bluuebunny/crossref_metadata_2025 huggingface dataset:
Fine Structural Changes in the Microvasculature of the Mouse Pinna: Aging and Radiation Injury
Authors: Steamer S. Phyllis , Devine Rosemarie L.
Published: June 2020

The importance of radiation damage to the skin and its vasculature was recognized by the early radiologists. In more recent studies, vascular effects were shown to involve the endothelium as well as the surrounding connective tissue. Microvascular changes in the mouse pinna were studied in vivo and recorded photographically over a period of 12-18 months. Radiation treatment at 110 days of age was total body exposure to either 240 rad fission neutrons or 855 rad 60Co gamma rays. After in vivo observations in control and irradiated mice, animals were sacrificed for examination of changes in vascular fine structure. Vessels were selected from regions of specific interest that had been identified on photomicrographs. Prominent ultrastructural changes can be attributed to aging as well as to radiation treatment. Of principal concern were determinations of ultrastructural changes associated with venous dilatations, segmental arterial stenosis and tortuosities of both veins and arteries, effects that had been identified on the basis of light microscopic observations. Tortuosities and irregularly dilated vein segments were related to both aging and radiation changes but arterial stenosis was observed only in irradiated animals.
X-Ray Analysis Demonstrating the Ca Flux in the Gill Epithelium in Response to Drug and Electrical Stimulation
Authors: Paparo Anthony A. , Murphy Judith A.
Published: June 2020

Ciliated cell systems in bivalve molluscs may be individually controlled. The ciliary activity of the lateral cells depends on the "branchial nerve in Mytilus edulis. TEM has revealed direct contact "between nerve endings and lateral cells. Electrical stimulation of the branchial nerve increases the rate of beating of lateral cilia, probably by a mechanism involving release of 5-hydroxytryptamine(5-HT), which is cilioexcitatory. Continuous stimulation of the branchial nerve at frequencies higher than those used to obtain cilio-excitation led to cilioinhibition. A marked cilioinhibitory effect could be obtained with 3,4-dihydroxyphenylethylamine(DA).
Intramuscular Distribution of Calcium, Strontium, and Zinc Ions Following Intravascular Injection
Authors: Milhorat T. H. , Milhorat A. T. , Davis D. A.
Published: June 2020

Following injection into blood or cerebrospinal fluid, the intracerebral movement of calcium ion can be visualized by injecting a phosphate-containing fixative by the same route used for injecting calcium and viewing the resulting in vivo precipitate (calcium phosphate) with the electron microscope. In this study, the in vivo ion-precipitation technique has been used to localize the intramuscular distribution of intravascularly injected calcium, strontium, and zinc ions.
Stem of Hydrated Frozen Chick Fibroblast Monolayers
Authors: Germinario Louis T.
Published: June 2020

This report presents the first results obtained with the liquid nitrogen cooled cold stage for the JEM-100B operated in the STEM mode. The advantages of examining frozen biological specimens on a cold stage in this mode include: (a) considerably thicker specimens can be viewed since chromatic aberration is absent in the final STEM image, (b) for equivalent optical parameters both improved contrast and resolution in the STEM over CEM is by a factor of 3 or 4 at 100keV and 2 or 3 at 1MeV, (c) reduction of specimen contamination and damage due to the presence of residual hydrocarbons, water vapor, and heat generated from plasmon generation and ionization of the valance shell, (d) application of cryogenic techniques to specimen preparation eliminates the usual preparation artifacts, thus providing a lifelike image (frozen in state and time).
Chemical Composition of Microarthropods by Electron Microprobe Analysis; A. Preliminary Report
Authors: Todd R. L. , Crossley D. A. , Stormer J. C.
Published: June 2020

Investigations of nutrient circulation within the decomposer segment of a forest floor community have been aided by the use of an electron microprobe for the chemical analyses of these decomposer organisms. This report is a discussion of the application of this technique and presents a preliminary description of the calcium, potassium and magnesium data for several species of microarthropods.
Applications of Energy Dispersive Analysis on the Transmission Electron Microscope in Pathology and Pollution Studies
Authors: Barbi Nicholas C. , Russ John C.
Published: June 2020

Energy dispersive analysis on transmission electron microscopes has emerged during the past year as a highly useful analytical technique in Pathology and water and air pollution studies. The reasons for the immediate acceptance of the technique in these disciplines are that the xray sensitivity and spatial resolution provided in conventional TEM's are of the magnitude required for useful analysis and that interpretation of the analytical results is often straightforward. The following results presented or discussed were obtained on the Philips EM 300 and JEOL 1008 electron microscopes, operated at 60 or 80 kV.
Morphological Evidence for Protein Lesions in Chlamydomonas Photosynthetic Mutants
Authors: Kretzer Frank
Published: June 2020

Photosynthetlc point mutations in Chlamydomonas are single protein deletions or alterations which do not affect the gross morphology of the photosynthetlc apparatus. Thus, it is possible to study the effect of these mutations on membrane molecular structure at a 5A resolution in thin-sectioned material IF AND ONLY IF the membrane protein is not massively denatured during the process of fixation and dehydration. This resolution is superior to that obtainable with the freeze-etch technique.
Ultrastructural Investigations of the Contractile Filaments of Amoebae
Authors: Moore P.L.
Published: June 2020

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.

