bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced Resolution of Dislocation Imaging at High Voltages
Authors: Osiecki R. , Thomas G. 
Published: June 2020

Some results of up to 12 beam contrast calculations for systematic orientations have indicated that high order reflections at high voltages may provide improved dislocation resolution. For example the contrast profiles for dislocations show a decrease in image width for increasing order of reflection (i.e. increasing ḡ·), thus enabling improved resolution of narrow dislocation dissociations and closely spaced dipoles or superdislocations.This paper provides experimental confirmation that high order systematic reflections do indeed result in an improvement in bright field image resolution, e.g. image widths of dislocations can be reduced by a factor of ~3. The results have been obtained from [001] foils of GaAs semiconducting devices in which dislocations are associated with surface and interfacial defects. In each case the crystal is set at the exact Bragg condition for each reflection along the systematic row being used. The work was done on the Berkeley Hitachi microscope operated at 650 kV.
Electron Microscopy of Thin Film Immiscible-Miscible Systems
Authors: Staudhammer K. P. , Murr L. E. 
Published: June 2020

Some preliminary studies on immiscible systems have been previously reported. This paper is a continuation of this work in an effort to expand the characterization of immiscible systems. The non-equilibrium behavior of many thin film materials compared to that of the bulk is fairly well established. The work discussed in the present paper is a comparative investigation of immiscible systems such as Ni-Ag to that of a simple eutectic, Ag-Si. Earlier work on immiscible systems has shown that upon thermal activation, one of the components exsolves out of the matrix and grows as single crystals upon the thin film matrix. Further investigation revealed this to be characteristic of a number of immiscible systems; however, a few anomalies have been found.Thin films were prepared by the co-evaporation of the components from separate sources at ambient temperatures onto freshly-cleaved (100) NaCl substrates. The co-evaporated films (300-400 Å thick) were deposited at a nominal background pressure (prior to deposition) of 4 X 10-5torr.
Aspirin-Induced Damage to the Gastric Mucosa
Authors: Pfeiffer C. J. , Weibel J. , Bair J. W. , Roth J. L. A. 
Published: June 2020

The gastric bleeding diathesis related to ingestion of salicylate compounds has long been recognized. Although the pathogenesis of this common adverse drug reaction is poorly understood, hypotheses have been advanced suggesting the direct irritation of the mucosa by salicylate, impaired mucus protection of the gut surface, back diffusion of hydrogen ions, and adverse systemic effects of salicylate on the mucosal metabolism. The present study was undertaken to characterize the early cytologic responses, the relative sensitivities of different mucosal cell types, and the mucosal surface damage related to bleeding after oral ingestion of aspirin.Acetylsalicylic acid (10 mg/kg) in an acidic solution (0.1 N HCl) was administered by gastric intubation to normal adult female ferrets, and animals were sacrificed at 10-45 min after ingestion. Control ferrets received 0.9% NaCl, 0.1 N HC1, or a solution containing both aspirin and sodium bicarbonate buffer (10 mEq/kg). Tissue samples taken from both the antrum and fundus of the stomach, were prepared in a conventional manner and studied with a Jeolco Jem-7 Transmission Electron Microscope.
A New Cell-Type in the Impulse-Conducting Tissue of Rat Heart
Authors: Sekhri K. K. 
Published: June 2020

The ultrastructural alterations induced in the contractile cardiac tissue of rats by chronic administration of alcohol have been reported previously. The present paper deals with the cardiotoxic effects of ethanol on the impulse-conducting tissue. Several groups of male simonsen rats were fed commercial Purina rat chow diet and 15% ethanol ad libitum for 55 weeks. The controls were maintained on chow diet and distilled water. For electron microscopy tissue samples from atrium were fixed in 2.5% Cacodylate-buffered Glutaraldehyde, post-fixed in 2% buffered Osmium tetroxide and embedded in Epon-Araldite.On EM examination, the myocardial cells of alcoholic rat showed profound ultrastrcutural changes involving the formation of giant mitochondria by a process of coalescence, coupled with the fragmentation of myofibrils and the dehiscence of the intercalated discs. The conduction tissue of the treated animals, however, revealed an unusual type of cell, which to my knowledge has not been reported before in the literature. This peculiar conduction cell was wedged in between the ordinary myocardial cells and was characterized by a few remnants of sarcomeres delimited by dark Z lines and the familiar thick and thin filaments. The glycogen granules were scanty and the few mitochondria were randomly scattered.
Adenomatoid Tumor of the Testis, A Mesonephric Hamartoma
Authors: Fresco Raoul , Chang-Lo Mary 
Published: June 2020

