bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of lipoyl-bearing domains in 2-ketoglutarate dehydrogenase complex by electron microscopy and single-particle averaging methods
Authors: Wagenknecht Terence , Frank Joachim
Published: June 2020

The 2-ketoglutarate dehydrogenase complex (KGDC) from E. coli (Mr=2.5 x 106) consists of multiple copies of three component enzymes. In addition to its catalytic function one of the components, dihydrolipoyl transsuccinylase (E2), serves as a structural core (Mr=l x 106) to which the other two components are noncovalently bonded. X-ray diffraction studies have shown the E2 complex to be built from 24 identical polypeptide chains and to have the overall shape of a cube having truncated corners. In the electron microscope the E2 complexes adhere preferentially to the support surface by one of their faces and thus appear square-shaped with four morphological units at the vertices and a stain filled center (Fig 1A).

Each of the E2 chains contains a lipoic acid cofactor covalently linked to a lysine residue. A domain (Mr=ll,000) containing the lipoyl moiety is removed by trypsin without disrupting the basic architecture of the complex. Micrographs of the trypsin-treated E2 complexes (Fig 1B) appear similar to those of the native complexes (Fig 1A), although the trypsintreated complexes appear slightly smaller and have a more sharply defined 4-fold symmetry.
Classification of electron microscopical images of randomly oriented bio macromolecules
Authors: van Heel Marin
Published: June 2020

New methods of image analysis in which aligned images of bio-macromolecules are submitted to multivariate statistical analysis in the form of correspondence analysis (CA) have largely facilitated the understanding of mixed populations of images. CA determines the main directions of interimage variance and gives the images new coordinates along the axes thus determined. A large reduction in the amount of data is obtained: instead of, for example, 64x64=4096 density values per image, each image is now characterized by eight factorial-axis coordinates at the most! The problem of classification of the images has therefore come closer; however, the essential final question still must be answered: " How does one objectively take images together in groups such that the classes of the 'partition' obtained represent the 'best' possible classification?" In the case of randomly oriented particles we would like the classes to contain only molecules in one particular orientation relative to the support film ("projection classes").
A structural study of modified fibrinogen and fibrin
Authors: Hewat E. A. , Tranqui L. , Wade R. H.
Published: June 2020

A knowledge of the form of the fibrinogen molecule and the structure of fibrin are clearly essential to the understanding of their role in the coagulation of vertebrate blood. The elongated multinodular form of the molecule is well established, but its detailed form and the structure of the fibrin fibre have remained controversial. Our approach to this problem has been firstly to examine the form of the molecule in several types of microcrystals of proteolytically modified fibrinogen. Tilting experiments enabled identification of the same molecular form in two different crystalline forms (P21212 and P21). Two projections of the molecule at 0° and at 37° to the 2-fold molecular axis were obtained from the two principal plane projections of the two crystal forms. This information enabled a rough determination of the relative heights of the different subdomains of the molecule. Hence we are able to propose a more detailed model of the fibrinogen molecule than has previously been reported.

Secondly, to clarify the existence of any differences between the native and the modified fibrinogen molecule, we examined individual molecules using negative staining and shadowing techniques.
Beryllium skin granuloma: Identification by electron energy loss spectroscopy
Authors: Mehard C. W. , Epstein W. L.
Published: June 2020

Understanding granulomatous inflammation includes the sequential biochemical and cytological changes which occur following tissue insult or injury. Granulomas may arise as a foreign body response to a colloidal substance involving a simple phagocytic process or as a hypersensitivity phenomena involving the reticuloendothelial system. We report here on the localization and detection of beryllium (Be) in Be-induced skin granulomas. Visualization and elemental analysis of Be, element number, was carried out by scanning transmission electron microscopy and electron energy loss spectroscopy.

Foreign body skin granulomas were produced by injecting beryllium lactate subdermally in the upper arms and shoulders of volunteers. Biopsies were taken 6-8 weeks later, fixed in 2% glutaraldehyde, dehydrated in ethanol and embedded in epon. Some specimens were post fixed in osmium tetroxide, dehydrated in a graded, series of ethanol and embedded in epon. Thin sections (500Å-2000Å) were viewed at 100 Kv, unstained in a Hitachi K-60G STEM, equipped with EDS and EELS.
Effects of ciglitazone on the pancreatic islets of C57BL/6J-OB/OB mice: Qualitative electron microscopy of beta cells and quantitative light microscopy of islet surface area and number
Authors: Peterson T. , Sawada G. , Wyse B. , Gilchrist B. , Diani A.
Published: June 2020

The Ob/Ob mouse of the genetic background C57BL/6J is characterized by obesity, hyperglycemia, insulin resistance, and hyperplasia of the pancreatic beta cells. Under electron microscopy, the beta cells from this animal model display degranulation, proliferation of the rough endoplasmic reticulum, and expansion of the Golgi apparatus, all of which are indicative of a stressed pattern of insulin storage and synthesis.