The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.
Ultrastructure of Giant Mitochondria and Their Inclusions in Schwann Cells of Bovine Splenic Nerve
Authors: Thureson-Klein Å.
Published: June 2020

Giant mitochondria of various shapes and with different internal structures and matrix density have been observed in a great number of tissues including nerves. In most instances, the presence of giant mitochondria has been associated with a known disease or with abnormal physiological conditions such as anoxia or exposure to cytotoxic compounds. In these cases degenerative changes occurred in other cell organelles and, therefore the giant mitochondria also were believed to be induced structural abnormalities.

Schwann cells ensheating unmyelinated axons of bovine splenic nerve regularly contain giant mitochondria in addition to the conventional smaller type (Fig. 1). These nerves come from healthy inspected animals presumed not to have been exposed to noxious agents. As there are no drastic changes in the small mitochondria and because other cell components also appear reasonably well preserved, it is believed that the giant mitochondria are normally present jin vivo and have not formed as a post-mortem artifact.
Anisopachous Cisternae and Cubic Lattice Structures in Hepatocytes of Rats Treated with Aminotriazole
Authors: Hruban Z. , Slesers A. , Gotoh M.
Published: June 2020

Administration of 3-amino-l,2,4-triazole (AT) decreases the activities of drug-metabolizing enzymes and inhibits the stimulation of the drugmetabolizing activities by the administration of phenobarbital (1). In the present study 1% AT in chow diet was fed ad libitum to young male Sprague-Dawley rats for 6 weeks. Thyroxin was given at 0, 0.5, 1.0, 1.5 and 2.0 ng per liter of drinking water. It was established that 1.0 mg thyroxin/L is adequate to prevent thyromegaly induced by AT.

Rats fed AT alone or with 0.5% acetylsalicylic acid for 6 weeks showed alterations of the endoplasmic reticulum in their liver cells. The hepatocytes contained variable amounts of conglomerates of the tubular smooth endoplasmic reticulum (Figs. 8, 9), some of which were less than 0.5 micron in diameter (Figs. 5, 6). The anastomosing tubules were more closely packed and the intertubular spaces were narrower when compared with tubular endoplasmic reticulum of normal hepatocytes.
Ultrastructural Study of Corneas Stored at Room Temperature
Authors: Van Horn D. L. , Pederson H. J.
Published: June 2020

Blindness due to loss of corneal transparency can often be corrected by corneal transplantation, however, the demand for donor tissue now exceeds the supply. Although there is little evidence to support the practice, most eye banks will not accept donor eyes unless they are removed from the cadaver within 6-8 hours after death and refrigerated. The purpose of this study was to determine if eyes can remain at room temperature longer than 8 hours before becoming unfit as donor material. Degenerative ultrastructural changes are described in the corneal epithelial, stromal and endothelial cells of eyes left in situ in cat cadavers at 22°C or removed and placed in sealed moist chambers at 22°C for various lengths of time.
Ultracytochemical Localization of Aryl Sulfatase, Esterase, and Acid and Alkaline Phosphatases with 4-Nitrocatechol Substrates and Tetrazolium Salts
Authors: Shannon W. Allen , Hoshino Yoshinobu , Wasserkrug Hannah L. , Seligman Arnold M.
Published: June 2020

The ultra cytochemical localization of various hydrolases, i. e, aryl sulfatase(ArS), esterase (Est), acid phosphatase(AcP) and alkaline phosphatase (A1P) is demonstrated in rat kidney cortex with newly developed 4-nitrocatechol substrates (2-hydroxy-5-nitrophenyl compounds) (Fig. 1) and tetrazolium salts, Nitro-BT, BSPT, and BPPT. ArS was also investigated in adrenal cortex.
The Growth of Herpesvirus mulatto in Human Fibroblast
Authors: Washington Glennelle , McGrath Philip P. , Graze Peter R. , Royston Ivor
Published: June 2020

Herpes-like viruses were isolated from rhesus monkey peripheral blood leucocytes when co-cultivated with WI-38 cells. The virus was originally designated rhesus leucocyte-associated herpesvirus (LAHV) and subsequently called Herpesvirus mulatta (HVM). The original isolations were from juvenile rhesus monkeys shown to be free of antibody to rhesus cytomegalic virus. The virus could only be propagated in human or simian fibroblasts. Use of specific antisera developed from HVM showed no relationship between this virus and other herpesviruses. An electron microscopic study was undertaken to determine the morphology of Herpesvirus mulatta (HVM) in infected human fibroblasts.
Virus Particles in Placenta and Uterus of RIII/Dm Strain Mice
Authors: Seman G. , Dmochowski L. , Hunter Sandra
Published: June 2020