Confusion surrounds the nature of the “adenomatoid tumor” of the testis, as evidenced by the large number of synonyms which have been ascribed to it. Various authors have considered the tumor to be of endothelial, mesothelial or epithelial origin. There appears to be no controversy as to the stromal elements of the tumor, which consists mainly of smooth muscle and fibrous tissue. It is the irregular gland-like spaces which have given rise to the numerous theories as to its histogenesis, and even recent ultrastructural studies fail to agree on the origin of these structures.Electron microscopy of a typical intrascrotal adenomatoid tumor showed the gland-like spaces to be lined by epithelial cells (Fig. 1), rich in cytoplasmic tonofibrils and united to each other by numerous desmosomes (Fig. 2). The most salient feature of these epithelial cells was the presence on their luminal surface of numerous long and repeatedly branching microvillous structures of the type known as stereocilia (Fig. 3). These are extremely long slender cell processes which are as much as three to four times the length of those in brush borders.
Ultrastructural Changes in the Epidermal Cells of the Cotyledon in the Germinating Seeds of Euphorbia esula
Authors: Fellows R. J. , Hayat M. A. 
Published: June 2020

The transformation of an apparently inanimate seed into a viable, growing organism has been the object of many investigations. Several investigators have studied the ultrastructure of the seed embryo both in the dormant and in the germinating seed (e.g., Yoo, 1970). While mature leaves of the family Euphorbiaceae have been studied (Marty, 1969), no work has been reported on the embryo of the germinating seed. The objective of this study was to follow the ultrastructural changes in the epidermal cells of the cotyledon accompanying the germination of the seed.Samples were taken from the cotyledons of both the dormant and the germinating seeds. The seeds were germinated on moistened filter paper in the dark at 20-22°C. Samples of germinating seeds were taken at 3,4,5,6,7 and 8 days after initial imbibition. All tissue samples were processed according to standard procedures (Hayat, 1970).
A SEM and Light Microscope Study of the Epidermal Leaf Structures of the Carnivorous Plant, Sarracenia purpurea, L.
Authors: Panessa B. J. , Gennaro J. F. 
Published: June 2020

Tissue from the hood and sarcophagus regions were fixed in 6% glutaraldehyde in 1 M.cacodylate buffer and washed in buffer. Tissue for SEM was partially dried, attached to aluminium targets with silver conducting paint, carbon-gold coated(100-500Å), and examined in a Kent Cambridge Stereoscan S4. Tissue for the light microscope was post fixed in 1% aqueous OsO4, dehydrated in acetone (4°C), embedded in Epon 812 and sectioned at ½u on a Sorvall MT 2 ultramicrotome. Cross and longitudinal sections were cut and stained with PAS, 0.5% toluidine blue and 1% azure II-methylene blue. Measurements were made from both SEM and Light micrographs.The tissue had two structurally distinct surfaces, an outer surface with small (225-500 µ) pubescent hairs (12/mm2), numerous stoma (77/mm2), and nectar glands(8/mm2); and an inner surface with large (784-1000 µ)stiff hairs(4/mm2), fewer stoma (46/mm2) and larger, more complex glands(16/mm2), presumably of a digestive nature.
Freeze-Etching of Intranuclear Adenovirus
Authors: Brown Dennis T. , Burlingham Byron T. 
Published: June 2020

Adenoviruses are revealed by negative staining to be icosahedral in structure and composed of 252 subunits (insert Fig. 1). The vertices have a fiber-like projection which has been implicated in the adsorbtion of the virus to the host cell. Ultra thin sections of adenovirus-infected cells has revealed that virus morphogenesis occurs in the nucleus.Human carcinoma (KB) tissue culture cells were productively infected with adenovirus type 2 at a multiplicity of 10 and incubated for 40 hours at 37°C. The infected monolayers were fixed in place with 1%, gluteraldehyde buffered in Millonigs phosphate buffer. The fixed cells were suspended in 30%, glycerol and processed according to the procedure of Moor in a Balzers 360 M freeze etch unit with an etching time of 70 seconds at -100°C. A second portion of the fixed cells in glycerol was post-fixed with 1% osmium tetroxide and embeded in epon 812 for ultrathin sectioning.
Structure and Function of Isolated Mucosal Cells of the Urinary Bladder of Turtle (Pseudemys scripta)
Authors: Yoder M. J. , Gennaro J. F. , Linsky N. B. , Brodsky W. A. , Scott W. N. 
Published: June 2020

