bluuebunny/crossref_metadata_2025 huggingface dataset:
Image Enhancement, Micrograph Screening, and Teaching Principles of Contrast with a High Resolution Closed Circuit Television System
Authors: Cohen Arthur L. , Steever R.G.E.
Published: June 2020

For several years we have been using a closed circuit television system consisting of a high resolution camera (1000 lines), monitor, mount, incident lighting for prints, a light box for negatives with cooling fan and silicon controlled rectifier (SCR) for controlling light intensity. This assembly (Fig. 1) has the following controls: spatial inversion (right-left, top-bottom), image inversion (negative-positive), image height and width, brightness, and contrast. Other image controls (gain, target, pedestal) are infrequently needed. Contrast and tonal range may be widely varied; negatives may be viewed as positives, distortion (as in scanning microscopy) may be corrected, and image size may be adjusted.

The system is useful for: (1) Screening negatives for suitability of print ing by displaying them as positives (i.e. simulated prints) thus obtaining an idea of the degree of contrast desired. (2) Extracting the maximum information from a negative.
Electron Beam Microfabrication Systems
Authors: Broers Alec N.
Published: June 2020

Integrated circuit components are built into single crystal semiconductor wafers by a series of processes which use patterned resist layers. Images are normally formed in the resist layers by exposure to ultraviolet (UV) light through a contact mask. The minimum features that can be formed with this method are about 2.5μ in size. Devices with smaller dimensions however, are faster, and potentially cheaper because more of them can be built into a single wafer. Considerable effort has therefore been expended on improving the resolution and reliability of the image forming process. Electron beam, x-ray and UV methods are all being explored and each method offers unique advantages. This paper briefly describes the two basic electron beam methods; scanning and image projection. A fuller description of novel lithography processes, and a more complete set of references has been given by the author elsewhere. (Proc. Electron & Ion Beam Conf., Wash., D. C. (1976)).
Experimental High Resolution Dark Field Electron Microscopy
Authors: Pierce Larry , Buseck Peter R.
Published: June 2020

High resolution dark field (DF) images of the superstructures of the pyrrhotite (Fe1-xS) and bornite-digenite (Cu5FeS4-Cu9S5) series can be related to structure. Further, they provide more detail than bright field (BF) images. The same objective aperture size and stigmater settings were used for DF as for BF imaging; symmetrical arrangements of diffracted beams in the objective aperture were used. Images that can be related to structure were obtained at the defocus value giving the greatest image contrast, thereby enabling proper defocusing without requiring extensive through-focus series.

For the minerals of interest, diffraction patterns consist of many superstructure reflections and a few subcell reflections. BF images contain primarily features of the superstructure, presumably because the subcell reflections fall far from the axis of the objective lens and thus are affected by spherical and chromatic aberrations and beam divergence. Likewise, DF images formed with a similar arrangement of beams as that in BF contain only features of superstructure, but with reverse contrast to BF.
Combined Analytical And High Resolution Microscopy - A Case Study
Authors: Geiss R. H. , Clarke D. R.
Published: June 2020

The rapid development of n ew metallic and ceramic alloys is making greater demands of our materials characterisation techniques and increasingly when looking at a microstructure we need to know the answers to the following types of questions: a) what are the crystal structures of the constituent phases and inclusions?; b) what are their elemental compositions?; c) is that minor phase crystalline or amorphous?; d) has an element segregated? What is more we need to know this information from all the phases, even the very smallest. Hot-pressed silicon nitride fluxed with yttrium oxide is an example of a newly developed material and we have used it as a case study to determine the capabilities of commercially available equipment for materials characterization. Specifically, we have used a combination of rocking beam micro-diffraction, high resolution dark field imaging, x-ray microanalysis, lattice fringe imaging and D stereo-microscopy to investigate the material. The results of such a comprehensive characterization and the limitations experienced will be described in the presentation.
Characterization Of Chrysotile Asbestos In Automobile Brake Drum Dust By Transmission Electron Microscopy (TEM)
Authors: Seshan Krishna , Smith Glenn R.
Published: June 2020

This study supports other work that automobile brake drum dust is a source of partially altered and unaltered chrysotile asbestos (1-3) and suggests that dark-field electron microscopy could be used to identify the source of the fibres. These results are in contradiction to those who report that high temperatures reached during braking reduce a majority of the chrysotile to forsterite (4,5).

Automobile brake drum dust was directly transferred to formvar coated grids and coated with carbon on both sides. The grids were then examined with a Siemens 1A and a Philips 301 at 100 kV.

Intact chrysotile fibre bundles with some phenolic opaque binder is shown in Fig. 1 displaying partially deformed internal canals, but does not show gross morphological change. Unaltered chrysotile is shown in Fig. 2a and was confirmed by selected area electron diffraction (SAED), see Fig. 2.
Beam Enhanced Oxidation Of Fe-20%A1 In A Transmission Electron Microscope
Authors: Dahmen Ulrich
Published: June 2020

In spite of the common use of high voltage electron microscopy for studies of radiation damage in metals, the effect of a conventional 100 kV electron beam on the morphology and diffraction phenomena of thin metal foils has been widely neglected. The present paper calls attention to the importance of beam enhanced oxidation as a source of serious misinterpretation of electron micrographs. A variety of techniques of electron microscopy will be used to demonstrate the growth and morphology of oxides on thin foils. Although this study is limited to FeAl, spontaneous or beam enhanced oxidation are observed in a number of systems (1,2).