Recent observation of type C virus particle synthesis in placenta of baboons and in human placenta has focused attention on the possible role of that organ in vertical transmission of oncogenic RNA viruses. Distribution of type C (murine leukemia) and type B (mouse mammary tumor) virus particles in some tissues of mice of strain RIII, a strain with high incidence of spontaneous mammary tumors (70%) and low incidence of spontaneous leukemia (3%) has been extensively studied by electron microscopy. However, their distribution in placenta and uterus of RIII mice has not been investigated so far.
Herpes Simplex Virus Superinfection of Mouse Cells Chronically Infected with Rausher Leukemia Virus
Authors: Andrese A. P. , Walling M. J. , Vande Woude G. F.
Published: June 2020

Although host-controlled fractors are known to alter biological properties of bacteriophage and animal viruses, little is known of the interaction between viruses themselves in a permissive host cell. Some biochemical and morphological evidence has accumulated associating both herpes virus and RNA tumor virus types as the etiological agents of Marek's disease in chickens. Further, Epstein-Barr herpesvirus, the agent associated with Burkitt's lymphoma in humans has been shown to contain RNA tumor virus-like particulate material with RNA-instructed DNA polymerase activity. The following study was initiated to determine the possible interaction of herpes simplex virus type-1 (HSV-1) and Rauscher leukemia virus (RLV) in a dually infected host cell.
Immune Electron Microscopy (IEM) of a Canine Adeno-Associated Virus
Authors: Thomas Gunter F. , Hoggan M. David
Published: June 2020

In 1968, Sugimura and Yanagawa described a small 25 nm virus like particle in association with the Matsuda strain of infectious canine hepatitis virus (ICHV). Domoto and Yanagawa showed that this particle was dependent on ICHV for its replication in primary dog kidney cell cultures (PDK) and was resistant to heating at 70°C for 10 min, and concluded that it was a canine adeno-associated virus (CAAV). Later studies by Onuma and Yanagawa compared CAAV with the known human serotypes (AAV 1, 2, 3) and AAV-4, known to be associated with African Green Monkeys. Using the complement fixation (CF) test, they found that CAAV was serologically related to AAV-3 and had wide distribution in the dog population of Japan.
Persistence of Nucleolar Material During Mitosis in Root Meristematic Cells of Allium sativum
Authors: Hanzely L.
Published: June 2020

Nucleoli are generally thought to be organelles lacking a continuity during cell division, i.e., they disperse during late prophase and reform within the daughter nuclei at telophase. Recently, however, nucleoli have been shown to persist during mitosis in several plant and animal species (e.g., references 1-4). In this report, evidence is presented indicating the persistence of nucleolar material throughout mitosis in root tip cells of Allium sativum.
Further Studies on the Ultrastructure of Harderian Gland in Adult Rats
Authors: Feria-Velasco Alfredo , Tapia-Arizmendi Guadalupe
Published: June 2020

The fine structure of the Harderian gland has been described in some animal species (hamster, rabbit, mouse, domestic fowl and albino rats). There are only two reports in the literature dealing on the ultrastructure of rat Harderian gland in adult animals. In one of them the author describes the myoepithelial cells in methacrylate-embbeded tissue, and the other deals with the maturation of the acinar cells and the formation of the secretory droplets. The aim of the present work is to analize the relationships among the acinar cell components and to describe the two types of cells located at the perifery of the acini.
Some Applications of the Berkeley 650 kV HVEM in Materials Science
Authors: Thomas Gareth
Published: June 2020

The applications of high voltage electron microscopy in materials science stem principally from the well known advantages of improved penetration, resolution, and benefits derived from multiple diffraction effects (e.g. critical voltage).

The principal disadvantages are the high costs, somewhat poorer resolution compared to the latest breed of 100 to 125 kV microscopes and for crystals it is necessary to operate at voltages below those which cause primary knockon damage, unless in situ studies of such damage are required.
Electron Microscopic Studies of Base Sequence in DNA
Authors: Beer Michael
Published: June 2020

I shall review the work on the electron microscopic determination of base sequence in DNA restricting myself to the approach in which one kind of base is selectively marked. The requirements for success are 1. Appropriate staining reaction: stain must be detectable yet sufficiently compact to allow resolution of adjaconts. Reactions must be sufficiently selective and sufficiently gentle to preserve the.polynucleotide chain. 2. Deposition of polynucleotide chains in untangled and sufficiently extended form. 3. Means for accurately enumerating unmarked bases between the marked ones.
Biogenesis of Smooth Endoplasmic Reticulum in Hepatocytes of Phenobarbital Treated Rats
Authors: Higgins Joan A.
Published: June 2020

In response to intraperitoneal injections of phenobarbital there is a marked proliferation of smooth endoplasmic reticulum membranes (s.e.r.) of rat hepatocytes, with little change in other membranous organelles. This increased membrane formation is accompanied by a rise in the specific activity of the enzymes involved in drug detoxification initially in the rough endoplasmic reticulum (r.e.r.) followed by a rise in the s.e.r. There is also an increased accumulation of glycerophospholipid in the newly formed s.e.r.
Immunocytochemistry. A Review of Methodology for Electron Microscopic Applicaiton
Authors: Mazurkiewicz Joseph E.
Published: June 2020