Ciglitazone has been reported to function as an oral hypoglycemic agent in the 0b/0b mouse. This depression of plasma glucose was associated with a significant elevation in pancreatic insulin as observed in our laboratory after six weeks of drug treatment (100 mg/kg-day incorporated into Purina Mouse Chow). Pancreatic islets of treated and age-sex matched control C57BL/6J-Ob/Ob mice were then analyzed by ultramorphology and light microscopy to determine the effect of ciglitazone on beta cells. Under electron microscopy, the pancreatic beta cells of treated mice were well granulated with rare abnormalities of the citoplasmic organelles and insulin secretory granules occupied most of the cytoplasm of the islet - cells.
An ultrastructural morphometric analysis of platelet giant and fusion granules in control subjects and patients with neoplastic myeloproliferative disorders
Authors: Payne Claire M. , Glasser Lewis
Published: June 2020

Electron microscopy has made a significant contribution to our understanding of the normal and defective human platelet. The normal human platelet is ultrastructurally complex and although only 2-4 microns in diameter, contains many cell organelles and structural elements shared with muscle cells and neurons. Platelet organelles include mitochondria, microfilaments, microtubules, α-granules (contain fibrinogen and platelet factor 4), dense bodies (contain serotonin, ADP, ATP and calcium), a dense tubular system and open canalicular system (Fig. 1). An ultrastructural description of giant granules were first reported in 1960 in Willebrand-Jürgens disease. Fusion granules (giant, irregularly-shaped granules) resulting from an apparent "fusion of normal-sized α-granules have since been reported to be characteristic of platelets obtained from patients with preleukemia and myelomonocytic leukemia.

Electron microscopic examination of normal platelets in our laboratory revealed occasional granules which also appear fused and irregular in shape.

A qualitative assessment of what constitutes an abnormal granule is therefore subjective. The purpose of this study was to establish morphometric criteria which can be used to define the pathological nature of giant and fusion-type platelet granules, and to determine if patients with neoplastic myeloproliferative disorders can be distinguished from patients with a variety of benign conditions for diagnostic purposes.
Z-line degradation and phagocytosis of sarcomeric fragments in myonecrosis
Authors: Estes Melinda L. , Chou Samuel M.
Published: June 2020

Many muscle diseases show common pathological features although their etiology is different. In primary muscle diseases a characteristic finding is myofiber necrosis. The mechanism of myonecrosis is unknown. Polymyositis is a primary muscle disease characterized by acute and subacute degeneration as well as regeneration of muscle fibers coupled with an inflammatory infiltrate. We present a case of polymyositis with unusual ultrastructural features indicative of the basic pathogenetic process involved in myonecrosis.

The patient is a 63-year-old white female with a one history of proximal limb weakness, weight loss and fatigue. Examination revealed mild proximal weakness and diminished deep tendon reflexes. Her creatine kinase was 1800 mU/ml (normal < 140 mU/ml) and electromyography was consistent with an inflammatory myopathy which was verified by light microscopy on biopsy muscle. Ultrastructural study of necrotizing myofiber, from the right vastus lateralis, showed: (1) degradation of the Z-lines with preservation of the adjacent Abands including M-lines and H-bands, (Fig. 1), (2) fracture of the sarcomeres at the I-bands with disappearance of the Z-lines, (Fig. 2), (3) fragmented sarcomeres without I-bands, engulfed by invading phagocytes, (Fig. 3, a & b ), and (4) mononuclear inflammatory cell infiltrate in the endomysium.
Possibility of Single Atom Resolution in Single-Sideband Imaging
Authors: Downin K. H.
Published: June 2020

The ability to distinguish between heavy and light components of a specimen, and especially to distinguish single heavy atoms, would be a great benefit in many instances. Even with the demonstrated ability of the STEM, and of the CTEM especially in dark field, to image single atoms, it is of interest to know the possibility of using bright field in a conventional microscope with subsequent image processing to obtain images of single heavy atoms separated from the image of a lighter supporting film.

Single-sideband image reconstruction, involving the combination of two images obtained using opposite halves of the diffraction pattern, offers in principle the ability to separate images of heavy and light specimen components, or specimen components giving rise to amplitude and phase contrast, respectively. This has been demonstrated in electron microscopy^, but under conditions or low resolution, where inelastic scattering, as well as scattering outside the effective objective aperture, contribute heavily to the component with amplitude contrast.
Lattice Imaging of Stacking Faults in (011) Silicon
Authors: Krivanek Ondrej L. , Maher Dennis M.
Published: June 2020

Thermal oxidation of silicon containing surface defects results in the formation of extrinsic stacking faults inhabiting the (111) planes. The faults are bound by Frank partial dislocations, and oxygen may be closely associated with them. The present work aims to explore the fault core structure by lattice imaging.

