bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extending the limit of atomic level grain boundary structure imaging using high‐resolution electron microscopy
Authors: Krakow William 
Published: February 2005

AbstractIt has been possible to image ∑ = 21/[111]21.8° tilt boundaries in thin Au films and to deduce their atomic arrangements. These results represent an electron microscopic resolution level of 1.43 Å, attainable with a small amount of image processing, which produces interpretable structure images. This substantial improvement over other recent grain boundary studies, which required about 1.9–2.0 Å resolution, clearly demonstrates that many more tilt grain boundary orientations are now accessible instead of a limited subset.
Transmission electron microscope in situ fatigue experiments: A computer‐control approach
Authors: Vecchio Kenneth S. , Hunt John A. , Williams David B. 
Published: February 2005

AbstractA computer‐control procedure was developed to facilitate in situ fatigue experiments within an intermediate voltage transmission electron microscope using a goniometer‐type straining holder. The procedure was designed to allow sine‐wave tension‐tension cyclic loading of a microfatigue specimen similar in geometry to a center‐crack panel fatigue specimen. Computer control allows greater freedom for the operator to control the experiments while providing better reproducibility from one test to another. Further development of this procedure is possible by coupling this computer‐control technique with computer‐controlled stage motion and digitized TV imaging.
Oxygen content of the fixative is important in the interpretation of the ultrastructure of ischaemic myocardium
Authors: Maxwell Linda , Gavin John Bevan , Walker Sharon 
Published: February 2005

AbstractIsolated rat hearts were subjected to 15, 45, or 60 minutes of global ischaemia and then fixed by perfusion at 37°C with glutaraldehyde containing various amounts of oxygen. This either had been bubbled with 100% oxygen (PO2 620 mm Hg) or with 100% nitrogen (PO2 40 mm Hg) immediately before use, or it had been routinely prepared and stored exposed to atmospheric oxygen (PO2 245 mm Hg). The ultrastructure of myocytes and endothelial cells subjected to 15 minutes of ischaemia was not affected by the treatment of the fixative. However, when the tissue subjected to longer periods of ischaemia was fixed with routinely prepared or oxygen‐bubbled glutaraldehyde, ultrastructural changes characteristic of reoxygenation damage were uniformly evident in both the microvasculature and myocytes. These qualitatively distinct changes included mitochondrial swelling, cell swelling, endothelial bleb formation, and narrowing of capillary lumina. These abnormalities were not observed in tissue fixed with nitrogen‐bubbled glutaraldehyde. These findings indicate that deliberate steps should be taken to reduce or eliminate dissolved oxygen from the fixatives used to study ischaemic tissues. Otherwise artefactual reoxygenation damage in vitro may occur and make valid ultrastructural interpretation difficult or impossible.
Physiology and pathophysiology of the human spermatozoon: The role of electron microscopy
Authors: Zamboni Luciano 
Published: February 2005

AbstractIn this article, the major contributions of electron microscopy to the present understanding of the physiology and pathophysiology of the human spermatozoon are reviewed. The ultrastructural organization of sperm organelles playing a significant role for cell function and, therefore, for the reproductive process is described. Also, the major abnormalities and defects of the various organellar systems and how they impair the reproductive function and/or the viability of the cell are reviewed.
Dispermic fertilization of human oocytes
Authors: van Blerkom Jonathan , Henry George 
Published: February 2005

AbstractRegardless of whether fertilization occurs in vivo or in vitro, polyspermic penetration of the human oocyte is a not infrequent cause of reproductive failure. This report describes the occurrence of human eggs fertilized by two spermatozoa and the variable developmental potentials expressed by the resultant embryos. The cellular and subcellular events that characterize the pronuclear and early cleavage stages of preimplantation embryogenesis are discussed with respect to the ability of such embryos to progress to implantation.
Versatile controlling system for cryopreparation techniques in electron microscopy
Authors: Humbel Bruno M. , Weber Klaus , Merkl Rainer 
Published: February 2005

AbstractA new setup for freeze‐substitution and a versatile controlling system has been developed. Our goal was to build a simple system allowing precise control of the physical parameters of freeze‐substitution experiments to learn more about their influences on the cellular ultrastructure and immunoreactivity of macromolecules. An improved apparatus for freeze‐substitution, based on liquid nitrogen cooling, and a universal software for controlling the complex preparation protocols from cryofixation to final polymerization are described. This controlling system has the following advantages: it allows precise control and registration of temperature profiles, reconstruction of each individual step of previous experiments, and optimization of working conditions. The setup of the freeze‐substitution apparatus is designed to run many different substitution media in parallel; freeze‐substitution (cryostat), embedding (working platform), and polymerization are carried out at separate places; therefore, more experiments can be done simultaneously. The ergonomic working platform allows exchange of media at controlled temperature and easy handling; survey of the temperature in individual tubes is possible, and the system is protected from water condensation and uncontrolled warming by the deep freezer.
Determination of vesicle size distributions by freeze‐fracture electron microscopy
Authors: Hallett F. R. , Nickel B. , Samuels C. , Krygsman P. H. 
Published: February 2005