Immunocytochemistry is a powerful investigative approach in which one of the most exacting examples of specificity, that of the reaction of an antibody with its antigen, isused to localize tissue and cell specific molecules in situ. Following the introduction of fluorescent labeled antibodies in T950, a large number of molecules of biological interest had been studied with light microscopy, especially antigens involved in the pathogenesis of some diseases. However, with advances in electron microscopy, newer methods were needed which could reveal these reactions at the ultrastructural level. An electron dense label that could be coupled to an antibody without the loss of immunologic activity was desired.
Object Reconstruction from Micrographs. Two Dimensional Theory with Three Dimensional Outlook
Authors: Ferwerda H.A. , Hoenders B.J.
Published: June 2020

In this contribution we discuss the reconstruction of an object from one or more electron micrographs. We want to derive the locations and characters of the atoms which make up the object. Unfortunately inelastic scattering and multiple elastic scattering cannot reliably be related to the object structure because of the non-locality of these processes. The most promising starting point for object structure research therefore is single elastic scattering. This is a good approximation for thin objects and tends to become better fulfilled as the energy of the incident electrons increases. In that regime the weak object approximation, which is adopted here, also becomes more reliable because the phase shift and amplitude attenuation are decreasing functions of the energy (except in the neighborhood of resonances). In this approximation there is a linear relation between the intensity in the image plane and the object wavefunction. Object reconstruction for non-weak objects has been attempted but still is in its infancy.
The Quantitative Contrast Analysis of Weak-Beam Images
Authors: Villagrana R. E. , Horgen H. M. , Maher D. M.
Published: June 2020

The quantitative contrast analysis of a weak-beam image must proceed in three distinct phases: data collection, image enhancement, and image analysis. In this paper, we will discuss each of these phases in detail.

Data Collection: In order to perform a reasonable contrast analysis, one must know the specimen thickness, the depth dependence of the defect, and the diffraction conditions. In regard to the diffracting conditions, we must point out that accurate contrast calculations can only be made for the excitation of systematic reflections. Finally, three micrographs of the image to be analyzed are needed for image enhancement.
Some Principles of Many-Beam Image Computations for Defective Crystals
Authors: Nakahara S. , Maher D. M. , Thomas L. E. , Fisher R. M.
Published: June 2020

Rapid computational techniques for obtaining two-beam, computer displayed images of inclined straight dislocations and stacking faults have been given, respectively, by Head and Humble. Their computational techniques are based on two principles, namely, the generalized cross section (GCS) and linear combination (LC) of wave amplitudes. The first of these principles is a consequence of the plane stress and/or plane strain nature of the defects they considered whereas the second principle follows directly from linearity of the two-beam dynamical equations assuming the validity of the column approximation. in this paper the concept of an expanded column (EC) is introduced and it is shown that if the column approximation is assumed then the LC of wave amplitudes is a valid and important principle when calculating many-beam, image intensities for a general defect in an infinite medium.
Imaging and Contrast of Crystal Defects in High Voltage Transmission Scanning Electron Microscopy
Authors: Nishizawa H. , Shibatomi K. , Yamamoto T.
Published: June 2020

There is now a progress in the imaging of crystal defects in the STEM. The image contrast of the defects in the STEM depends on the diffraction condition as similarly in the CTEM. There is, however, a significant difference between CTEM and STEM; the aperture angle of illuminating beam in the latter is quite large. In this report, the relationship between the STEM image and the following conditions was extensively studied with a scanning transmission electron microscope JSEM-200 equipped with a side entry goniometer at 200kV; illuminating angle (2αi), collecting angle (2αc) and positioning θc of an aperture selecting an angular direction of a diffraction spot.
Stereoscopic Analysis of Irradiation-Induced Voids
Authors: Thomas L. E. , Lentz S.
Published: June 2020

Radiation-induced swelling due to void formation, found in most materials after exposure to the high temperatures (400-750 C) and fluences (1022-1033 neutrons/cm2 having energies >MeV) of a liquid-metal fast-breeder reactor, is often studied on a laboratory time scale in specimens bombarded with electrons or with energetic ions. The voids, along with dense arrays of dislocations, arise by selective agglomeration of thermally mobile point-defects (vacancies and interstitials) created by any radiation sufficiently energetic to displace atoms from crystal lattice sites. Both of these simulation methods produce voids that are distributed non-uniformly in depth within a few ym of the bombarded surface, so that careful sectioning or analysis is required to relate the observed defect structures to the swelling characteristic of bulk material.
Single Atom Image Contrast in Fixed Beam Dark Field Electron Microscopy
Authors: Chi Wah
Published: June 2020

