bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative EM of gap junction distribution in mutant drosophila wing discs
Authors: Ryerse J.S. 
Published: June 2020

Gap junctions are intercellular junctions found in both vertebrates and invertebrates through which ions and small molecules can pass. Their distribution in tissues could be of critical importance for ionic coupling or metabolic cooperation between cells or for regulating the intracellular movement of growth control and pattern formation factors. Studies of the distribution of gap junctions in mutants which develop abnormally may shed light upon their role in normal development. I report here the distribution of gap junctions in the wing pouch of 3 Drosophila wing disc mutants, vg (vestigial) a cell death mutant, 1(2)gd (lethal giant disc) a pattern abnormality mutant and 1(2)gl (lethal giant larva) a neoplastic mutant and compare these with wildtype wing discs.The wing pouch (the anlagen of the adult wing blade) of a wild-type wing disc is shown in Fig. 1 and consists of columnar cells (Fig. 5) joined by gap junctions (Fig. 6). 14000x EMs of conventionally processed, UA en bloc stained, longitudinally sectioned wing pouches were enlarged to 45000x with a projector and tracings were made on which the lateral plasma membrane (LPM) and gap junctions were marked.
Radiation Damage in Amorphous Nb40Ni60
Authors: Rechtin M. D. , Vander Sande J. , Baldo P. M. 
Published: June 2020

We have performed a study of displacement radiation damage in a relatively new type of material, the noncrystalline refractory-transition metal Nb40Ni60. This alloy has a crystallization temperature of ˜1000 K, and therefore exhibits excellent thermal stability; it also has a high microhardness and shows good ductility. This material was prepared by a splat-quenching method and properties of this alloy are discussed in detail in Ref. 1.We have simulated the effects of fast-neutron displacement-induced damage by a 3.5-MeV Ni+ beam that has a displacement per atom rate of ˜3 x 10-3 dpa/s. As shown in Fig. 1, the Ni+ ions have a range of ˜0.8 μm and a peak in induced damage at 0.65 μm as calculated by the Brice Code.2 This result is based on a weighted average of the elemental crystalline densities, and variations in packing density of about ±15% alter the location of peak damage only ±0.1 μm.
Fine Structure of Interfaces as Revealed by Lattice Fringe Imaging
Authors: Sinclair R. 
Published: June 2020

Interfaces play a critical role in determining the ultimate macroscopic properties of many materials. Their presence of course can be detected by conventional microscopy methods. However, many of the phenomena associated with interfaces still lack a basic understanding in terms of fine structure and this is clearly an area to which high resolution TEM techniques can be applied. Definite progress has been achieved recently and this paper reviews the contributions made by lattice fringe imaging.It is well-known that the experimental conditions for obtaining lattice images are quite stringent. This is even more the case if two or more crystal orientations or phases are involved. For instance a grain boundary separates two crystals whose orientations are in general random with respect to the electron beam.
An Improved Quantitative Image Analyser
Authors: Fallon J.P. , Gregory P.J. , Taylor C.J. 
Published: June 2020

Quantitative image analysis systems have been used for several years in research and quality control applications in various fields including metallurgy and medicine. The technique has been applied as an extension of subjective microscopy to problems requiring quantitative results and which are amenable to automatic methods of interpretation.Feature extraction. In the most general sense, a feature can be defined as a portion of the image which differs in some consistent way from the background. A feature may be characterized by the density difference between itself and the background, by an edge gradient, or by the spatial frequency content (texture) within its boundaries. The task of feature extraction includes recognition of features and encoding of the associated information for quantitative analysis.Quantitative Analysis. Quantitative analysis is the determination of one or more physical measurements of each feature. These measurements may be straightforward ones such as area, length, or perimeter, or more complex stereological measurements such as convex perimeter or Feret's diameter.
On the Origin of the Microscystalline Structure in Rapidly Solidified IN-100 Powder
Authors: Walsh J. M. , Gumz K. P. , Whittles J. C. , Kear B. H. 
Published: June 2020