The p-type, 4 Ω-cm Si was boron implanted (50kV, 1x1015/cm2), annealed for 30 min at 1000°C and steam oxidized for 2 hours at 1050°C. The boron implantation prior to oxidation serves to produce a high density of stacking faults to facilitate their observation. The polished and thinned (011) foils were examined at 125kV in a Siemens 102 EM with a goniometer stage at magnifications of 500 000 to 800 000x, using axial illumination and no objective aperture.
Processing of STEM Images of Unstained Tropomyosin Magnesium Paracrystals
Authors: Golladay S.D.
Published: June 2020

The banding patterns of unstained tropomyosin magnesium paracrystals have been observed in a STEM at 30 kV. The microscope is interfaced to a computer so that both bright field and dark field (annular detector) signals can be stored on magnetic tape. The data acquisition system imposes constraints on the image sampling rate and on the maximum number of picture elements per frame, but has the substantial advantage of eliminating the need for careful film processing and densitometry for quantitative microscopy. The system is extremely helpful when first scan images of relatively thick objects on a thin carbon film are desired. In this situation, the operator cannot adjust the gain and bias of the video signal properly until he has already scanned the specimen. However, first scan data stored on magnetic tape can be replayed with bias and gain adjusted digitally to provide the best display of any specified region of interest in the image. Figure 1 shows such a replay of the bright field (IB) and dark field (1A) images of the paracrystal which was analyzed. The specimen was fixed and air dried but unstained.
Experiments with a Quadrupole Octopole Corrector in a STEM
Authors: Beck V.
Published: June 2020

Recently a number of experiments have been carried out on a STEM which included a multipole corrector for primary spherical aberration. The results of these experiments indicate that the correction of primary spherical aberration with magnetic multipoles is beset with very serious difficulties related to hysteresis.

The STEM and corrector have been described previously. In theory, the corrector should cancel primary spherical aberration so that other aberrations limit the resolution. For this instrument, secondary spherical aberration should limit the resolution to 1 A at 50 kV. A thorough study of misalignment aberrations was made. The result of the study indicates that the octopoles must be aligned to 1000 A. Since mechanical alignment cannot be done to this accuracy, trim coils were built into the corrector in order to achieve the required alignment electrically. The trim coils are arranged to excite all the lower order moments of an element.
Electron Optical Studies Of Catalyzed Gasification Of Graphite
Authors: Szirmae A. , Shirley C.G. , Fisher R.M.
Published: June 2020

The pronounced catalytic effect of small particles of iron and other elements and compounds on the reaction of carbonaceous solids with various gases (02, CO-CO2, H20-H2) has been documented by a number of investigators reporting on thermogravimetric studies on bulk samples (1,2) and on optical and electron microscope observations of pitting or surface channeling by rapid local attack adjacent to sub-micron iron particles (3,4). In this work, emphasis has been placed on detailed electron microscope studies of Fe particle channeling on graphite exposed to “wet” and “dry” hydrogen at temperatures from 650°C to 1200°C.

Flakes of freshly cleaved Ticonderoga graphite are coated with 40 - 1000 Å of Fe by vacuum deposition which forms spherical particles during subsequent annealing at 750°C.
Microdiffraction Calculations For Dislocations
Authors: Spence J.C.H.
Published: June 2020

The new generation of STEM instruments offer the possibility of recording the diffuse elastic scattering from the core region of an isolated dislocation. In order to use this information for core-structure analysis it is important to be able to compute this scattering including all dynamical and instrumental effects. Preliminary results of such a calculation using the multi-slice method of periodic continuation (1) are shown in figures 1-4 for the case of an end-on [100] undissociated edge dislocation in iron. Theoretical core atom coordinates (2) have been used to form a periodic array of dislocations as shown in figures 1 and 2. These atomic coordinates are calculated for a single isolated dislocation, however the scattering from the periodic array of dislocations shown closely approximates that from an isolated dislocation if the illuminating spot is small compared to the superlattice unit cell. No relaxation has been allowed in the beam direction.
The Application Of Weak Beam Transmission Electron Microscopy To The Study Of
Heterogeneous Precipitation On Dislocation Lines
Authors: Allen R.M.
Published: June 2020

Theoretical considerations indicate that the strain-sensitive nature of weak beam transmission electron microscopy warrants application of the technique to problems requiring the resolution of complex microstructures (1). Indeed, weak beam microscopy has already become a valuable tool for observing dislocation dissociation (1), crystalline interfaces (2), and fine precipitate structure (3). In this vein, experiments to determine the possible benefits of employing weak beam microscopy in the examination of heterogeneous nucleation on dislocation lines have been performed on samples of Al-3.87 wt.% Zn-1.79 wt.% Mg. Specimens were solutionized, lightly deformed, and then aged for various times at 150°C prior to observation.
Figure 1 is a comparison of a bright field and a weak beam micrograph taken of the same region in a sample aged 18 hrs. The precipitates are the stable η (MgZn2) phase.
The Suitability Of The Lattice Fringe Imaging Technique For Measuring Spatial Variation In Degree Of Long-Range Order In Fe-Al Alloys
Authors: Allen Samuel M.
Published: June 2020

A computer simulation of lattice fringe imaging of ordered Fe-Al alloys has been carried out, using the multiple beam dynamical theory of electron diffraction as formulated by Sinclair et al. for CU3AU (1). The object of the study was to determine the suitability of the lattice fringe imaging technique for studying spatial variations in long-range order parameter in singlephase ordered specimens.