Figure 1 shows a high density of small domains that have grown in the limited area exposed to the beam. These domainsocan be identified as an fee oxide phase with a lattice parameter of ∽8.1Å, in epitaxy with the matrix. The observed orientation relationship is of the Nishiyama- Wassermann type (3).
Trends in Electron Energy Loss Spectroscopy
Authors: Colliex C. , Trebbia P.
Published: June 2020

The physical foundations for the use of electron energy loss spectroscopy towards analytical purposes, seem now rather well established and have been extensively discussed through recent publications. In this brief review we intend only to mention most recent developments in this field, which became available to our knowledge. We derive also some lines of discussion to define more clearly the limits of this analytical technique in materials science problems.

The spectral information carried in both low ( 0<ΔE<100eV ) and high ( >100eV ) energy regions of the loss spectrum, is capable to provide quantitative results. Spectrometers have therefore been designed to work with all kinds of electron microscopes and to cover large energy ranges for the detection of inelastically scattered electrons (for instance the L-edge of molybdenum at 2500eV has been measured by van Zuylen with primary electrons of 80 kV). It is rather easy to fix a post-specimen magnetic optics on a STEM, but Crewe has recently underlined that great care should be devoted to optimize the collecting power and the energy resolution of the whole system.
Data Acquisition and Handling Unit for a Quantitative Use of Electron Energy
Loss Spectroscopy
Authors: Trebbia P. , Ballongue P. , Colliex C.
Published: June 2020

An effective use of electron energy loss spectroscopy for chemical characterization of selected areas in the electron microscope can only be achieved with the development of quantitative measurements capabilities.

The experimental assembly, which is sketched in Fig.l, has therefore been carried out. It comprises four main elements.

The analytical transmission electron microscope is a conventional microscope fitted with a Castaing and Henry dispersive unit (magnetic prism and electrostatic mirror). Recent modifications include the improvement of the vacuum in the specimen chamber (below 10-6 torr) and the adaptation of a new electrostatic mirror.

The detection system, similar to the one described by Hermann et al (1), is located in a separate chamber below the fluorescent screen which visualizes the energy loss spectrum. Variable apertures select the electrons, which have lost an energy AE within an energy window smaller than 1 eV, in front of a surface barrier solid state detector RTC BPY 52 100 S.Q. The saw tooth signal delivered by a charge sensitive preamplifier (decay time of 5.10-5 S) is amplified, shaped into a gaussian profile through an active filter and counted by a single channel analyser.
Practical Materials Microanalysis by Electron Spectrometry
Authors: Joy David C. , Maher Dennis M.
Published: June 2020

Electron energy loss spectrometry (EELS) is the study of the inelastic scattering events which an electron undergoes during its passage through a sample. When an analysis of the elemental constituents of the specimen is required the most important inelastic events are the ionizations of inner shells of the atom since these cause discontinuities ("edges") in the EEL spectrum at energies which are charactertistic of the element concerned. A simple electron spectrometer combined with an electron microscope makes it possible to use this information for sensitive elemental identification and localization for all elements above Lithium. The EELS can thus be regarded as an adjunct to the more conventional energy dispersive X-ray spectrometer (EDS), which is restricted to elements above Magnesium. This paper discusses the necessary parameters of a EEL spectrometer designed for materials microanalysis, its coupling to the microscope and the basic techniques of data collection and analysis.
Suppression of γ’ Precipitation in a Laser-Melted Nickel-Base Alloy
Authors: Walsh J. M. , Whittles J. C. , Kear B. H. , Breinan E. M.
Published: June 2020

Conventionally cast γ’ precipitation hardened nickel-base superalloys possess well-defined dendritic structures and normally exhibit pronounced segregation. Splat quenched, or rapidly solidified alloys, on the other hand, show little or no evidence for phase decomposition and markedly reduced segregation. In what follows, it is shown that comparable results have been obtained in superalloys processed by the LASERGLAZE™ method.

In laser glazing, a sharply focused laser beam is traversed across the material surface at a rate that induces surface localized melting, while avoiding significant surface vaporization. Under these conditions, computations of the average cooling rate can be made with confidence, since intimate contact between the melt and the self-substrate ensures that the heat transfer coefficient is reproducibly constant (h=∞ for perfect contact) in contrast to the variable h characteristic of splat quenching. Results of such computations for pure nickel are presented in Fig. 1, which shows that there is a maximum cooling rate for a given absorbed power density, corresponding to the limiting case in which melt depth approaches zero.
Electron Microscopic Observations of Deformation Substructures in Polycrystalline Titanium Containing Rare-Earth Additives
Authors: O'Neal J. E. , Lederich R. J. , Sastry S. M. L.
Published: June 2020

The addition of small amounts of erbium to titanium results in a uniform dispersion of 20-60 nm diam particles in the Ti matrix. The presence of such fine dispersoids effects significant grain-refinement and grain-growth- retardation at elevated temperatures (1). Results of a thin-foil, transmission-electron-microscopic study of the influence of Er dispersoids on the development of dislocation substructure during tensile deformation are reported here.