Resolution and contrast are the important factors to determine the feasibility of imaging single heavy atoms on a thin substrate in an electron microscope. The present report compares the atom image characteristics in different modes of fixed beam dark field microscopy including the ideal beam stop (IBS), a wire beam stop (WBS), tilted illumination (Tl) and a displaced aperture (DA). Image contrast between one Hg and a column of linearly aligned carbon atoms (representing the substrate), are also discussed. The assumptions in the present calculations are perfectly coherent illumination, atom object is represented by spherically symmetric potential derived from Relativistic Hartree Fock Slater wave functions, phase grating approximation is used to evaluate the complex scattering amplitude, inelastic scattering is ignored, phase distortion is solely due to defocus and spherical abberation, and total elastic scattering cross section is evaluated by the Optical Theorem. The atom image intensities are presented in a Z-modulation display, and the details of calculation are described elsewhere.
A Comparison of Calculated Images Generated by Six Modes of Transmission Electron Microscopy
Authors: Engel A. , Wiggins J. W. , Woodruff David
Published: June 2020

Six modes of transmission electron microscopy are compared by a numerical simulation of the image formation assuming perfectly coherent illumination and ignoring the influence of radiation damage and noise. The comparison includes five modes of conventional electron microscopy (CEM): axial bright field, Unwin's phase plate, central stop dark field, tilted-beam dark field and conical illumination dark field, and the annular detector mode of the scanning transmission electron microscope (STEM).
Measurements of the Non-Local Nature of the Inelastic Scattering of Electrons in Carbon
Authors: Isaacson M. , Langmore J. , Rose H.
Published: June 2020

The STEM offers the possibility of utilizing all inelastically scattered electrons for image formation. Inelastic scattering, however, is a nonlocalized interaction due to the electron-electron correlation occurring predominantly at the edge of the atomic electron cloud. Therefore, not all inelastically scattered electrons carry high resolution spatial information about the specimen.
Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun
Authors: Harada Y. , Goto T. , Koike H. , Someya T.
Published: June 2020

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.
A 150 kV High-Coherence Microscope
Authors: Worsham R. E. , Harris W. W. , Mann J. E. , Richardson E. G. , Ziegler N. F.
Published: June 2020

Welton has shown that if the illuminating beam in a conventional transmission microscope column has a transverse coherence length of 5°0 Å, or greater, and an energy spread ≤0.2 eV(rms), spatial information at the 0.5 Å resolution level would be attenuated by a factor of 2 and 1 Å information essentially unimpaired. The untreated micrographs, which would show a complex set of fringes with detail down to about 2.5 Å as set by spherical aberration, would require the application of a Wiener filter function to bring out the existing finer details. This microscope was designed to produce the high coherence required, to permit this method of correction for the spherical aberration, and to be limited in no other way in resolution down to <1Å.
Surface Studies with Medium Energy Electron Diffraction (MEED)
Authors: Albain J. L. , Cowley J. M. , Højlund Nielsen P. E. , Koch F. A. , Shuman H.
Published: June 2020

The development of an instrument using MEED for surface studies has continued In our laboratory. The instrument was described at the last EMSA meeting. In order to examine the specimen in the available voltage range (0.8-15 keV) a magnetic lens was introduced, so the beam could be focussed at the surface. For examining different sections of the surface deflection coils were added. An over-all view of the present stage of the instrument is given in fig. 1. The specimens are usually cleaned in situ by means of an ion gun and electron heating gun. The contamination of the surface is still a problem even though the operation pressures are in the low 10-8 torr region. A gas handling system has been added in order to perform oxidation studies in situ and to introduce argon for ion-bombardment of the specimen.
An Energy Analyser for Contrast Enhancement in STEM
Authors: Pearce-Percy H.T.
Published: June 2020

Recently an energy analyser of the uniform magnetic sector type has been installd in a 100KV microscope. This microscope can be used in the STEM mode. The sector is of conventional design (Fig. 1). The bending angle was chosen to be 90° for ease of construction. The bending radius (ρ) is 20 cm. and the object and image distances are 42.5 cm. and 30.0 cm. respectively.
Ion Thinning of Electron Transparent Single Crystal Sapphire Substrates
Authors: Kenty J. L. , Johnson R. E.
Published: June 2020

Samples of single crystal sapphire (α-Al2O3) have been ion-beam thinned to yield electron transparent regions suitable for use as substrates for in situ thin film growth experiments. Routine fabrication of 1 mm dia. samples containing one or more thin (∼200Å) regions ∼10μm2 in area was possible. The samples were surprisingly robust, many surviving post-thinning subdivision, mounting into a TEM environment cell, and heating to ∼1200°C.
Lorentz Electron Microscopy of Magnetic Domains in Eptaxial Iron Films
Authors: Lawless K. R. , Proto G. R.
Published: June 2020

This paper describes the results of a study of domain walls in single crystal iron films by Lorentz electron microscopy. The films were prepared by evaporating 99.99% iron wire onto an air cleaved (100) rock salt substrate heated to 400°C. The films were stripped from the rock salt, mounted on Cu folding grids and annealed at a temperature between 700°C and 900°C. The study was performed in a Siemens Elmiskop 1 A operated in the weak field objective lens mode with the specimen raised 5.4 mm. above its normal operating position.
Stripping Metal Oxide and Fluoride Films with Elemental Iodine
Authors: Bartlett T. W.
Published: June 2020