In the interest of simplicity, the results of simulations in which eight beams were excited in the (200) systematic row for an imperfectly B2-ordered alloy of composition Fe-25% aluminum will be presented. (The prototype crystal structure for the FeAl phase is CsCl.) Simulated images were obtained by combining the direct beam with the (100) superlattice reflection, for the case in which Bragg's Law was satisfied for the (100) reflection, and with both beams equidistant from the optic axis of the microscope.

Image intensities as a function of distance parallel to [200] were computed for different specimen thicknesses and long-range order parameters.
Interpretation Of Dark FIELD IMAGES OF CRYSTALS
Authors: Iijima Sumio , O'Keefe M. A.
Published: June 2020

In order to determine whether image contrast of dark field images of crystals can be interpreted intuitively in terms of crystal structures, in the same way as for bright field images, observations and calculations have been made on the dark field images of a crystal of 4Nb205.9W03(Fig. 1, space group P21212, tetragonal tungsten bronze-type,a= 12.3,b= 36.6,c= 3.9Å). Disorder in this crystal will be duscussed elsewhere (IT). To verify the present state of the art of theoretical interpretation of bright field images, we compared an experimental structure image (Fig. 3a) with one calculated (Fig. 3b) taking into account various parameters including the beam divergence. Low resolution images were also compared (Figs. 3c,d). Matching between the images is satisfactory. From this basis we developed a computer program for dark field images of crystals.

To simplify the interpretation we confine ourselves here to low resolution images, i.e., number of beams contributing to the image is less than 15 (position of the objective aperture is indicated in the E.D. pattern of Fig. 2a).
Effect of Annealing Temperature on the Structure of Al-Hf Films
Authors: Smith P. J. , Howard J. K.
Published: June 2020

The Al-Hf reaction is important because of the electromigration properties of Al-Hf thin-film conductors and because of the possible effect of the reaction on the barrier height of Hf Schottky barrier diodes (1). Previous studies of Al-Hf films had shown that the final structure was dependent on the grain structure of the A1 layer (2). When Hf was in contact with a largegrained A1 layer, Al3Hf formed as precipitates at A1 grain boundaries; when Hf was in contact with a fine-grained A1 layer, a continuous layer of Al3Hf formed at the Al-Hf interface. In the present work we show that, by varying the importance of A1 diffusion through Hf relative to Hf diffusion through Al, the annealing temperature influences both the overall film structure and the Al-Hf atomic ratio at the bottom surface. A 6000-Å-thick layer of Al was deposited on 1000 Å of Hf;
Scanning Electron Microscopy of Human Jejunum in Whipple's Disease
Authors: Watson John H. L. , Sun C. N.
Published: June 2020

That the etiology of Whipple's disease could be bacterial was first suggested from electron micrographs in 1960. Evidence for binary fission of the bacteria, their phagocytosis by histiocytes in the lamina propria, their occurrence between and within the cells of the epithelium and on the brush border of the lumen were reported later. Scanning electron microscopy has been applied by us in an attempt to confirm the earlier observations by the new technique and to describe the bacterium further. Both transmission and scanning electron microscopy have been used concurrently to study the same biopsy specimens, and transmission observations have been used to confirm those made by scanning.

The locations of the brush borders, the columnar epithelial cells, the basement membrane and the lamina propria beneath it were each easily identified by scanning electron microscopy. The lamina propria was completely filled with the wiener-shaped bacteria, Fig. 1.
Biological and Surface Properties of C-Type Virus Particles Produced by Novikoff Ascites Hepatoma Cells
Authors: Hixson D.C. , Chan J.C. , Bowen J.M. , Walborg E.F.
Published: June 2020

Several years ago Karasaki (1) reported the production of type C virus particles by Novikoff ascites hepatocarcinoma cells. More recently, Weinstein (2) has reported the presence of type C virus particles in cell cultures derived from transplantable and primary hepatocellular carcinomas. To date, the biological function of these virus and their significance in chemically induced hepatocarcinogenesis are unknown. The present studies were initiated to determine a possible role for type C virus particles in chemically induced hepatocarcinogenesis. This communication describes results of studies on the biological and surface properties of type C virus associated with Novikoff hepatocarcinoma cells.

Ecotropic and xenotropic murine leukemia virus (MuLV) activity in ascitic fluid of Novikoff tumor-bearing rats was assayed in murine sarcoma virus transformed S+L- mouse cells and S+L- mink cells, respectively. The presence of sarcoma virus activity was assayed in non-virus-producing normal rat kidney (NRK) cells. Ferritin conjugates of concanavalin A (Fer-Con wheat germ agglutinin (Fer-WGA), and Ricinus communis agglutinins I and II (Fer-RCAI and Fer-RCAII) were used to probe the structure and topography of saccharide determinants present on the viral envelope.
Intranuclear Crystals in Epithelial Cells of Perca Flavescens
Authors: Leino Richard L.
Published: June 2020