The isolated urinary bladder of the fresh water turtle (Pseudemys scripta) actively transports sodium, chloride and bicarbonate from the luminal to the blood side of the tissue. Electron micrographs of the intact epithelium reveal several cell types. We have attempted to separate the various cell types in order to determine whether structural heterogeneity is paralled by functional heterogeneity.Urinary bladders, were dissected from exsanguinated turtles, and rinsed with Ringer's solution. The necks of thess bladders, in the form of closed sacs, were each tied to the outlet of a Luer lock syringe, filled with and immersed in Ca++ free Ringer's solution containing 2 mM EDTA, and incubated for 60 min. at 25°C. The fluid containing the disaggregated mucosal cells was collected and centrifuged at 5,000 g for 15 min. (2X). The cells were resuspended in Ringer's solution (containing 2 mM EDTA)and layered over a Plcoll gradient. Ficoll dissolved in EDTA-Ringer's was used to prepare discontinuous gradients (5-30 % Ficoll) in a Beckman SW-27 rotor.
Qualitative and Quantitative Analysis of tRNA with the Electron Microscope
Authors: Yoshikami Doju , Abermann Reinhard J. 
Published: June 2020

Several investigators have already performed EM studies of tRNA; however, they did not report any statistical assessment of their EM micrographs, and it appears that their preparative procedures may have been limiting in this regard. In contrast, the reproducibly uniform distributions of tRNA particles in the EM micrographs obtained by the procedures described in the accompanying paper allow us to readily identify and characterize tRNA by EM in a quantitative manner. In order to exploit this ability, we have conducted experiments wherein monomers and dimers of tRNA were examined.We have synthesized covalently bonded dimers of tRNA where the monomeric units were linked to each otherviatheir 3′ termini. The 3′ terminal ribose moieties of two monomers were cross-linked with a dihydrazide to produce the dimer. The dimer was purified after synthesis by gel-filtration chromatography (Fig. 1). The preparatory procedure for EM visualization described in the accompanying paper gave sufficient resolution so that the dimer could be readily distinguished from the monomeric starting material (compare Fig. 2a (dimer) with Fig. 2c (monomer)).
Structures Formed by Cryoprotective Agents Used in Freezc-Etching
Authors: Cocks G. G. , Cluthe C. E. 
Published: June 2020

The freeze etching technique is potentially useful for examining dilute solutions or suspensions of macromolecular materials. Quick freezing of aqueous solutions in Freon or propane at or near liquid nitrogen temperature produces relatively large ice crystals and these crystals may damage the structures to be examined. Cryoprotective agents may reduce damage to the specimem, hut their use often results in the formation of a different set of specimem artifacts.In a study of the structure of polyethylene oxide gels glycerol and sucrose were used as cryoprotective agents. The experiments reported here show some of the structures which can appear when these cryoprotective agents are used.Figure 1 shows a fractured surface of a frozen 25% aqueous solution of sucrose. The branches of dendritic ice crystals surrounded hy ice-sucrose eutectic can be seen. When this fractured surface is etched the ice in the dendrites sublimes giving the type of structure shown in Figure 2. The ice-sucrose eutectic etches much more slowly. It is the smooth continuous structural constituent surrounding the branches of the dendrites.
A Simple, Reliable Method for Preparing Perforated Formvar Films
Authors: Eisner Paul R. 
Published: June 2020