Figure la shows the dislocation arrangement in Ti-O.lEr deformed at 293 K to a strain ≈ 0.40. The structure consists of well-defined cells, with the cell walls aligned parallel to  directions. The average spacing of cells in the  directions is ≈ 0.5 μm. Dispersoids are located both at the cell boundaries (as at A in Fig. la) and within the cells (as at B). Dis- persoid-free Ti that is similarly strained develops a coarser cell structure with an average cell spacing ≈ 1 μm (Fig. lb).
Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction
Authors: Gulik-Krzywicki T. , Costello M.J.
Published: June 2020

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.

Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.
Structural Changes Leading to Spore Formation in the Myxosporidian Parasite Ceratomyxa Shasta Nobel
Authors: Yamamoto T. , Silliphant R.L.
Published: June 2020

Ceratomyxa shasta is a myxosporidian effecting mortalities of various species of salmonidae along the western regions of the North American continent.1,2 It is generally accepted from studies of myxosporidian infected t i ssues that the trophozoi tes undergo hi stozoi c development into multi- nucleated complexes which eventually form 2 characteristic spores in the mother cell. Most of the studies of Ceratomyxa have been with the light microscope3 and because of the small size of the parasite much of the structural details were not evident.

For the electron microscopic analysis of the sporont and the developing spore of C. shasta two sources of experimentally infected specimens were examined. These were thin sections of free floating developmental forms from the gall bladder and thin sections of intestinal caecae fixed at 2, 7, 14 and 21 days following infection. The trophozoites measuring 20 μm in diameter were observed to increase in number by 14 days, infecting the connective tissue layer between the intestinal epithelial mucosa and the muscularis layer.
Human Karyotype as Seen by Scanning Electron Microscopy of Smeared Lymphocytes
Authors: Gettner Mark E. , Ledbetter Myron C. , Woods Philip S.
Published: June 2020

Our objective is to take advantage of the resolving power of the scanning electron microscope (SEM) to study details of karyotype morphology for which the light microscope is limited. To the best of our knowledge the SEM has not been used to study karyotypes. To demonstrate the feasibility of this, we chose initially to examine a standard method used in light microscopy, namely the Carnoy-fixed peripheral lymphocyte chromosome technique that has found such universal favor (1), and to modify it for SEM observation. Methods were devised to permit observation and indexing by light microscopy prior to SEM observation. We report here our preliminary results using cells smeared on subbed slides then osmium ligated, and cells smeared on aluminum coated glass without metal staining. Both types of preparations were Giemsa stained and were observed uncoated.
Ultrastructure of Isolated Mitochondria from the Renal Cortex after Reversible and Irreversible Ischemia in the Rat
Authors: Coleman S. E. , Duggan J. , Hackett R. L.
Published: June 2020

Complete renal ischemia causes a series of subcellular changes including chromatin clumping, dilation of endoplasmic reticulum and condensation of mitochondrial matrix followed by swelling of the mitochondria and unfolding of the cristae (1). Most mitochondria are condensed by 15 minutes and half are condensed and half swollen by 30 minutes with the majority of the mitochondria swollen by 60 minutes of ischemia.

In this study we have looked at the ability of mitochondria isolated from ischemic rat kidneys to undergo structural energy transformations in the presence of substrate and ADP. Mitochondria were isolated from the inner cortex of rat kidney where initial damage from ischemia occurs. The tissue was diced in the cold, homogenized with a Dounce homogenizer, spun twice at 600 g, and the supernatant at 15,000 g for pelleting of mitochondria.
Some Contributions of Phosphatase and 3,3'-Diaminobenzidine Cytochemistry to Cell Biology
Authors: Novikoff Alex B.
Published: June 2020

This presentation will highlight cytochemical studies that have illuminated some aspects of structure and function of the endoplasmic reticulum (ER); these have been reviewed recently (1, 2). Phosphatase (Pase) cytochemistry has led to the formulation of new questions regarding secretory mechanisms in a number of endocrine and exocrine cells; it has also made the status of GERL as a distinct organelle considerably firmer. 3,31-diaminobenzidine (DAB) cytochemistry has revealed the presence of an organelle apparently ubiquitous in mammalian cells, the anucleoid peroxisomes(microperoxisomes). DAB cytochemistry has been utilized recently by Gonataset al. (3) to demonstrate that internalized plasma membrane is transported to GERL.