During microscopic examination of tissues of healthy-appearing perch caught in N.E. Minnesota lakes, it was noticed that the specimens frequently had variable numbers of epithelial cells whose nuclei contained eosinophilic inclusion bodies. These nuclear inclusions were found in a number of sites: surface epithelial cells of gill, skin and distal rectum; columnar cells of kidney collecting ducts; taste bud cells and, rarely, chloride cells of gill. In addition, the inclusions were found in rodlet cells in all of these regions, but not in rodlet or other epithelial cells of intestine. Under the electron microscope, these nuclear inclusions appear as 4-, 5-, and 6-sided paracrystals ranging in length from less than 0.5 μm to greater than 3 μm. The inclusions are usually surrounded by a narrow rim of electron-lucent nucleoplasm. Some crystals are composed of circular subunits hooked together (?) in parallel rows.
Immunocytochemical Localization of Amyloid Protein AA in the “Dense Fibrillar Inclusions” of the Reticuloendothelical Cells
Authors: Shirahama T. , Skinner M. , Cohen A.S.
Published: June 2020

A1thought the mechanisms of amyloidogenesis have not been entirely clarified, proteolysis of the parent proteins may be one of the important steps in the amyloid fibril formation. Recently, we reported that "dense fibrillar inclusions" (DFI), which had the characteristics of lysosomes and contained organized fibrillar profiles as well, were observed in the reticuloendothelial cells in close association with the foci of new amyloid deposits. We considered the findings as evidence for the involvement of lysosomal system in amyloid fibril formation (l). In the present study, we attempted to determine the identity of the contents of the DFI by the use of antisera against the amyloid protein (AA) and an immuno-electron microscopic technique.

Amyloidosis was induced in CBA/J mice by daily injections of casein (l). AA was isolated from amyloid-laden spleens by gel filtration and antibody to it was produced in rabbits (2). For immunocytochemistry, the unlabeled antibody enzyme method (3) was employed.
Visualization of the Platelet-Plasma Interface
Authors: Brindley D. C. , McGill M.
Published: June 2020

Morphological and cytochemical studies of platelets have reported a surface coat, or glycocalyx, external to the plasma membrane (1). Biochemical analyses have likewise confirmed the highly adsorptive properties of platelets as transporters of coagulation factors (2). However, visualization of the platelet membrane by conventional EM procedures does not reflect this special relationship between the platelet and its plasma environment. By the routine method of alcohol-propylene oxide dehydration for Epon embedding, the lipid bilayer nature of the platelet membrane appears similar to other blood cells (Fig. 1). A new rapid embedding technique using dimethoxypropane (DMP) as dehydrating agent (13) has permitted ultrastructural analyses of the surface features of the platelet-plasma interface.

Aliquots of human or rabbit platelet-rich plasma (PRP) were added to equal volumes of 6% glutaraldehyde in Millonig's buffer at 37° for 45 minutes, rinsed in buffer and postfixed in 1% osmium in Millonig's buffer for 45 minutes.
Spontaneous Cataract in Nude Athymic Mice
Authors: Bradley Ronald H. , Berk R. S. , Hazlett L. D.
Published: June 2020

The nude mouse is a hairless mutant (homozygous for the mutation nude, nu/nu), which is born lacking a thymus and possesses a severe defect in cellular immunity. Spontaneous unilateral cataractous lesions were noted (during ocular examination using a stereomicroscope at 40X) in 14 of a series of 60 animals (20%). This transmission and scanning microscopic study characterizes the morphology of this cataract and contrasts these data with normal nude mouse lens.

All animals were sacrificed by an ether overdose. Eyes were enucleated and immersed in a mixed fixative (1% osmium tetroxide and 6% glutaraldehyde in Sorenson's phosphate buffer pH 7.4 at 0-4°C) for 3 hours, dehydrated in graded ethanols and embedded in Epon-Araldite for transmission microscopy. Specimens for scanning electron microscopy were fixed similarly, dehydrated in graded ethanols, then to graded changes of Freon 113 and ethanol to 100% Freon 113 and critically point dried in a Bomar critical point dryer using Freon 13 as the transition fluid.
Ultrastructural Studies of Acute Rheumatic Valvulitis
Authors: Siew S.
Published: June 2020

The advent of cardiac surgery has accorded the opportunity of obtaining fresh human tissue suitable for electron microscopy. The percentage of acute rheumatic lesions in such material is understandably small and there has been comparatively little progress with the ultrastructural investigation of this stage of the disease. This report presents the transmission and scanning electron microscopic findings of 3 cardiac valves: a mitral, a tricuspid and an aortic, which had been resected on the basis of the clinical diagnoses of mitral stenosis, tricuspid stenosis and aortic insufficiency, respectively. Gross and histological examination showed the classical features of acute and chronic rheumatic valvulitis.

Transmission electron microscopy was performed on the valves and on the related structures of the atrio-ventricu1ar valve mechanism, the chordae tendineae and the papillary muscles. The valves were thickened and showed the presence of abundant collagen, some elastic tissue and foci of calcification.
Hepatic Ultrastructure in Methotrexate Treated Psoriatic Patients
Authors: Horvath E. , Kovacs K. , Ross R. C. , Kerenyi N. A. , Saibil F. G.
Published: June 2020

Fifty liver biopsies of psoriatic patients treated with methotrexate, a folic acid antagonist, for a period from a few weeks up to 15 years have been studied. Liver tissue has been obtained by percutaneous biopsy with a Menghini needle and prepared for electron microscopy by using conventional techniques.