During a routine examination of the microstructure of rapidly solidified IN-100 powder, produced by a newly-developed centrifugal atomization process1, essentially two distinct types of microstructure were identified. When a high melt superheat is maintained during atomization, the powder particles are predominantly coarse-grained, equiaxed or columnar, with distinctly dendritic microstructures, Figs, la and 4a. On the other hand, when the melt superheat is reduced by increasing the heat flow to the disc of the rotary atomizer, the powder particles are predominantly microcrystalline in character, with typically one dendrite per grain, Figs, lb and 4b. In what follows, evidence is presented that strongly supports the view that the unusual microcrystalline structure has its origin in dendrite erosion occurring in a 'mushy zone' of dynamic solidification on the disc of the rotary atomizer.The critical observations were made on atomized material that had undergone 'splat-quenching' on previously solidified, chilled substrate particles.
Ultrastructural Studies on Genital Infection with the Chlamydial Agent of Guinea Pig Inclusion Conjunctivitis
Authors: Soloff B. L. , Barron A. L. , White H. J. , Rank R. G. 
Published: June 2020

Chlamydial organisms (specifically C. trachomatis) have been implicated as a frequent cause of genital infection in the human (1). Study of the histo- pathological aspects of such infections has been impeded because of difficulties in obtaining adequate tissue specimens and the lack of a suitable experimental host. In 1964, Murray (2) isolated the causative agent of guinea pig inclusion conjunctivitis which possesses similarities to human inclusion conjunctivitis. This guinea pig organism was found to be a member of the Chlamydia psittaci subgroup and was designated as the Gp-ic agent. Male guinea pigs have been successfully infected with Gp-ic by intraurethral inoculation. Transmission of the infection to the female by sexual contact has been demonstrated (3). We are not aware of any ultrastructural studies to date concerning the development of this agent in genital tissue.Studies in our laboratory have established that, in our guinea pig model, the cervix is the major site of injection.
Annulate Lamellae in Human Tumor Cells
Authors: Sun C. N. , White H. J. 
Published: June 2020

Annulate lamellae seem to have a widespread occurrence in animal tumor cells; however, presence in human neoplastic material has been reported in only a few cases (1,2). Recently, we found these structures from biopsies of cerebellar metastatic carcinoma, testicular seminoma, retinoblastoma and in three melanomas.These annulate lamellae are arranged in stacked parallel arrays in the cytoplasm of tumor cells. In some cases, annulate lamellae have been found in contact with the nuclear envelope. The number of annulate lamellae observed to comprise a single stack varies from 5-18 in the cerebellar tumors (Fig. 1), 2-4 in the seminoma (Fig. 2), 2-8 in the retinoblastoma and 8-10 in the melanomas (Fig. 3). All the lamellae structures are connected with the rough endoplasmic reticulum. By appropriate section, "pores" on the membranes are seen which have an outside diameter of approximately 1000 - 1600 A.
Endogenous Peroxidase Localization in Kupffer Cells of the Fetal Rat Liver
Authors: Pino Richard M. 
Published: June 2020

This study confirms the presence of endogenous peroxidase in fetal Kupffer cells. In adult hepatic sinusoids Kupffer cells are peroxidase positive; endothelial cells are not.1 The fetal rat liver sinusoidal endothelium during development changes from a lining similar to that found in adult bone marrow to an adult liver type.2 Cells that resemble adult Kupffer cells are evident at 13 days gestation and can endocytize carbon beginning at 14 days.Sixteen day Wistar rat fetuses were exposed in utero after ether anesthesia of their mothers. Colloidal carbon (Pelikan, Gunther Wagner) diluted 1:1 with double strength Tyrode1s solution, or as a control, single strength Tyrode's solution without carbon, was injected (0.01-0,03ml) into the fetal umbilical veins with a 30 gauge needle.2 After allowing one minute for the injected material to circulate, the fetuses were decapitated and the livers were removed and diced into small pieces.
Tannic Acid as Fixative and Stain for Amyloid Tissues
Authors: Rodgers O. G. , Shirahama T. , Cohen A. S. 
Published: June 2020