Our initial use of Pase cytochemistry to visualize cell organelles included nucleoside diphosphatase (NDPase), thiamine pyrophosphatase (TPPase), and acid Pase (AcPase). NDPase hydrolyzes the diphosphates of inosine, uridine, and guanosine but not cytidine or adenine diphosphates. Since the work of Yamasaku and Hayaishi (4) we have used TPPase and NDPase interchangeably.
PAP, A Secreted Androgen-Dependent Acid Phosphatase of Prostate
Authors: Serrano José A. , Paul Buddha D. , Wasserkrug Hannah L. , Serrano Anna A.
Published: June 2020

As previously reported (1,2), phosphorylcholine (PC) and D-ephedrine phosphate (DEP) are specific substrates for a non-lysosomal secreted acid phosphatase of prostate (PAP) as opposed to other acid phosphatases, e.g., lysosomal. The specificity of PC and DEP for PAP is due mainly to steric hindrance, a feature that renders these substrates resistant to hydrolysis by other acid phosphatases. This report deals with ultracytochemical results of applying this method to the studies of ventral prostate of castrated, hypophysectomized, testosterone treated (after castration) and normal rats. Male rats (Sprague Dawley) weighing approximately 200 g were used. Animals were sacrificed 4 or 7 days after castration and ventral lobes of the prostate were removed. Hypophysectomized rats were obtained commercially (Taconic Farms, Inc.) and were sacrificed 14 days after hypophysectomy. Rats were injected subcutaneously with 2 mg testosterone in sesame oil for 4 days.

Prostates of 4 normal, 4 castrated, 4 hypophysectomized and 4 castrated and testosterone treated rats were studied.
Acid Phosphatase Localization in the Cataractous Rat Lens
Authors: Unakar N.J. , Tsui J. , Reddan J.R.
Published: June 2020

Lysosomal enzymes seem to play an important role in wound healing and tissue repair (1,2, and 3). In the present investigation we have shown the existence of acid phosphatase and lysosomes in lenticular tissue and have examined the probable role of this enzyme in the induction of galactose cataract. Experiments were performed on Sprague-Dawley rats (50g) fed for 4 days on a diet consisting of equal proportions (by wt.) of Purina Rat Chow and D-galactose. Animals fed Purina Rat Chow alone served as controls. Acid phosphatase was localized by two separate procedures (4 and 5). Lenses were processed for electron microscopy as previously described (3). Lenticular tissue of both controls (Figs. 1 and 2) and galactose fed animals exhibits the reaction product of acid phosphatase. However, the group fed galactose showed a much stronger reaction product compared to controls.
Fluorescent and Immuno-Electron Microscopic Studies of la Antigen Distribution in Normal Human Skin
Authors: Rowden G. , Sullivan A.K. , Lewis M.G.
Published: June 2020

The I region of the H-2 histocompatability complex in mice is of interest because it plays a major role in numerous immune phenomena.

Ia (immune region assoc.) antigens are I region gene products which have been studied mainly in the murine system and have been shown to be present on the surface of B lymphocytes. These glycoproteins are also present in lesser quantities on T cells, macrophages, sperm and fetal liver cells.

Studies have been made of the distribution of la antigens in human skin, utilizing a heteroantiserum raised in rabbits. Cell membranes of a B lymphoblastoid cell line were solubilized with Triton X-100 in the presence of a protease inhibitor Trasylol. After clarification by ultracentrifugation the supernatant was passed over a Biogel A 1.5 column. The middle peak (160,000 Mol. Wt.) was then applied by a Con A-Sepharose affinity column.
Maytansine-Induced Mitotic Arrest in Human Lymphoblasts
Authors: Chao Tai-Te , Sullivan John , Krishan Awtar
Published: June 2020

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.

Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.
Observation of Human Low Density Lipoproteins in the Stem
Authors: Sogard M. , Deutsch D.
Published: June 2020

Blood serum low density lipoproteins (LDL), as well as playing a fundamental role in lipid transport, have been implicated in the development of arterial plaques in the disease atherosclerosis. Accordingly, their structure and especially their surface morphology is of great interest. Small angle x-ray scattering studies1 suggest the particle to be approximately spherical with convoluted surfaces. The outer layers of the particle are believed to consist of proteins and the polar groups of phospholipids and free cholesterol, while the core consists of neutral lipids. Previous electron microscopy has shown the particle to be approximately spherical with some surface structure visible in negatively stained specimens. However, the nature of the surface detail seen has varied, ranging from granularity2 to distinct, regularly ordered subunits3. We have recently examined this protein in negative stain with the 3 Å user's STEM in the laboratory of A.V. Crewe.
Ultrastructural Analysis of the Disruption of Ferritin by Acetone
Authors: Massover William H.
Published: June 2020

Ferritin is the major iron-storage protein in mammals (1, 2). The basic architecture of this large macromolecular complex originally was established in the 1954 electron microscope study by Farrant (3). Each ferritin molecule is a hollow sphere formed by the polymerization of 24 protein subunits; the ferric iron is sequestered within the central cavity as one or more crystallites of a unique mineral (1-4). The protein shell resists depolymerization by many harsh chemical treatments; this stability suggests that the subunit- subunit interactions are very strong. A partial disruption of some protein shells has been produced by certain physical treatments, such as freezing and thawing, boiling and cooling, and, drying and rehydrating (5).