In the hepatocytes, profound changes have been revealed in four areas: nucleus, mitochondria, ectoplasmic zone-cell membrane and desmosomes. The nuclei showed reduced electron opacity and almost complete absence of heterochromatin. Cytoplasmic invaginations and glycogen inclusions were common. Mitochondrial pleomorphism, paracrystalline inclusions and giant mitochondria were prominent findings. Compartmentalization, fission and division of mitochondria were also noted. Sequestration of mitochondria via development of cytosegresomes was observed in several cases. Detachment of desmosomes was a conspicuous finding in 25 of 50 biopsies obtained from methotrexate-treated psoriatics. In these livers many or practically all membrane sites with desmosomal specialization appeared to be pulled apart.
Ultrastructural Study of Peroxisomes in Human Hepatocytes of a Chronic Alcoholic
Authors: Lim B.S.
Published: June 2020

Peroxisomes in normal human hepatocytes are catalase-containing rounded or oval organelles with an average diameter of 0.63 μm (l). They are usually surrounded by single tripartite membranes. Their presence can be easily demonstrated by the use of 3,3' diaminobenzidine (DAB) stain in the presence of H202 (2). This paper represents an ultrastructural study of peroxisomes in tne liver biopsy of an alcoholic patient with preoperative diagnosis of fatty infiltration.

Biopsy tissues were fixed in 5% glutaraldehyde in 0.1 M phosphate buffer (pH 7.4), postfixed in 1% OsO4 and embedded in epoxy resin. Thin sections were stained with lead citrate and uranyl acetate and examined with a Zeiss EM 9 S-2.

Light microscopic study of the liver biopsy reveals an intact hepatic architecture. The hepatocytes appear slightly edematous and possess many eosinophilic granules.

Electron microscopy (Fig l) reveals that there is a marked increase in the number of randomly distributed peroxisomes in alcoholic human hepatocytes.
Ultrastructure of 2-Bromergocryptine-Treated Human Prolactin-Secreting Microadenomas in Culture
Authors: Bredesen D.E. , Schomberg D. , Kramer R. , Hammond C. , McCarty K.S.
Published: June 2020

Speculation concerning the mechanism by which 2-bromoergocryptine (CB 154) acts to decrease serum prolactin (PRL) levels has revolved around two basic hypotheses; one concerning the importance of primary hypothalamic effects; the other emphasizing direct hypophyseal effects. The potential for hypothalamic effects were reduced in these experiments by explanting PRL-secreting microadenomas in organ culture and short term monolayer tissue culture. Tissue was obtained immediately from the operating room from 6 patients operated on by the transphenoidal approach. Cultures were maintained in Ham's F12 Nutrient Medium, 90% by volume with 10% fetal calf serum. CB 154 was added at concentrations of 0, 0.5, or 5.0μg/ml. The organ cultures were maintained for 24 hours before the addition of CB 154 and then for 24 to 48 hours in the presence of inhibitor after which specimens were fixed at 4°C with 4% glutaraldehyde, 0.1M. Cacodylate, pH 7.2, and post-fixed with 1% osmium tetroxide.
Contrast Enhancement of Fresh Frozen-Dried Tissue for Light and Electron Microscopy
Authors: Bankston Patrick W. , Terracio Louis
Published: June 2020

Recent improvements in the technique of freeze-drying now routinely provide biological tissues with morphological preservation ultrastructurally comparable to conventionally-fixed tissue. Using this technique, tissue is frozen on a metal surface, dried in vacuo, vapor fixed with OSO4 and directly embedded in polymers suitable for sectioning for light or electron microscopy. Tissue processed in this manner can be used for such specialized applications as x-ray microanalysis and radioautography of soluble substances. Further, it is possible to eliminate OSO4 before embedding making frozen-dried tissue useful for investigation of cellular components by cytochemical reactions performed on sectioned material. Many of these procedures require that the tissue be free of OSO4 initially but that OSO4 be present for final viewing. In addition, frozen-dried tissue requires preliminary viewing in the light and electron microscopes to evaluate the extent of ice crystal damage before use for specific reactions. However, it is difficult to stain unfixed plastic embedded tissue for light microscopy and equally difficult to provide adequate contrast to these for electron microscopy.
Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections
Authors: Glaeser Robert , Bauer Thomas , Grano David
Published: June 2020

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.
A Freeze Fracture Preparation Chamber Attached to the SEM
Authors: Pawley J. B. , Hayes T. L.
Published: June 2020

The freeze fracture technique has developed into a standard tool of biological electron microscopy particularly for the study of membrane surfaces. While permitting high resolution (2.5 nm) study of replicated specimens, freeze fracture has always had certain technical limitations: 1) The carbon and platinum replicas are extremely fragile and much care and patience are required to prepare them for EM observation. This is particularly true when large areas must be replicated or when complementary replicas are required. 2) The carbon and platinum replica despite its very “real” appearance is not the actual sample. The sample itself has been completely destroyed in preparing the replica and can neither be subjected to chemical element analysis nor reprocessed for any sort of subsequent study. 3) The investigator can neither monitor the fracture process nor make a subsequent fracture of the same sample.
Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast
Authors: Keyhani E.
Published: June 2020

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).

Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).
Fine Structure of Oogenesis in the Snail Tarebia Granifera (Melaniidae)
Authors: Matthes Michael T. , Blystone Robert V.
Published: June 2020

The ovary of the fresh-water snail, Tarebia granifera, is found in the caudal upper whorls of the shell. Careful dissection was required to separate the ovary from the digestive gland which shared a common epithelial covering with the ovary. The ovarian tissue was fixed in sodium cacodylate buffered 3% glutaraldehyde, post-fixed in 1% osmium tetroxide, en bloc stained with 0.5% uranyl acetate, dehydrated, and embedded in Epon-Araldite plastic.

This study indicated that oocytes of T. granifera were found only in prophase stages of maturation along the length of the ovarian tube. A similar observation has been documented for the closely related snail Melanoides. The T. granifera oocytes were situated in the ovary in such a way that the immature early prophase oocytes were found near the outer ovarian wall and the more mature late prophase oocytes were seen developing toward the center of the ovarian tubular structure.
Ultrastructure of the Parotid Gland of the Nine-Banded Armadillo
Authors: Ruby J. R.
Published: June 2020

Parotid glands were obtained from five adult (four male and one female) armadillos (Dasypus novemcinctus) which were perfusion-fixed. The glands were located in a position similar to that of most mammals. They extended interiorly to the anterior portion of the submandibular gland.

In the light microscope, it was noted that the acini were relatively small and stained strongly positive with the periodic acid-Schiff (PAS) and alcian blue techniques, confirming the earlier results of Shackleford (1). Based on these qualities and other structural criteria, these cells have been classified as seromucous (2). The duct system was well developed. There were numerous intercalated ducts and intralobular striated ducts. The striated duct cells contained large amounts of PAS-positive substance.

Thin sections revealed that the acinar cells were pyramidal in shape and contained a basally placed, slightly flattened nucleus (Fig. 1). The rough endoplasmic reticulum was also at the base of the cell.
Inelastic Scattering and Electron Spectroscopy
Authors: Jouffrey B.
Published: June 2020

The reasons for studying energy losses can be quite different. The motivations are often highly diversified even if searchers are electron microscopists
For instance, the problem of useful penetration involves studying the question of chromatic blurring even if in many cases this effect is not sufficient for explaining the limitations in penetration. The formation of damage (direct knock-on and ionization) is interesting in many ways.
In electron microscopy an important point is also the contrast preservation in an inelastic event. This point is related to the useful penetratior (principally in crystalline materials). If that is rather well understood in the case of potentials which are not localized (1) (plasmons and single quasi free electron excitations), it is not so clear in the case of localized interactions as electron phonon ones (2,3,4) or inner shell excitations even if the scattering angle is quite small. However the understanding of this contrast preservation is fundamental.
Incorporation of the automated tissue processing system in biological electron microscopy—a further critical evaluation
Authors: Aihara Kaoru , Suzuki Katsuya , Hirohata Yasuhisa , Yajima Mioko , Yajima Gonpachi , Hata Toshio , Goro Asano , Matsumoto Keiko , Kurokawa Taneomi , Takahashi Kikuo , Mori Hidekatsu , Tsuzuki Takashi
Published: June 2020

Objective: In reviewing the attempt to incorporate the automated tissue processing system in the diagnostic or clinical electron microscopic investigation to relief the paintaking harmfull manipulation of the chemicals and for the safety management of the laboratory persons, the authors inclined to make a few introductory remarks on this matter. one has been developed by Dr.Norris and Dr.Banfield in the U.S.A.,N.I,H.group, and the other has been developed by our group which is hitherto reported and designated as Aihara Processor. The present communication is dealing with the further development of the automated processing with emphasis on its versatility in the efficient laboratory management. Historically: i)Norris processor ii)Benjamin processor and iii)Aihara processors are developed and currently be available for use.

Mechanical principle of the automated tissue processing device: The basic principle is adapted from the automated tissueprocessing device from the light microscopic tissue preparation. The prototype is basically adapted from from the rolling type turntable which accomodate the specimen holder which is cover by plastic dome in entirety.
Contamination of thin sections, cause and elimination
Authors: Mollenhauer Hilton H. , James Morré D.
Published: June 2020

Contamination of thin sections is a problem that has undoubtedly been experienced by most, if not all, electron microscopists. By section contamination, we refer to any extraneous material in, or on, a thin section. Section contamination is not only a nuisance to the investigator but a serious waste of time and a possible cause of image misinterpretation. Section contamination usually appears sporatically and can often be solved by changes in the fixation, embedding, or staining procedures. However, the true cause of section contamination is only occasionally identified. Four types of section contamination are described in this report along with potential causes and remedies.

