosmotic experiments). Under isosmotic conditions the molecules sieved through the tubular wall in an amount which was inversely related to their molecular dimensions. Inulin did not cross the tubular wall. Anisosmotic conditions increased the transtubular movement of each molecule proportionately, again in an amount inversely related to their molecular dimensions. Inulin now crossed the tubular wall. Return to isosmotic conditions decreased the magnitude of the previously increased permeability to the different extracellular nonelectrolytes (1).
Scanning Electron Microscopy of the Taste Bud of the Mudpuppy, Necturus Maculosus
Authors: Samanen David W. , Bernard Rudy A.
Published: June 2020

The tongue of the mudpuppy, Necturus maculosus, appears smooth and without any papillae. Farbman and Yonkers (1971) reported that the tongue contains round elevations or eminences, each with a single, large taste bud. Furthermore, their light micrographs, made of sectioned tissue, showed that the tips of the buds are flush to the lingual surface. In contrast, the mammalian taste buds lie below the epithelium of the lingual papillae and contact the surface only by way of a narrow taste pore. We undertook SEM studies to confirm this morphology, one which would be advantageous for later neurophysiological studies involving the stimulation of individual taste buds and microelectrode recording from taste bud cells.

Figure 1 shows two adjacent eminences from the mudpuppy's distal tongue. The taste bud shows as a surface irregularity, centered at the top of each mound. Their dimensions and general distribution correspond to those reported by Farbman and Yonkers.
Optical Diffraction Of The Z Lattice In Striated Muscle
Authors: Goldstein Margaret A. , Schroeter John P. , Sass Ronald L.
Published: June 2020

Each normal striated muscle fiber has a characteristic Z width at rest length. Previous EM studies of thin Z bands in skeletal muscles have led to a variety of three dimensional models. Recent observations based on thicker Z bands have been incorporated into one of these models. As a first step in understanding three dimensional aspects of the Z band we have constructed a model lattice based on observations of cross sections. We are testing the assumption that regardless of the thickness of the Z band at rest length as observed in longitudinal section, the lattice unit cells as viewed in cross section will be simply related.

Viewing the Z band as a crystalline lattice suitable for analysis by optical diffraction techniques, we are studying a variety of striated muscles in different physiological and pathological states. Muscles are fixed in paraformaldehyde glutaraldehyde and postfixed in osmium tetroxide.
Ultrastructural Changes in the Root Meristem Cells of Rubus Chamaemorus L. (Cloudberry)
Authors: Bal Arya K.
Published: June 2020

In the course of studies in the root meristem tissue of Rubus chamaemorus L. some important changes in the ultrastructural morphology were observed during the initiation of senescence at the end of the growing season.

Root meristems were collected from naturally growing healthy populations of Cloudberry plants, and fixed in Karnovsky's mixture or in 2.5% glutaraldehyde in phosphate buffer. The samples were osmicated, dehydrated following usual methods and embedded in Epon. Ultrathin sections were stained in uranyl acetate and lead citrate.

Figure 1 shows part of a dense cell in the meristem. The electron density of these cells is due to large amounts of a particulate material in the cytoplasmic matrix. The smallest particle seen in electron micrographs is about 40 A, although larger aggregates are also found, which remain randomly distributed in association with various cell organelles. Dense substance has been found associated with golgi membranes, proplastids, vacuoles and microtubules (Fig. 2).
Ultrastructural Localization of Acid Phosphatase in Root Meristem ofAlfalfa Vulgaris
Authors: Mashouf Shaykh M.
Published: June 2020

The present study involves the intracellular distribution of acid phosphatase (AP) in the root meristem ofAlfalfa vulgaris. Root tips, 1-2 mm long, were excised from 24 h old seedlings and fixed in 3% gluteraldehyde in 0.1M PO4buffer at pH 7.2 for 1 h. The fixed roots were washed in the same buffer 3X (15 min each), then incubated for 30 min at 37°C in either Gomori or Barka and Anderson's lead medium with β-glycerophosphate as substrate at pH 5.0. These roots were subsequently washed in the respective buffers of the incubation mixtures and were post-fixed for 30 min in Millonig's OSO4. After brief washing in distilled water the roots were dehydrated in short steps through ethanol, and embedded in Epon for routine Ultramicrotomy. The controls consisted of roots incubated in the incubation mixture lacking substrate and of heat-inactivated (95°C for 15 min) and NaF-treated (0.1M for 2 h) roots incubated in the complete reaction mixture.
Scanning Electron Miscroscopy of Marsilea Sperm
Authors: Shih C. Y.
Published: June 2020

Although spermatogenesis in Marsilea has been studied initially by Sharp with the light microscope (LM), and subsequently by Mizukami and Gall with the transmission electron microscope (TEM), the overall organization of the sperm has not been recorded in detail with photomicrograph. The small size of the sperm (about 16 micrometers in diameter) makes it difficult to resolve the fine detail with the IM and the specimens are too thick to derive useful information by studying whole mount preparations with the TEM. The SEM with a magnification and resolution range which is intermediate between the LM and TEM can be useful to characterize the organization and surface detail of the Marsilea sperm.

Marsilea is a water fern which has the appearance of a four leaf clover. The sporangia are enclosed within a hard, rounded sporocarp which is located at the base of the leaf. Germination of the mature sporocarp can be hastened in the laboratory by excising a small piece of the wall and immersing the sporocarp in water.
An Electron Microscopy Study of the Glycocalyx of Isolated Germinal Cells of the Rat
Authors: Hernández-Jáuregui P. , Trejo-Bayona R. , Delhumeau-Ongay G.
Published: June 2020

The surface coat or glycocalyx of animal and plant cells plays an important role in cell properties such as antigenicity, specific permeability, and ATP ase activity. In the spermatozoa the glycocalyx may be of great importance in capacitation and fertilization phenomena. The glycocalyx is rich in fucose, mannose, galactose and sialic acid. These components are diminished during cell division. During spermatogenesis in mammals, spermatocytes represent a long prophase of meiosis. The purpose of this work was to demostrate the possible variations in the amount of glycocalyx in isolated germinal cells during spermatogenesis differentiation.

Rat testes from 10, 23, and 38 days old, were finely scissored, in presence of Eagle essential medium, (mechanical treatment) Another similar group of isolated cells was treated with colagenase. (chemical treatment). Once separation of cells was completed, samples were treated for cytochemical electron microscopy using Alcian blue-lanthanum nitrate as previously described.