Acetone has been used to precipitate ferritin from its aqueous solution (6). Dilution of acetone-precipitated ferritin with distilled water appears to result in complete resolubilization. The present study has examined the ultrastructure of horse spleen ferritin (Calbiochem) after this seemingly innocuous treatment.
Localization of Silver in the Spleen of Argyric Rats by Energy Dispersive X-Ray Analysis Coupled with Scanning and Transmission Electron Microscopy
Authors: Pereira G.
Published: June 2020

Previous electron microscopic observations of the spleen have revealed the white pulp to be completely separated from the extravasated blood in the surrounding marginal zone by a strategically-located, double layer of reticular cells ensheathing a coarse reticular fiber. Similarly, a single reticular cell layer has been observed to form a continuous investment for all white pulp capillaries. To test the significance of this apparent isolation of the splenic white pulp from the blood, the distribution and composition of silver deposits in the spleen of argyric rats were determined by transmission and scanning electron microscopy coupled with computer-assisted x-ray analysis.

Young male albino rats were made argyric by supplying them for many months with drinking water to which 1.5gm per liter of silver nitrate had been added. Specimens from the spleens of control and argyric animals were prepared for conventional transmission electron microscopy by glutaraldehyde-osmium fixation. For scanning electron microscopy, other specimens were fixed in buffered glutaraldehyde, freeze-dried in vacuo, coated with a thin film of gold- palladium and examined in a Cambridge Stereoscan Mark II.
Galactoflavin Induced Riboflavin Deficiency: Effects on Rat Sciatic Nerve, Liver, and Novikoff Hepatoma Cells
Authors: Norton William N. , Savage Howard , Lane Montague , Thurston E. Laurence
Published: June 2020

Information concerning cell structure and function during riboflavin deficiency is important in view of the finding that treatment of human neoplasms such as lymphosarcoma and Hodgkin's disease with a riboflavin deficient regime and galactoflavin, a riboflavin antagonist, induces partial remission (1).

Results from the present study indicate that riboflavin deficiency severely affects the structural integrity of myelin lamellae (Fig. 1). The myelin sheath undergoes a form of dissociation or separation, in essence a pulling apart of adjacent membranes. In addition, there are marked degrees of fragmentation not only of the myelin membranes but also of the axolemma. These results correlate well with clinical data which reveal that various sensory and motor pathways are adversely affected by a riboflavin-deficient diet (2). The riboflavin deficiency produces no discernible effects upon organelle content of neurons. Organization and integrity of microtubules, neurofilaments and mitochondria are maintained at least until fragmentation of the axolemma occurs. Nonmyelinated nerve fibers do not appear to be affected ultrastructurally by the deficiency.
Ultrastructure and Analysis of Striae
Authors: Kischer C.W. , Arem A.J.
Published: June 2020

Cutaneous striae are believed to occur in glucocorticoid-stimulated skin and have been morphologically identified with a rupture of thick elastic fibers and a straightening of collagen bundles.

The fact that striae are usually flattened or depressed areas would tend to suggest they are not true closed dermal wounds and would be metaboli- cally inactive. To examine this possibility we have analyzed striae by light and electron microscopy and by preliminary biochemical assays. Striae were removed from a skin wedge taken from a 45 year old woman undergoing an abdominal lipectomy. The age of the striae was probably several years. The tissues to be studied morphologically were fixed in Karnovsky's fluid while those reserved for biochemical assay were either used fresh or frozen.

The striae portion was excised from adjacent clinically-normal skin and data from each area was compared.

No apparent reduction of elastic tissue occurs throughout the breadth or depth of the stria area.
The Effect of Some Alkaloids on the Ultrastructure of Phenolic-Containing Cells in the Endodermis of Cotton Roots
Authors: Mueller Walter C. , Rodehorst Ellen
Published: June 2020

The study of the ultrastructure of phenolic-containing cells is difficult because after fixation in glutaraldehyde and osmium these cells have a dense, osmiophilic appearance in which cytoplasmic detail is obscured. Usually this effect is most marked in mature cells, e. g. cells at a stage of differentiation in which the central vacuole occupies a major portion of the cell volume. In such cells the tonoplast is apparently very susceptible to injury, for during the fixation process the phenolics leach from the vacuoles into the cytoplasm where they subsequently combine with the osmium. Leaching of the phenolics and the resultant darkening of the cytoplasm can be inhibited by a primary fixation in low concentrations of glutaraldehyde (1, 2). We have sought to corroborate this effect by using various alkaloids in the fixation process.
Procedure for Contrasting Glycogen in the Embryonic Chick's Inner Ear
Authors: Siegel A. J. , Fermin C. D.
Published: June 2020