SURFACE CONTAMINATION is defined as any extraneous material on the surface of a section. Surface contamination occurs during the poststaining procedure and is perhaps the most common and easiest to recognize of the four section contaminations being discussed. Sections look "dirty" and the contaminating particles may be both large and dense.
Electron microscopic analysis of objects in light microscopic sections
Authors: Maunsbach Arvid B.
Published: June 2020

Structural studies in experimental biology or in pathology are frequently extended from the light to the electron microscopic level. This is often done by cutting both semithin (about 1 μm) and thin sections from the same tissue block after embedding for electron microscopy. However, in many studies it would be of great value to analyse the same structure both by light and electron microscopy, i.e. to be able to study by electron microscopy an object which is first detected by light microscopy in a semithin section. To achieve this, a method has been developed by which ultrathin sections are cut directly from the semithin section containing the object of interest.

Semithin sections, about 1 μ in thickness, are cut from Epon or Vestopal embedded tissue. The sections are placed on ordinary glass slides and stained with toluidine blue. The sections are studied in the light microscope without a cover glass or mounted in water.
Localization of pancreatic enzymes in ultrathin frozen sections stained with metal labeled antibody
Authors: Yasuda Kenjiro
Published: June 2020

Localization of amylase,chymotrypsinogen and trypsinogen in pancreas was demonstrated by Yasuda and Coons (1966), by using fluorescent antibody method. These enzymes were naturally found in the zymogen granules. Among them, amylase showed a diffuse localization around the nucleus, in addition to the zymogen granules. Using ferritin antibody method, scattered ferritin granules were also found around the Golgi area (Yasuda et al.,1967). The recent advance in the tissue preparation enables the antigen to be localized in the ultrathin frozen sections, by applying the labeled antibodies onto the sections instead of staining the tissue en bloc.

The present study deals with the comparison of the localization of amylase and lipase demonstrated by applying the bismuth-labeled, peroxidase-labeled and ferritin-labeled antibody methods on the ultrathin frozen sections of pancreas, and on the blocks of the same tissue.
A new technique for preparation of beverage samples for asbestos measurement by electron microscopy
Authors: Chatfield E.J.
Published: June 2020

Quantitative evidence on the health risks associated with gastrointestinal exposure to asbestos fibres is somewhat deficient, although an excess incidence of gastrointestinal carcinoma has been demonstrated in the case of occupational exposure. The use of chrysotile asbestos as a filter medium for clarification or sterilization of some beverages has thus led to a requirement for analytical techniques for fibre concentration measurement in these liquids.

A technique has been described in which the liquid is passed through a membrane filter; this is then ashed and the residue redispersed ultrasonically in fibre-free water. A few microlitres of the resulting suspension are evaporated to dryness on a carbon-coated TEM grid, and fibres are counted on a few grid openings. The high organic content of some beverages, however, often prevents filtration of an adequate volume through a membrane filter of a realistic pore size. Pectins, yeast cells and bacteria are the principal components responsible.
Ca-Histochemistry in slime mold plasmodia
Authors: Dierkes Ulrich
Published: June 2020

Calcium is supposed to play an important role in the control of protoplasmic streaming in slime mold plasmodia. The motive force for protoplasmic streaming is generated by the interaction of actin and myosin. This contraction is supposed to be controlled by intracellular Ca-fluxes similar to the triggering system in skeleton muscle. The histochemical localisation of calcium however is problematic because of the possible diffusion artifacts especially in aquous media.To evaluate this problem calcium localisation was studied in small pieces of shock frozen (liquid propane at -189°C) plasmodial strands of Physarum polycephalum, which were further processed with 3 different methods: 1) freeze substitution in ethanol at -75°C, staining in 100% ethanol with 1% uranyl acetate, and embedding in styrene-methacrylate. For comparison the staining procedure was omitted in some preparations. 2)Freeze drying at about -95°C, followed by immersion with 100% ethanol containing 1% uranyl acetate, and embedding. 3) Freeze fracture, carbon coating and SEM investigation at temperatures below -100° C.
X-ray microanalysis of frozen-hydrated bulk biological specimens: fundamental considerations
Authors: Low W.C. , Burgio P.A. , Allard L.F. , BeMent S.L. , Bigelow W.C. , Lawrence M.
Published: June 2020

X-ray microanalysis and scanning electron microscopy used in conjunction with cold-stage techniques to examine frozen-hydrated bulk biological tissue is a promising method to determine the concentration and distribution of diffusible elements which are typically distorted by conventional techniques of biological tissue fixation. The proper application of this method, however, requires an understanding of the freezing and sublimation processes in bulk biological specimens, and the interaction of the electron beam with the bulk specimen in the frozen-hydrated state. These factors have been evaluated and are discussed below.

One of the fundamental considerations in the examination of cryofixed bulk tissue is the formation of exogenous and endogenous ice crystals within the specimen or upon the surface of the specimen which can lead to tissue distortion and ion translocation. Techniques to minimize the exposure of the specimen to atmospheric conditions and to eleminate the formation of exogenous ice crystals have been developed by Burgio et al. (1978a), and Echlin and Moreton (1974).