AbstractThe most common electron microscopic technique for obtaining information on size distributions of uncollapsed membrane vesicles is based on the method of van Venetie (1980). This technique involves the sizing of only those vesicles that were freeze fractured at their equatorial planes. As a result, only a small number of images can be used to generate size distributions. Further, the technique is susceptible to systematic error. An alternate approach is to consider the complete distribution of image sizes and use this distribution to determine the average size and distribution of the vesicles. It is shown that the mean vesicle size is 4/π times the mean image size. As well, a parameter, m, which can be determined from the image distribution, can be used to characterize the vesicle distribution. The advantage of this new approach is that images of all vesicles are used, leading to a statistically better determination of vesicle sizes.
In vivo, real‐time confocal imaging
Authors: Jester James V. , Andrews Peter M. , Matthew Petroll W. , Lemp Michael A. , Dwight Cavanagh H. 
Published: February 2005

AbstractWe have adapted a tandem scanning confocal microscope for real‐time, non‐invasive imaging of cells under in vivo conditions. This form of in vivo confocal imaging relies on the optical sectioning abilities of the confocal microscope to obtain en face, sequential, reflected light images of cells at various depths, up to 1 mm, within opaque organs in living animals. Of major consideration in the design of an in vivo confocal microscope is maximizing the real‐time detection of signals reflected from low contrast structures which can be affected by the microscope design, objective, and image detector systems. Using an in vivo confocal microscope design with a 20 × BioOptics surface contact objective we have obtained live cellular images from selected tissues including cornea, kidney, liver, adrenal, thyroid, epididymis, and muscle and connective tissue of rabbits and rats. Images were captured, digitized, and processed using a DAGE Mti low light level SIT camera coupled to a Gould IP9527 image processor. In vivo images were also compared with conventional bright field light and scanning electron microscopic images of “dead,” fixed tissues. Overall, in vivo confocal imaging can provide remarkable detail of living cells comparable to that of conventional microscopic images of “dead,” fixed, and stained tissue. A more unique feature of in vivo confocal imaging is the ability to study cellular structure and function sequentially over time in the same organ or tissue and represents a fundamentally new paradigm in microscopy. With continued refinements in the microscope, objective and detection system designs and their consequent improvements in lateral and axial resolution, in vivo confocal microscopy will enable us as observers to see what no one has been able to see before.
Ultrastructural investigation of neurons identified and localized using the confocal scanning laser microscope
Authors: Deitch Jeffrey S. , Smith Karen L. , Swann John W. , Turner James N. 
Published: February 2005

AbstractStudies of labeled neurons at the light‐microscopic level often pinpoint a substructure of particular interest, i.e., a synapse or a spine. An ultrastructural investigation would explain a lot about how these structures arose, how they function, and how they are regulated. Finding a small region in a large block can require constant checking during sectioning, until past the structure. In our pursuit of the synaptic structure of varicosities on the axons of neurons identified physiologically and morphologically at the light level, we have combined confocal scanning laser microscopy (CSLM) with conventional and high‐voltage electron microscopy (EM). CSLM images were collected in the reflection mode to view neurons filled with horseradish peroxidase and stained with nickel‐intensified diaminobenzidine, which is compatible with EM. The CSLM optical sections provided a record of what one should expect to see at regular intervals throughout the depth of the tissue block. We have shown that the CSLM greatly simplified the task of localizing small structures in brain tissue prepared for EM.
Immunogold labelling of the intermediate filament‐lamina‐nuclear matrix system in hela and bhk‐21 cells
Authors: Jiao Renjie , Wu Donglan , Zhang Bo , Cai Shutao , Zhai Zhonghe 
Published: February 2005

AbstractWhole‐mount, sequentially extracted cells combined with immunogold electron microscopy were developed to demonstrate the intermediate filaments, lamina, and nuclear matrix (IF‐L‐NM) and to identify their protein components. The IFs of HeLa cells were reacted both with keratin and vimentin monoclonal antibodies; meanwhile, the IF network of BHK‐21 cell was reacted only with vimentin monoclonal antibody. The lamina and nuclear matrices of both HeLa and BHK‐21 cell were labelled, respectively, with lamin monoclonal antibody‐gold complex and 280 Kd nuclear matrix protein monoclonal antibody‐gold complex. The monoclonal antibody to keratin could cross‐react with the lamina both of HeLa and BHK‐21 cells.
Cellular location of thymus‐leukemia (TL) antigen as shown by immuno‐cryoultramicrotomy
Authors: Hartfield Cheryl , McDowall Alasdair , Loveland Bruce , Lindahl Kirsten Fischer 
Published: February 2005