In many cells, glycogen particles are often difficult to identify because of their resemblance to ribosomes and their obscurity in dense or granular cytoplasm. In the present study, we examined the embryonic chick's lagena, the auditory portion of the avian ear, in order to compare the appearance of glycogen in normally fixed and treated tissue (1). In the latter, glycogen particles were readily localized even in seemingly recalcitrant embryonic tissue because the procedure selectively contrasts glycogen particles but not ribosomes. Subsequent staining, however, restores some of the electron density to ribosomal particles. According to Bruijn's procedure, the tissue is prefixed in glutaraldehyde for 72 hrs, then post-fixed for 24 hrs in a solution containing 1% 0s04 and 0.05 M K3Fe(CN)6. We found that the procedure's primary disadvantage is the moderate loss of cytoplasmic integrity that accompanies the extended exposure to the postfixation-reaction medium, giving cells a dull, moth-eaten appearance (Figs. 2 and 4).
Single Processing of Tissue for Light and Electron Microscopy
Authors: Burns W. A. , Bretschneider A. M. , Morrison A. B.
Published: June 2020

Tissues for light and electron microscopy are traditionally processed separately. Different fixatives and embedding media are usually employed. Paraffin is unsuitable for electron microscopy and the small amounts of tissue generally embedded in plastic makes sampling a significant problem for the light, as well as the electron microscopist. Techniques, however, have been described for plastic embedding of large samples of tissue which can be sectioned at 1 μm. The added resolution of these thinner sections potentially increases the diagnostic ability of the light microscopist. These techniques have not been fully utilized in pathology. If one fixative were utilized and the quantity embedded in plastic were comparable to that which is normally processed for paraffin, then the investigator could use plastic sections for better light microscopic evaluation with the option of subsequent examination of the same region in the same block at an ultrastructural level.
SEM of Hepatocytes and Biliary Passages in Goldfish Liver
Authors: Nopanitaya Waykin , Grisham Joe W. , Carson Johnny L.
Published: June 2020

An interesting feature of the goldfish liver is the morphology of the hepatic plate, which is always formed by a two-cell layer of hepatocytes. Hepatic plates of the goldfish liver contain an infrequently seen second type of cell, in the centers of plates between two hepatocytes. A TEH study by Yamamoto (1) demonstrated ultrastructural differences between hepatocytes and centrally located cells in hepatic plates; the latter were classified as ductule cells of the biliary system. None of the previous studies clearly showed a three-dimensional organization of the two cell types described. In the present investigation we utilize SEM to elucidate the arrangement of hepatocytes and bile ductular cells in intralobular plates of goldfish liver.

Livers from young goldfish (Carassius auratus), about 6-10 cm, fed commercial fish food were used for this study. Hepatic samples were fixed in 4% buffered paraformaldehyde, cut into pieces, fractured, osmicated, CPD, mounted Au-Pd coated, and viewed by SEM at 17-20 kV. Our observations were confined to the ultrastructure of biliary passages within intralobular plates, ductule cells, and hepatocytes.
The Genesis of Cardiac Myofibrillar Disarray by Alterations in Stress Vectors
Authors: Adomian Gerald E. , Beazell James W. , Furmanski Martin
Published: June 2020

Several investigators have reported bizarre, disarrayed myofibrils in hearts in cases of ventricular hypertrophy. This disarray is characterized by myofibrillar branching and divergence of the orientation of sarcomeres. (Fig.1) The resulting picture is one in which individual sarcomeres within the same cell may lie at angles of up to 90°, rather than parallel to each other. These bizarre, disarrayed myofibrils are found commonly in the area of the interventricular septum in cases of hypertrophic cardiomyopathy, in areas surrounding old myocardial infarcts, and in areas of unusual contraction geometry. In the course of examining myocardial tissues from dogs in heart block, we have made observations which lead us to the development of an hypothesis concerning the genesis of myofibrillar disarray. These observations seem to indicate that areas of disarray are related to abnormalities in the geometry of contraction within the myocardium.
Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain
Authors: Peachey Lee D. , Franzini-Armstrong Clara
Published: June 2020

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.
Contraction Bands in Human Hearts: Pathology or Artifact?
Authors: Adomian G.E. , Laks M.M. , Billingham M.E.
Published: June 2020

With increasing use of myocardial biopsy as a diagnostic tool, different criteria of pathology have evolved from tissues obtained from biopsy and post mortem specimens. Since contraction bands have been present in myocardial tissue associated with various cardiac pathological states, their presence have been interpreted as being a part of these pathological processes. For example, CB have been used as a morphological index of pathology in conditions such as ischemia, cardiomyopathy, and catecholamine toxicity. We recently reported that contraction bands may be produced artifactually by the biopsy procedure in the fresh, but not the post mortem or perfused fixed normal rat heart (1). In order to establish the generality of these results we undertook the present study,the aim of which was to determine the incidence and significance of CB in biopsies from the normal human heart.