Amyloid is a protein deposited in a variety of organs in the disorder amyloidosis which is widely distributed in the animal kingdom. The identification of this substance and diagnosis of the disease is largely dependent on its morphologic characteristics and tinctorial properties by light microscopy and the fibrillar structure by electron microscopy (1). In electron micrographs prepared conventionally, very often the amyloid fibrils show low electron density, making it difficult to identify small airyloid deposits when scanning by low magnification, and difficult to analyze ultrastructural details at high magnification. After testing various fixatives and stains to achieve good fixation and staining of the anyloid fibrils, we have found that the use of tannic acid as a fixative (2) may satisfy these objectives.Various tissues (skin, tongue, prostate, spleen, liver and kidney) were obtained at biopsy, surgery or autopsy from patients with primary, secondary, myelcma-associated or hereditary amyloidosis. Spleen, liver and kidney from CBA/J mice in which amyloidosis was induced by daily casein injections were also used.
Freeze Fracture Studies of Particle Segregation in Compacted Myelin
Authors: Benitez C. , Caspar D.L.D. , Kirschner D.A. 
Published: June 2020

The membrane faces of the myelin of fresh-frozen sciatic nerve exhibit small uniformly distributed particles1. We have found that particle aggregation over large areas of the membrane faces, showing extensive intermembrane correspondence, can be induced by treatment with dimethylsulfoxide, polyethylene glycol, acetone, sodium chloride, calcium chloride, and by dehydration at high or low relative humidity. A similar but transient aggregation is induced by brief exposure to glycerin. Observations on optic nerve and brain white matter indicate that central nervous system myelin is affected in a manner similar to peripheral nervous system myelin.With these treatments the myelin generally was not grossly disrupted and the lamellae were well ordered. Two distinct membrane populations were clearly seen (Fig. 1). The particle-rich membrane population had a rough appearance in cross fracture and a period of about 180Å. The smoother, relatively particle-free membrane had a period of about 125-135Å.
Serial Section Analysis of Acrosomal Complex in Late Phases of Spermiogenesis of Acrida Lata Motschulsky (Orthoptera)
Authors: Yasuzumi G. , Matano Y. , Sakai T. , Shimakura S. 
Published: June 2020

Although considerable attention has been paid to the formation of acrosomal complex and its mature form in several families of Orthoptera (1, 2, 3, 5, 6), the relationship between the acrosomal membrane (5) and the acrosome proper remains as yet unsettled. To gain an insight into several problems of induction for sper- miogenesis, electron microscopy of serial sections is required. Serial sections of 30-60 nm thick are of value in establishing the reality of presumable membrane continuities.The testis of the grasshopper, Aovida lata Motschulsky, was fixed with a triple fixation procedure (4). The fixed specimens were embedded in epoxy Epon resin by a routine method for electron microscopy. The tissue was sectioned with diamond knives on an LKB ultrotome. The serial sections in this study were at flat gray reflection color (30-60 nm in thickness). Serial sections were placed on 100-mesh copper grids. They were stained doubly with uranyl acetate followed by lead citrate.
Scanning Electron Microscopy of the Male Nematode Physaloptera (Tetradelphynema)
Authors: Behbehani Bahja I. , Nayak Ramesh K. , McCoy Randall E. 
Published: June 2020

Nematodes are elongate, unsegmented worms with an elastic cuticle made of protein. Few published references concerning scanning electron microscopy of nematode are available and there is paucity of information at the ultrastructural level on cuticle forming male reproductive structures. The species of the genus Physaloptera (tetradelphynema) commonly live as parasites in the adult form in the stomach of the desert rodent Gerbillus cheesmani. To date, the three-dimensional surface features of this spiruroid nematode have not been described. The main purpose of this investigation was to elucidate the surface features of the male nematode utilizing the current techniques of scanning electron microscopy.Adult worms were collected in the laboratory from the stomach of the gerbil, Gerbillus cheesmani. They were washed in PO4 buffer solution and subsequently fixed overnight in 2.5% glutaraldehyde in 0.1 M cacodylate buffer. Following fixation, the specimens were washed 3 times in buffer and sonically cleaned for 30 seconds to remove debris adhering on the body wall of the nematode.
Microdensitometer—computer correlation analysis of ultrastructural periodicity
Authors: Ensor D.R. , Jensen C.G. , Fillery J.A. , Baker R.J.K. 
Published: June 2020