AbstractThymus‐leukemia (TL) antigen is a class I molecule of the major histocompatibility complex that is expressed on the surface of mouse cortical thymocytes. Though not expected, it has been reported that TL antigen can be found on isolated mitochondria of TL+ cells. We used immuno‐cryoultramicrotomy to look for TL on mitochondria in situ, thereby avoiding the plasma membrane contamination that occurs when isolating organelles. Establishing optimal fixation conditions was crucial, as mitochondrial structure was not preserved by the low concentrations of fixative needed for detection of antibody labeling. The plasma membranes of tissue culture and thymus cells were labeled well with anti‐TL antibody and protein A‐gold conjugate, while mitochondria within the cells were not labeled. Isolation of mitochondria on a one‐step Ficoll gradient resulted in a purer organelle preparation than did isolation of mitochondria by centrifugation alone. Generally, mitochondria within this purer preparation were not labeled. Our data show that under conditions where contamination by plasma membrane is not a major concern, TL antigen cannot be detected on mitochondria.
Immunoelectron localization of mitochondrial F1 factor in cryosections of heart muscle cells
Authors: Real Suzana Corte , de Meirelles Maria de Nazareth Leal 
Published: February 2005

AbstractImmunocytochemistry was used to investigate the localization of F1 ATPase in mitochondria of cryosections of adult mouse heart muscle cells. The initial aldehyde fixation was the only denaturation step for antigens. The fine structure was preserved with contrast enhancement as the sections were maintained hydrated, with the advantage that the entire procedure is completed in one working day. The reaction was highly specific, and entire mitochondria were labeled with the Protein A‐gold complex. A new analytical technique, electron spectroscopic imaging (ESI), contributed to a better visualization of the localization of the F1 factor.
Ultrastructural localization of gold particles within neural grafts labeled with gold‐filled sendai viral envelopes
Authors: Kott Jon N. , Westrum Lesnick E. , Ardizzoni Susan C. , Arendash Gary W. 
Published: February 2005

AbstractThe ability to discriminate between host and donor cells is required to interpret the organization of neural grafts at the electron microscopic (EM) level. Using light microscopy, Ardizzoni et al. (Ardizzoni, S.C., Michaels A., and Arendash, G.W. [1988] Science 239: 635–637) described a method, using gold‐filled Sendai viral envelopes, for labeling cell suspensions prior to grafting. As the colloidal gold used in this procedure is especially attractive for use with EM, we have examined the ultrastructural distribution and character of this label with transplanted cells. Cell suspensions taken from the nucleus basalis of fetal rats were labeled using gold‐filled Sendai viral envelopes and grafted into the dorsal neocortex of adult host rats with nucleus basalis lesions. After varying survival times ranging from 1 to 14 months, grafts and surrounding host tissue were examined using standard EM techniques. Within the graft site, gold particles ranging from 10–200 nm were found associated with various membranes throughout the cytoplasm of both neurons and glia. Gold particles of similar size were also found within the nuclei of neuronal and non‐neuronal cells. Host cells near the graft site contained some small gold particles (10–40 nm). Control injections of non‐viable, gold‐labeled cells or colloidal gold alone resulted in similar patterns of small gold particles which were readily discriminable from the larger virally inserted gold particles found in viable labeled donor cells. We conclude that this method allows discrimination between closely associated host and donor cells.
A study of protein A‐gold resolution for immunoelectron microscopy
Authors: Shida Hisato 
Published: February 2005

AbstractFor the purpose of investigating a topographical correlation between antigen molecules and protein A‐gold(PAG) particles which localized as an immunocytochemical probe, the simplest model on a localization pattern of antigen molecules, which were arranged two‐dimensionally on a plane surface of the resin, was used. Ultrathin sections of a G‐actin layer, which was adsorbed on epoxy resin and was re‐embedded subsequently in JB‐4 resin, was stained indirectly with rabbit anti‐actin antibody and subsequently by PAG. From this immunoelectron microscopy, a histogram (relative frequency, denoted by y vs. relative length, denoted by x) was obtained using a computer‐assisted method. For this histogram, a fitting curve was calculated by a least squares optimization and three parameters (H, U, and W) of the curve which could be useful for a study on the topographical organization of antigen molecules were estimated. Parameter H (maximum y of the curve) would reflect the maximum amount of epitopes at x = U. Half width W, which is the width of the curve at y = H/2, would reflect a breath of epitope masses. This fitting curve was separated into two overlapping curves whose Ws were different from each other. The one constituent curve of which value W was smaller than the other was regarded as a unit curve and the other constituent curve could be resolved into many unit curves whose W values are the same. From these unit curves, the resolution power of the immunoelectron microscopy, using a post‐embedding procedure of ultrathin sections, was estimated as 58–66 A°.
Similar features in Z bands of both skeletal and cardiac muscle revealed by image enhancement
Authors: Schroeter John P. , Bretaudiere J. P. , Goldstein Margaret A. 
Published: February 2005