A variety of techniques can be used to remove oxide or fluoride films from metals prior to examination in the electron microscope. Particularly well known are techniques utilizing electrolysis in a saturated potassium chloride solution, and treatment with iodine in either a methanol solution or as iodine dissolved in aqueous potassium iodide. The method described here is particularly simple and is well suited to the investigator with only an occasional need to examine corrosion films. The method requires no unusual equipment, it requires very little attention, and it is applicable to a variety of metals.
Properties of the Interference Function for Unbent, Spherically, and Cylindrically Bent Lattices
Authors: Güven Necip
Published: June 2020

Kinematical diffraction effects from thin crystalline films may be readily explained in terms of the interference function (ϕ). For an undeformed and orthogonal lattice:

It can be shown that this function is independent of reciprocal and real cell parameters. It is dependent only on the number of lattice planes in a given direction and on the distance from a reciprocal lattice point. Furthermore, this function is symmetrical at each reciprocal lattice point.
Influence of Heat Treatments on Microstructures in an Fe-Co-V Alloy
Authors: Mahajan S. , Pinnel M. R. , Bennett J. E.
Published: June 2020

The microstructural changes in an Fe-Co-V alloy (composition by wt.%: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single phase ϒ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Figure 1 shows dislocation topology in a region that may have transformed martensitically. Dislocations are homogeneously distributed throughout the matrix, and there is no evidence for cell formation. The majority of the dislocations project along the projections of <111> vectors onto the (111) plane, implying that they are predominantly of screw character.
Pollutant Identification by Selected Area Electron Diffraction
Authors: Ferrell R. E. , Paulson G. G. , Walker C. W.
Published: June 2020

Selected area electron diffraction (SAD) has been used successfully to determine crystal structures, identify traces of minerals in rocks, and characterize the phases formed during thermal treatment of micron-sized particles. There is an increased interest in the method because it has the potential capability of identifying micron-sized pollutants in air and water samples. This paper is a short review of the theory behind SAD and a discussion of the sample preparation employed for the analysis of multiple component environmental samples.
Analysis of Airborne Particles with Particular Emphasis on Automobile Exhausts
Authors: Grieger Gene R.
Published: June 2020

The size range of exhaust emissions from automobiles tends to be below the limit of resolution of the light microscope. There is at the present time considerable interest in the particulate emissions from automobiles both using leaded and unleaded gasoline and in particular there is interest in modifications to thes-e emissions which may occur for example by the use of catalytic converters in exhaust systems.
Bimodal Crystal Texture in Polypropylene
Authors: Andersen Paul
Published: June 2020

The morphology of polypropylene frozen while undergoing flow is vastly different from the quiescent crystallized material (pictures 1 and 2). As a result of flow-crystallization, polypropylene exhibits a new set of useful properties. Since direct observation studies of the important flow-crystallized structure are incomplete, the objective of this study was to characterize and obtain a better understanding of the nature of the two crystallite population (bimodal) structure in flow-crystallized polypropylene.
Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals
Authors: Bolz L.H. , Reneker D.H.
Published: June 2020

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.
Transfer Technique for Electron Microscopy of Membrance Filter Samples
Authors: Ortiz Lawrence W. , Isom Bonnie L.
Published: June 2020

A procedure is described for the quantitative transfer of fibers and particulates collected on membrane filters to electron microscope (EM) grids. Various Millipore MF filters (Millipore AA, HA, GS, and VM; 0.8, 0.45, 0.22 and 0.05 μm mean pore size) have been used with success. Observed particle losses have not been size dependent and have not exceeded 10%. With fibers (glass or asbestos) as the collected media this observed loss is approximately 3%.
Chemical Species Identification in an SEM by Changes in Emitted X-Ray Energies
Authors: Duff R. H.
Published: June 2020

A material irradiated with electrons emits x-rays having energies characteristic of the elements present. Chemical combination between elements results in a small shift of the peak energies of these characteristic x-rays because chemical bonds between different elements have different energies. The energy differences of the characteristic x-rays resulting from valence electron transitions can be used to identify the chemical species present and to obtain information about the chemical bond itself. Although these peak-energy shifts have been well known for a number of years, their use for chemical-species identification in small volumes of material was not realized until the development of the electron microprobe.
A Critique of the Theoretical Basis for the Use of Hvem in Biology
Authors: Glaeser Robert M.
Published: June 2020