Because periodicity is a major indicator of structural organisation numerous methods have been devised to demonstrate periodicity masked by background “noise” in the electron microscope image (e.g. photographic image reinforcement, Markham et al, 1964; optical diffraction techniques, Horne, 1977; McIntosh,1974). Computer correlation analysis of a densitometer tracing provides another means of minimising "noise". The correlation process uncovers periodic information by cancelling random elements. The technique is easily executed, the results are readily interpreted and the computer removes tedium, lends accuracy and assists in impartiality.A scanning densitometer was adapted to allow computer control of the scan and to give direct computer storage of the data. A photographic transparency of the image to be scanned is mounted on a stage coupled directly to an accurate screw thread driven by a stepping motor. The stage is moved so that the fixed beam of the densitometer (which is directed normal to the transparency) traces a straight line along the structure of interest in the image.
Multivariate analysis of phenyl mercuric acetate effects on aureobasidium pullulans ultrastructure
Authors: Crang R.E. , Loesch A.J. , Pechak D.G. 
Published: June 2020

The effects of the inhibitory agent phenyl mercuric acetate (PMA) on the paint defacing fungus Aureobasidium pullulans have recently been reported using descriptive ultrastructure. We now report analyses of electron micrographs from a related study employing absolute volume determinations of whole cells and subcellular components of A. pullulans to which multivariate statistical analyses have been applied. Multivariate analysis was used to determine which subcellular components contributed most to differences between untreated and PMA treated cells, and to show relationships among those components.Cultures of A. pullulans were grown in defined media for 48 hr at 28 C from washed blastospore inocula. Additional cultures were grown in identical media supplemented with threshold inhibitory levels of PMA (5x10-7 M). Conventional specimen preparation was used to obtain randomly oriented cell sections for examination with transmission electron microscopy. Cells treated with PMA showed dense surface membranes, a loss of microfilaments and lipid inclusions, and altered mitochondrial and nuclear envelope membrane organization compared with untreated cells (Figs. 1, 2).
Computer analysis of cell ultrastructure
Authors: Timms B. G. , Wilson D.W. 
Published: June 2020

In animal tissues, the characteristic appearance of different cell types enables histologists and electron microscopists to identify a particular tissue. Uniformity of cell structure represents a dynamic morphological equilibrium dependent on the influences of cellular metabolism, the extracellular milieu and tissue specific messages from the nucleus. Using stereological techniques. Loud (1968) has demonstrated that these structural equilibria exist in normal rat liver parenchymal cells. Although stereology is widely used to provide a numerical description of the geometrical properties of cells and organelles (Weibel & Bolender, 1973), little attention has been given to devising a comparable scheme for qualitative aspects of morphology.This report concerns the development of an –Identicel— reference library of pictorial representations used to categorise the salient features of different organelles with respect to their morphological variation. An important feature of this development has been the optimisation of the number and type of descriptive elements which would, in our opinion, provide useful information.
Immunoenzymatic demonstration of the simultaneous presence of transferrin, hemopexin and albumin in a same hepatocyte and their ultrastructural localization
Authors: Kraemer M. , Foucrier J. , Vassy J. , Chalumeau M.T. 
Published: June 2020

Some authors using immunofluorescent techniques had already suggested that some hepatocytes are able to synthetize several plasma proteins. In vitro studies on normal cells or on cells issued of murine hepatomas raise the same conclusion. These works could be indications of an hepatocyte functionnal non-specialization, meanwhile the authors never give direct topographic proofs suitable with this hypothesis.The use of immunoenzymatic techniques after obtention of monospecific antisera had seemed to us useful to bring forward a better knowledge of this problem. We have studied three carrier proteins (transferrin = Tf, hemopexin = Hx, albumin = Alb) operating at different levels in iron metabolism by demonstrating and localizing the adult rat hepatocytes involved in their synthesis.Immunological, histological and ultrastructural methods have been described in a previous work.
Visualization of thermally denatured nucleosomes
Authors: Poon N. H. , Seligy V. L. 
Published: June 2020