Perforated films used as test specimens for compensation of asymmetry in electron microscope lenses can be made by introducing water or glycerol into a Formvar solution. This can be done by preparing an emulsion or by exposing a thin layer of Formvar solution on the surface of glass to steam or moist air. Consistent production of small, round test holes with smooth edges is difficult. The following method employs solvent treatment for enlarging perforations formed in high humidity. Edge characteristics and hole size can be controlled easily and consistently. Useful holes as small as 0.15μ diameter can be produced.Procedures described by Bradley are used to clean glass slides, dissolve Formvar in ethylene dichloride, cast films on glass, and mount films on grids. In a room or chamber at room temperature (23 C) with 50-70%. relative humidity, the clean glass slides are dipped into a Coplin staining jar containing 0.2-0.4% (w/v) Formvar solution. Figure 1 shows perforations formed during casting in a chamber at 60% relative humidity using a 0.4% Formvar solution. The perforated films are mounted on grids, which are immersed in acetone, absolute methanol, or chloroform-absolute methanol (1:9) contained in compartments of a depression plate.
Fibrin Clots for Electron Microscopy and Cytochemistry of Minute Biological Samples
Authors: Sicko Linda M. , Arnold Wm. James 
Published: June 2020

The inclusion of loose cells and tissue fragments in protein or agar matrices is an accepted method to facilitate handling and processing for microscopy. Means of attaining the matrix have extended from the use of chicken blood plasma to highly refined and expensive nucleohistone gels, but more often, the difficult and often unsatisfactory suspension of materials in molten agar. Fibrin clots, introduced by Chatton and Lwoff, have the advantages of availability, speed and ease of application, predictability, homogeneity of dispersal, low expense, and applicability to the embedding of a wide variety of specimens in polymers for light and electron microscopy. The fibrin clot is high among the preferred methods of manipulating fragile protistes and yeasts and mycetozoans and fungi.Fibrin is compatible with most common buffer systems except ones containing cacodylate, as noted by Charret and Fauré-Fremiet. By manipulating fibrinogen content, clots may be prepared with densities ranging from an open, mucus-like network, just binding specimen particles together (200 mg per 100 ml), to hard agar-like gels capable of withstanding considerable rough handling (1.5 percent). With animal cell suspensions and blue-green algae we prefer a concentration of 0.7 percent bovine fibrinogen, Cohn fraction I (Nutritional Biochemicals, Cleveland) dissolved in distilled water with the salts suggested by Furtado: sodium citrate, 0.16 percent and sodium chloride, 0.85 percent. Bovine fibrinogen is least expensive but the amount of clotable material varies according to the manufacturer, thus norms may have to be adjusted when changing lots. We prefer to use freshly prepared solutions of fibrinogen. Thrombin (Parke-Davis, Detroit) is used in sterile distilled water or saline at a concentration of 100 N.I.H. units per milliliter. Thrombin may be stored frozen at least 2 months in 10x concentrated stock solution.
Selective Staining of Pulmonary Type II Alveolar Cell Lamellar Bodies in “I-Micron” Plastic Sections
Authors: Mackay G. R. 
Published: June 2020

Schlipköter in 1954 described a concentric lamellated osmiophilic body contained within the cytoplasm of certain pulmonary alveolar epithelial cells. The occurrence of these bodies and microvilli on the free cell border is the ultrastructural trademark of the type II alveolar epithelial cell. Numerous reports have been made concerning the histogenesis of this cell type and the composition and function of its lamellated inclusions. Though the significance of these bodies remains undetermined, their faithful occurrence facilitates the identification of the type II cell in fine structure studies.In paraffin sections of lung tissue, vacuoles are found in those cytoplasmic areas of the type II cell which are normally occupied by the lamellar inclusions. Presumably a chemical extraction has occurred during the embedding procedure. Thus, the identification of the type II cell in these sections is based mainly upon its shape and location. When 1-2 micron-thick sections of plastic-embedded lung tissue are stained with methylene blue and azure II, then counterstained with basic fuchsin according to the method of Mackay and Mead, the lamellar bodies of the type II cell show an affinity for the basic fuchsin.
Ultrastructure of Oviduct Epithelium of the Porcine in Estrus
Authors: Nayak R. K. , Zimmerman D. R. 
Published: June 2020