Just as the term “high voltage” has no unique definition in electron microscopy, so too the advantages of higher voltages are relative and a matter of degree, rather than absolute and without comparison. The advantages that are associated with higher voltages derive from the physical characteristics of high energy electrons, which necessarily vary in a continuous fashion as the energy increases. It is useful to distinguish between those voltage-dependent characteristics that allow one to use progressively thicker specimens, for the same “image quality”, and those characteristics that can give improved image resolution, for the same specimen thickness. In the present critique only the suitability of using high voltage for thicker biological specimens will be discussed, since experimental work that takes advantage of the higher resolution capabilities has not yet been practical with biological specimens. In the following it will be assumed that the limiting factors in image resolution are due to staining and other aspects of specimen preparation, and also to radiation damage, rather than the instrumental resolving power.
High Voltage Electron Microscopy of Muscle Using Thick Slices of Embedded Tissue and Selective Stains
Authors: Peachey Lee D.
Published: June 2020

One way to take advantage of the increased penetrating power of the high energy electrons in a high voltage electron microscope for the study of biological cells and tissues is to examine thicker sections or slices of embedded tissues. Whereas a thickness of 0.1 micrometers usually is considered to be the useful limit on section thickness for electron microscopy at 100 kV, one can reasonably expect this limit to be increased ten-fold when using accelerating voltages in the range of 1000 kV. In fact, experience has shown that one can go considerably beyond this in thick ness and still get images that are useful for biological analysis. The examination of slices of tissues up to several micrometers thick offers clear advantages over the study of thinner sections in the elucidation of three-dimensionals tructure. This approach can be contrasted to the study of whole cell mounts, as discussed in other papers in this symposium. Whole cells usually are examined after critical point drying, without embedding. Such specimens, suspended in a vacuum, present little problem with respect to contrast. Embedded and sectioned tissues, however, are suspended in a plastic embedding material, which itself has considerable electron scattering power. Therefore, unless the tissue elements are well stained relative to the surrounding embedding material, their visibility and contrast can be insufficient for useful and interpretable images, especially in thick slices.
Mechanisms for the Incorporation of Proteins into Mfmrrames
Authors: Sabatini David D.
Published: June 2020

Secretory polypeptides appear to be invariably synthesized on membrane bound ribosomes and cotranslationally inserted into the lumen of endoplasmic reticulum (ER) cisternae. Synthesis on bound polysones appears to be also the f i r s t step in the biosynthesis of lysosonal hydrolases. On the other hand, polypeptides to *e incorporated as integral components into cellular membranes may be synthesized either in bound polysomes and inserted into the FP membranes cotranslationally, or in polysomes free in the cytoplasm and incorporated into the phospbolipid bilayer by posttranslational mechanisms. We have found examples of both types of membrane polypeptides in the FR, as well as the plasna membrane.
Involvement of CA++ and Calmodulin in the Intracellular Migration of Influenza's Hemagglutinin to the Apical Surface of MDCK Cells
Authors: Rodriguez-Boulan E. , Paskiet K.T. , Bard E.
Published: June 2020

The polarized distribution of surface components between apical and basolateral domains of the plasma membrane constitutes the basis of epithelial function. We are currently studying the mechanisms employed by epithelial cells to segregate different sets of integral proteins in two opposite regions of the plasma membrane. For this purpose, we are utilizing a model system which involves the infection of polarized epithelial cell lines, such as the dog kidney cell line MDCK, with enveloped RNA viruses. Influenza virus and two paramyxoviruses bud from the apical surface regions of MDCK cells, vesicular stomatitis virus (VSV), a rhabdovirus, is assembled instead from the basolateral surface. A main determinant of polarized budding appears to be the addressing of viral envelope glycoproteins to the surface domain that the virus utilizes for budding. The mechanisms and intracellular pathways involved in this sorting are probably the same as those utilized by the cell for its own surface proteins.
ATP-Citrate Lyase Localized with the Peroxidase-Antiperoxidase Technique in RAT Heart and Liver
Authors: Shannon W.A. , Chang C.S. , Bates S.B.
Published: June 2020

Enzyme kinetic data has indicated the probability of “soluble” enzymes existing in situ as macromolecular complexes. These enzymes often function in sequential reactions, e. g., mitochondrial Krebs cycle. Therefore, it is important to define morphologically their functional in situ localization. One such enzyme of interest is ATP-citrate lyase (citrate cleavage enzyme). Biochemically, it has been characterized as a cytoplasmic enzyme. However, there are teleological as well as other indications that it may be concentrated in the vicinity of mitochondria.
Thin Section Staining of Epithelial Cells to Reveal Bound Carbohydrate
Authors: Marenus K. , Beer M.
Published: June 2020

A complex of OsVIin combination with the ligand TEMED(Tetramethylethylenediamine) has been shown to be specific for glycol groups of sugar. This stain has been successfully applied to thin sections: The same staining patterns were revealed in type 1 collagen in both isolated and embedded material (Fig.1). Special embedding techniques designed to minimize the perturbation of the specimen were required. In the present preliminary study these methods (and the specific stain) have been applied to thin sections of epithelial cells and have given information on the intracellular distribution of bound carbohydrates. Other methods for investigations of this nature are at lower resolution and do not allow for discrimination of sugars at membrane surfaces of closely adjacent organelles.
Image Processing of Imperfect Protein Arrays: Sectioned CRYSTALS and Tubulin Sheets and Rings
Authors: Crepeau Richard H. , Fram Evan K. , McEwen Bruce , Akey Christopher W. , Pantaloni Dominique , Szalay Margot , Edelstein Stuart J.
Published: June 2020