Electron images of biological specimens composed of periodic structures are generally spurious. The reason is that unit structures may superimpose along the direction of view, and a “see through” image is formed especially from negatively stained and unstained objects. Methods to detail features of such objects from two dimensional images included optical and computer processing or combination of optical Fourier transformation and filtering. However, rotational superimposition may be employed when objects have simple symmetry.We described here the use of stroboscope illumination photography (stroboscopy) to demonstrate the distribution of globular units along nucleoprotein fibers of thermally denatured mononucleosomes. The information was further used to predict the structure of intact nucleosomes as seen from bright field (BF) and dark field (DF) electron micrographs.We previously obtained coSnsitometric scans from high resolution DF electron micrographs of partially relaxed unstained nucleosomes isolated from nuclease (EC. 3.1.4.7) digested goose erythrocyte nuclei and showed the presence of high density, periodic, contiguous globular regions (3-4 nm) along the DMA moiety.
Ultrastructural localization of specific nucleoprotein fractions
Authors: Brown G. L. 
Published: June 2020

Bismuth (Bi) stains nucleoproteins (NPs) by interacting with available amino and primary phosphate groups. These two staining mechanisms are distinguishable by glutaraldehyde crosslinking (Fig. 1,2).Isolated mouse liver nuclei, extracted with salt and acid solutions, fixed in either formaldehyde (form.) or gl utaraldehyde (glut.) and stained with Bi, were viewed to determine the effect of the extractions on Bi stainina. Solubilized NPs were analyzed by SDS-polyacrylamide gel electrophoresis.Extraction with 0.14 M salt does not change the Bi staining characteristics (Fig. 3). 0.34 M salt reduces nucleolar (Nu) staining but has no effect on interchromatinic (IC) staining (Fig. 4). Proteins responsible for Nu and glut.- insensitive IC staining are removed when nuclei are extracted with 0.6 M salt (Fig. 5, 6). Low salt and acid extraction prevents Bi-Nu staining but has no effect on IC staining (Fig. 7). When nuclei are extracted with 0.6 M salt followed by low salt and acid, all Bi-staining components are removed (Fig. 8).
The structure of the tubulin heterodimer in zinc-induced sheets
Authors: Baker Timothy S. , Amos Linda A. 
Published: June 2020

The structure of negatively stained zinc-induced tubulin sheets has been studied in projection by minimum beam microscopy and image processing. Figure (a) shows a typical sheet image, displaying the characteristic and prominent protofilament structure. The bar represents 500 nm. Figure (b) is an enlargement of part of (a).Optical diffraction patterns (Figure c) reveal an orthogonal unit cell lattice of about 9.7 nm X 8.2 nm. The 8.2 nm repeat arises from the arrangement of heterodimers in the protofilaments, and is the first observation of such a repeat in sheet aggregates. It is only observed consistently in diffraction patterns from images recorded by minimum beam methods (1,000-2,000 e/nm2) and arises from small, but reproducible, structural differences between two similar subunits believed to represent the two chemical species of tubulin monomer (55,000 M.W.). At higher electron doses (10,000-20,000 e/nm2), the additional information is lost or very much reduced, and only a repeat of 4.1 nm is observed, owing to the loss of distinction between adjacent monomers in the protofilaments.
Studies on a ph related zone phenomenon in erythrocytes
Authors: Timme Alan H. 
Published: June 2020

In 1967 Baker reported the occurrence of a zone of dense material adjacent to the inner leaflet of the unit membrane of erythrocytes exposed to buffers with a pH 4.5. It was postulated that this arose because the haemoglobin, positively charged at that pH, was attracted to the negatively charged membrane.In an attempt to elucidate the mechanisms underlying the formation of the zone, fresh human erythrocytes were washed for 15 minutes at room temperature in citrate phosphate buffers in which the pH ranged from 4.0 - 7.4, or in a standard preservative solution, Acid Citrate Dextrose (ACD), pH 5.0. Paired samples were subsequently washed in buffer at pH 7.4 for 10 minutes to assess the possible reversibility of any changes produced. The cells were fixed in 2.5% glutaraldehyde in 0.1 m cacodylate buffer at the same pH as the washing buffer for one hour and then processed in two ways: Some were post-fixed in OSO4, The cells were stained with 0.5 - 1% Alcian Blue 8 G S in cacodylate buffer pH 7.0 for 15 - 30 minutes.