Cyclic changes of porcine oviduct epithelium studied by light microscopy were first reported by Snyder in 1923. UltrastructuraI features of the porcine oviduct epithelium have not yet been described. Electron microscopic studies of oviduct epithelium have been reported for only a few species. These reports have been recently reviewed by Nilsson and Relnius. This report describes the fine structure of, the oviduct epithelium and attempts to elucidate the mechanism of ciliogenesis and the secretory process in the porcine during estrus.Tissue sections from the fimbria and ampulla were fixed in cold 3% cacodylate buffered glutaraldehyde (pH 7.4), post-fixed in 1% osmic acid and embedded in Epon. Ultra-thin sections were stained with uranyl acetate and lead citrate and examined in a RCA 3-G electron microscope operated at 100 kv.The epithelium of the tubal mucosa consists of secretory and ciliated cells. The cells are columnar and rest on a common basement membrane, which is about 50 mμ thick. The distal or free borders of the surface epithelial cells possess few irregular microvilli. The membranes of adjacent cells show tight intercellular junctions and macula adhaerentes (Figs. 1, 2).
Early Development of Drug-Induced Hepatic Necrosis
Authors: Zaki F. G. , Detzi E. , Keysser C. H. 
Published: June 2020

This study represents the first in a series of investigations carried out to elucidate the mechanism(s) of early hepatocellular damage induced by drugs and other related compounds. During screening tests of CNS-active compounds in rats, it has been found that daily oral administration of one of these compounds at a dose level of 40 mg. per kg. of body weight induced diffuse massive hepatic necrosis within 7 weeks in Charles River Sprague Dawley rats of both sexes. Partial hepatectomy enhanced the development of this peculiar type of necrosis (3 weeks instead of 7) while treatment with phenobarbital prior to the administration of the drug delayed the appearance of necrosis but did not reduce its severity.Electron microscopic studies revealed that early development of this liver injury (2 days after the administration of the drug) appeared in the form of small dark osmiophilic vesicles located around the bile canaliculi of all hepatocytes (Fig. 1). These structures differed from the regular microbodies or the pericanalicular multivesicular bodies. They first appeared regularly rounded with electron dense matrix bound with a single membrane. After one week on the drug, these vesicles appeared vacuolated and resembled autophagosomes which soon developed whorls of concentric lamellae or cisterns characteristic of lysosomes (Fig. 2). These lysosomes were found, later on, scattered all over the hepatocytes.
Image Analysis of Electron Micrographs by Computor
Authors: Watanabe M. , Sasaki S. , Anasawa N. 
Published: June 2020

Since the electron microscope allows only a two-dimensional image of the specimen to be projected in the direction of the incident beam, it is difficult to represent a three-dimensional arrangement of the specimen substructure from an electron microscopic image. It is also difficult and troublesome to determine the inner specimen structure by means of electron diffraction due to its intrinsic nature. The same is ture of stereo electron microscopic technique. A new method by which one can derive detailed information on the three-dimensional structure of materials is of vital necessity.A method of quantitative determination of three-dimensional structure from electron microscopic images has been reported by De Rosier and Klug. This method makes it possible to derive from electron micrographs, the structures of micro specimens and bio-polymers inadequate for X-ray analysis.
Ciliated Granulosa Cells of the Bat, Myotis grisesoens
Authors: Appley Marlene B. , Richter Kenneth M. 
Published: June 2020

Ultrastructural study of the bat ovary reveals ciliated granulosa cells in follicles of all stages of development. Figs. 1-4 show a developmental range of follicles from the very youngest (Fig. 1) to the near or mature follicle (Fig. 4).The location and intracellular association of the cilia with the nucleus, Golgi complex and diplosome are the same in follicles of all degrees of development (Figs. 1-4). It seems significant that the cilium (c) of the granulosa cell is located consistently on that surface of the cell which is oriented toward the ovum (Figs. 1-4).The cilia have a fiber pattern of 9+0, in contrast to the usual 9+2 (Fig. 2). Cilia of this type have been found in a wide range of dissimilar organs. They are limited to metazoans. Their presence provides no clue to the origin of the granulosa cells, since all three germ layers may give rise to ciliated cells.
Retrieval of Paraffin Embedded Material for Ultrastructure Study
Authors: Clark T. S. , Rochlani S. P. 
Published: June 2020

With the increasing use of electron microscopy in pathology, there appears to be an equally increasing need for the utilization of paraffin embedded material for ultrastructure study. Several investigators! have identified viruses in retrieved material, but made little comment on the ultrastructure of the tissue or the techniques involved. It is erroneous to assume that tissue fixed in formalin has no value for the ultrastructure pathologist.We have analyzed the routine paraffin processed histological material to determine where and when loss of tissue and cell integrity occurs. In determining this site of “ultrastructure trauma” we have also tried various methods of retrieval of paraffin embedded material to prevent further loss of cellular structure.