Biopsy specimens were obtained from twelve normal young individuals who had recent irreversible traumatic damage to their brain.
SEM Cold Stage Techniques for the Observation of Vegetative and Floral Apices of Oat (Avena sativa L.) Plants
Authors: Kirchoff B. K. , Allard L.F. , Bigelow W.C.
Published: June 2020

In attempting to use the SEM to investigate the transition from the vegetative to the floral state in oat (Avena sativa L.) it was discovered that the procedures of fixation and critical point drying (CPD), and fresh tissue examination of the specimens gave unsatisfactory results. In most cases, by using these techniques, cells of the tissue were collapsed or otherwise visibly distorted. Figure 1 shows the results of fixation with 4.5% formaldehyde-gluteraldehyde followed by CPD. Almost all cellular detail has been obscured by the resulting shrinkage distortions. The larger cracks seen on the left of the picture may be due to dissection damage, rather than CPD. The results of observation of fresh tissue are seen in Fig. 2. Although there is a substantial improvement over CPD, some cell collapse still occurs.

Due to these difficulties, it was decided to experiment with cold stage techniques. The specimens to be observed were dissected out and attached to the sample stub using a carbon based conductive paint in acetone.
SEM Study of Insect Tissue Using Ethanol-Infiltrated Cryofracture Followed by Critical Point Drying
Authors: Sanford Malcolm T. , Dietz Alfred
Published: June 2020

Transmission electron microscopy has been used for most ultrastructural study of insect tissue. This is particularly true for investigations of glands associated with the insect epidermis and cuticle (1). The advent of ethanol-infiltrated cryofracture of biological tissue followed by critical point drying, however, enables closer examination of surface topography and three dimensional conformation of glands and other structures associated with the insect cuticle by scanning electron microscopy (2).

In the queen honey bee (Apis mellifera L.), a wide band of gland cells is located beneath tergites three, four and five of the abdomen, called subepidermal glands (3). Epidermal cells and modified epidermal cells, tormogen cells, are also found beneath the cuticle near the subepidermal glands (4).

Scanning electron microscopy of ethanol-infiltrated fractured tergites of the queen honey bee which have been critical point dried revealed that the subepidermal gland cells were spherical in shape (Fig. 1).
Ultrastructural Characterization of 18-24 Hr. Neurospora Crassa Hyphae by Freeze-Fracture Techniques
Authors: Howard K. S. , Socolofsky M. D. , Braymer H. D. , Clisham P. R.
Published: June 2020

The ultrastructure of Neurospora crassa hyphae has been characterized primarily by the thin section technique. Since the original work of Shatkin and Tatum1, however, the quality of thin sections has been hindered by difficulty in fixing, embedding, and staining. A recent study of N. crassa ascospores compared the ultrastructure as revealed by freeze-etch to that revealed by thin sections, demonstrating the utility of the freeze-etch method when applied to organisms that have been difficult to prepare for EM observation2. The present study applies freeze-fracture to II. crassa in an attempt to confirm and increase the ultrastructural information presently available.

Neurospora crassa strains 73a and 74A were grown in Vogel's minimal citrate medium for 18 to 24 hours. The resultant hyphae were treated with 3% glutaraldehyde in 0.1 M phosphate buffer for 2 hours followed by immersion in 30% glycerol for 1 hour or transferred directly to 30% glycerol from growth medium without glutaraldehyde fixation.
Development of the Acrosome During Spermiogenesis in Arion Hortensis Ferussac (Stylommatophora, Pulmonata)
Authors: Maxwell W. L.
Published: June 2020

It has been suggested that in internally fertilising animals the acrosome is of reduced importance where species recognition occurs at the individual rather than cellular level (1).

However, a complex acrosome is present in the spermatozoon of Arion hortensis. and a specialised accessory structure is formed during acrosomal development.

The proacrosomal granule is deposited at the presumptive nuclear apex early in spermiogenesis by the Golgi apparatus - but subsequent development occurs without any Golgi association. The granule is initially oblong when viewed in longitudinal section being 400nm long. There is no visible substructure as shown in Fig.l. During spermiogenesis the acrosome parallels the elongation of the nucleus. At about mid-spermio- genesis the columnar proacrosome is 600nm long and Fig.2 shows some internal differentiation. A central rod of material is visible with a basal concavity which is closely associated with the anterior tip of the maturing nucleus.
Cerebral Tissue Response in Chronic Electrode Implantation
Authors: Dodson R.F. , Chu L.W-F , Ishihara N.
Published: June 2020

The extent of damage surrounding an implanted electrode in the cerebral cortex is a question of significant importance with regard to attaining consistency and validity of physiological recordings. In order to determine the extent of such tissue changes, 150 micron diameter platinum electrodes were implanted in the cortex of four adult baboons, and after eight days the animals were sacrificed by whole body perfusion with a 3% glutaraldehyde in 0.1M phosphate fixative.

The calvarium was carefully removed and the electrode tracts were readily discernible in the firm, glutaraldehyde fixed tissue.