The advent of low dose electron microscopy has placed emphasis on the minimization of electron beam damage in either stained or unstained samples. This results in lower signal to noise ratios and averaging techniques must be employed to achieve the goal of high resolution imaging. The large number of unit cells required severely limits the number of macromolecular species that can be analyzed by conventional image processing techniques relying on perfect order (DeRosier & Klug, 1972). Between the randomly oriented single particles analyzed by Frank et al. (1978) and perfect arrays there is a vast category of materials possessing only approximate symmetries due either to sample preparation techniques or in the case of high resolution unstained work to microscope limitations (Hayward & Stroud, 1981). We discuss here three important classes of ordered structures that may be analyzed even though the symmetries present are only approximate: (1) Rotationally symmetric objects are analyzed by an interactive rotational power spectrum technique that will be demonstrated on micrographs of tubulin rings formed in the presence of magnesium (Voter & Erickson, 1979) and embedded and sectioned microtubules.
In Vivo Microtubule Assembly/Disassembly States in Reticulopods of Allogromia SP
Authors: Koury Stephen T.
Published: June 2020

Ultrastruetural changes occur during retraction of the reticulopodial network(RN) of the marine foraminiferan Allogromia sp.(strain N.F. Lee) after induction by varied experimental stimuli. The normally active RN (Fig. 1) emerges from the cell body(CB) and radiates over long distances, exhibiting bidirectional streaming of particles throughout. The normal, untreated RN cytoskeleton contains microtubules(MT). 5nm filamente(F), and helical filaments(HF), which are probably derived from MT by uncoiling. Helical filaments may aggregate to form paracrystals(PC). We originally, and others subsequently have proposed tubulin packaging to facilitate rapid transport and/or storage. Retraction in Allogromia is a state in which rapid transport of cytoskeletal proteins is essential. We have evidence that suggests packing of helical filaments may fulfill this role. See fig. 2.
The Ultrastructure of the Distal Tubule of Amphiuma: A Tem and Sem Study
Authors: Biemesderfer D. , Stanton B. , Kashgarian M. , Giebisch G.
Published: June 2020

Although the surface distal tubule of Amphiuma means has been used in transport and electrophysiology studies, a detailed description of its ultrastructure is lacking. In vitro microperfusion studies have identified three physiologically distinct segments. This study describes the morphology of the distal tubule of Amphiuma by transmission and scanning electron microscopy.

Kidneys of ten animals were perfused via the aortic and portal vessels with amphibian ringers followed by fixative containing 1% paraformaldehyde, 1.25% glutaraldehyde, 0.05 M sucrose, 2% T40 Dextran, in 0.05 M Na cacodylate buffer, pH 7.2. For TEM, the kidneys were processed as described previously. For SEM, the tissue was osmicated, dehydrated and critical point dried using CO2
Human Neurofibromas in Co-Culture with Mouse Neurons
Authors: Martuza R.L. , Liszczak T. , Okun A. , Wang T-Y
Published: June 2020

Neurofibromatosis (NF) is an autosomal dominant genetic disorder with a prevalence of 1/3,000 births. The NF mutation causes multiple abnormalities of various cells of neural crest origin. Schwann cell tumors (neurofibromas, acoustic neuromas) are the most common feature of neurofibromatosis although meningiomas, gliomas, and other neoplasms may be seen. The schwann cell tumors commonly develop from the schwann cells associated with sensory or sympathetic nerves or their ganglia. Schwann cell tumors on ventral spinal roots or motor cranial nerves are much less common. Since the sensory neuron membrane is known to contain a mitogenic factor for schwann cells, we have postulated that neurofibromatosis may be due to an abnormal interaction between the nerve and the schwann cell and that this interaction may be hormonally modulated. To test this possibility a system has been developed in which an enriched schwannoma cell culture can be obtained and co-cultured with pure neurons.
The Vestibular Nerve and Ganglia of the Squirrel Monkey after Labyrinthectomy
Authors: Fermin C. D. , Igarashi M.
Published: June 2020

Since Nissl's observations in 1894, it is known that after injury, peripheral nerves undergo morphological and physiological modifications of their axons, dendrites and soma (perikarya) that cause the nerve to degenerate (Wallerian degeneration). The ultrastucture of vestibular ganglia (Scarpa) have been studied in various species including man, and its neuroanatomical relationship to the vestibular nuclei has also been studied. Histological work has shown that the squirrel monkey vestibular ganglia (SMVG) can survive after labyrinthectomy. The squirrel monkey (saimiri sciureus) is a small primate that is intensively used in otological research, however, only a few studies have examined the SMVG ultrastructurally. Here we present the results from our first study intended to ellucidate the pathology of the surviving SMVG following injury to the peripheral end organs and nerves.