Careful dissection of the zone of the electrode tract resulted in a small block which was further sectioned into tip, mid-tract and surface areas. Ultrastructurally, damage extended from the electrode sheath to the greatest extent of from 0.2 to 3.5 mm.
TEM and SEM on Glycerol-Induced Communicating Hydrocephalus in Suckling Rats
Authors: Chou S.M. , Origuchi Y.
Published: June 2020

In a previous study, we could persistently induce a communicating hydrocephalus in suckling rats by an intracerebral inoculation of minute amounts of 3 different antitubulin compounds (1). Contrary to our expectation, the microtubules in the cilia and the basal bodies were not altered. Since the intramembranous molecular changes may be induced with an antitublin solution of far less concentration than that induces antitublin effects (2), the induced hydrocephalus was thought to be secondary to membranous alterations and subsequent cessation of ciliary movement. The present investigation was undertaken to test if a nontoxic compound such as glycerol, which is not antitublin but may alter the intramembranous structures and active transport system of membranes (3) may induce the similar communicating hydrocephalus. To 80 suckling rats (4 to 10 days old), 0.02 to 0.04 ml of glycerol (B & A, Allied Chemical Co., N.J.) in a single dose was intracerebrally injected, and to 40 control rats of comparable ages, 0.02 ml of saline in the same manner.
Ultrastructural Morphology of the Anagen Stage Hair Follicle of Male Beagle Dogs
Authors: Al-Bagdadi F. A. , Titkemeyer C. W. , Lovell J. E.
Published: June 2020

Skin biopsy samples were collected monthly from the lateral sides of 9 male Beagle dogs over a period of 1 year. The samples were fixed in 3% gluteral- dehyde and post fixed in 1% osmium tetroxide using phosphate or S-Collidine as buffers. They were dehydrated, embedded in Epon 812, sectioned with an LKB Ultrotome III, and stained with Reynolds' lead citrate and 1% uranyl acetate. They were examined and photographed by use of an RCA-3H electron microscope.

The dermal papilla during anagen consisted of fibroblast-like cells some of which had cytoplasmic processes. The cytoplasm contained many mitochondria. (Fig. 1) The cells of the dermal papilla were either peripherally arranged spindle-shaped cells or polygonal cells. The basement membrane was either related to the fibroblast cytoplasmic processes or was free of the cytoplasmic processes but with a thick zone composed of fibers, granular ground substance and spaces.
The Effects of Phenyl Mercuric Acetate (PMA) on the Ultrastructure of the Paint Mildew, Aureobasidium Pullulans
Authors: Crang Richard E. , Pechak David G.
Published: June 2020

For over 30 years Aureobasidium pullulans (DeBary) Arnaud has been considered the primary fungal agent involved in mildew-induced defacement of painted surfaces (1). Although mercury compounds have been incorporated into the paints as mildewcides, little is known relative to the action of mercury on fungal cells (2). The purpose of this study is to determine the ultrastructural effects of a commonly used mildewcide, phenyl mercuric acetate (PMA), on A. pullulans.

All experimental cultures of A. pullulans were grown on a defined medium containing: (NH4)2S04, 3.0 g; K2HP04, 1.0 g; MgSO4.7H20, 0.5 g; KC1, 0.5 g; FeSO47H2O, 0.1 g; sucrose, 10.0 g per liter dist. H2O. The medium was solidified with 2 per cent agar. Two sets of media were inoculated with a blastospore suspension of A. pullulans. One set contained only the above defined medium, while the second set contained 200 ppb (5xlO-7M) PMA supplementing the defined medium.
Ultrastructural Changes of Gerbil Epididymis after Vasectomy
Authors: Majumdar Shyamal K. , Shapiro Marion , Caputi J. Gary
Published: June 2020

Ultrastructural studies of gerbil testes after vasectomy have been described (2S3). The present study was undertaken to obtain additional information on the effects of vasectomy in the fine structures of the epididymis of the Mongolian gerbils(Meriones unguiculatus). The animals were subjected to vasectomy or sham operation at intervals up to one year. An incision was made on the ventral side of the animal just above the scrotum, and about one centimeter of each vas deferens was removed and the ends were firmly ligated. The cauda epididymis of vasectomized and sham operated animals was fixed for two hours in Karnovsky's fixative. Following a rinse in buffer, the tissue was post fixed for one hour in osmium tetroxide, dehydrated, and embedded in Epon 812. The sections were stained with uranyl acetate followed by Reynolds' lead citrate, and examined with a Philips 201 transmission electron microscope operating at 60 kV.
Quantification of losses during X-ray microanalysis of mercury
Authors: Bistricki T.
Published: June 2020

Diminution of the X-ray signal from the elements of low atomic number and mass loss associated with electron excited X-ray microanalysis have been demonstrated elsewhere. The elements of higher atomic number did not receive sufficient attention although under severe conditions of analytical electron microscopy, the losses of any of the specimen's elemental components exposed to the electron beam bombardment in high vacuum are to be expected and have been indicated previously. Unlike the elements of low atomic number, the losses of heavier elements, like mercury, are usually not detected unless a mass of the element within the excited volume is at a very low level (10-11 g range or less) or analytical conditions are extremely unfavourable, in which case considerable losses may occur even when concentration levels are by orders of magnitude higher (10-9 g range or higher).