AbstractWe have shown previously that the small square (ss) and basket weave (bw) states of the Z band lattice in cardiac and skeletal muscle are related to the contractile state of the muscle. We have used two‐dimensional image processing techniques on digitized electron micrographs to enhance the structural features of each projected lattice form in cardiac and skeletal muscle. Four different processing techniques were employed to assess the effect of enhancement artifacts on the resulting Z band images.We observed only slight differences between enhanced images of a particular Z band form produced by the four different techniques. Every enhanced image showed an approximate four‐fold symmetry independent of muscle type or Z band lattice form. Each enhanced image showed four cross‐connecting Z‐filaments which appeared to connect each axial filament to the four nearest axial filaments. In bw images from both cardiac and skeletal muscle, axial filaments had a greater apparent diameter and a greater interaxial filament spacing than in the ss images. In both muscle types, the cross‐connecting Z‐filaments appeared to overlap half‐way between axial filaments in the ss images while the bw images showed no such overlap. These structural features are consistent with a dynamic Z band lattice that participates in muscle contraction.
A technique for the preparation of cross‐sectional TEM samples of ZnSe/GaAs heterostructures which eliminates process‐induced defects
Authors: Yu J. E. , Jones K. S. , Park R. M. 
Published: February 2005

AbstractCross‐sectional transmission electron microscopy (TEM) sample preparation of ZnSe/GaAs epitaxial films is investigated. Conventional argon ion milling is shown to produce a high density (∼ 5–8 × 1011/cm2) of small (diameter ∼ 60–80 Å) extended defects (stacking faults, microtwins, double positioning twins, etc.). In addition, transmission electron diffraction results indicate a thin ZnO layer can also occasionally form upon ion milling or electron‐beam irradiation although the exact conditions for ZnO formation are not well understood. Conventional TEM (amplitude contrast) and high‐resolution TEM (phase contrast) imaging in combination with transmission electron diffraction studies were performed to determine the optimum method of removing the ion milling related damage and ZnO layers during sample preparation. HF/HCl, NaOH/H2O, H2SO4/H2O2/H2O and Br2/CH3OH etching mixtures as well as low voltage argon or iodine ion milling were studied. A low energy (2 ke V) iodine or argon ion milling step was shown to remove the ZnO layer and reduced the density of the extended defects associated with Ar+ ion milling, but was unsuccessful in removing all of the defects. Auger electron spectroscopy results indicate residual iodine was either left on the surface or implanted beneath the surface during iodine ion milling. Etching the XTEM samples in HF/HCl was shown to be effective in removing the ZnO layer but had little or no effect on the ion milling induced defects. Etching the samples in a 0.5% Br2/CH3OH solution resulted in complete elimination of the ion milling induced extended defects including the residual defects associated with iodine ion milling. In addition the Br2/CH3OH etch produced the best surface morphology. Thus a brief (1–2 seconds) Br2/CH3OH etch after conventional preparation (argon ion milling) of cross‐sectional ZnSe/GaAs TEM samples appears to be an inexpensive and superior alternative to iodine ion milling.
Simple method for the preparation of inp based samples for TEM investigation
Authors: Barna Árpád , Pécz Béla 
Published: February 2005

AbstractA novel, rapid, and simple method is described for the preparation of InP based samples for investigation by transmission electron microscopy (TEM). The key feature of the technique is Ar+ ion bombardment in an iodine ambient. Cross sectional micrographs of Au/InP samples are shown as an example. The technique developed produces a large area of transparent region.
Fetal development and regulation of pituitary cell types
Authors: Dubois Paul M. , Hemming Fiona J. 
Published: February 2005

AbstractThe ontogenesis of the pituitary gland is considered from anatomical and functional points of view. Embryogenesis of the hypothalamo‐pituitary unit involving development of the hypothalamo‐hypophyseal portal system is complete during early life as shown in several mammalian species. The ultrastructural characteristics of the different cell types during development are described according to observations made by using immunochemical techniques. The patterns of differentiation of the cell types are reviewed according to studies of pituitary glands from human anencephalic fetuses and encephalectomized rat fetuses as well as in vitro studies of cultured pituitary primordia in synthetic media. The maturation of the neuroendocrine mechanisms controlling the secretion of fetal hormones is also analyzed. During fetal life, the factors implicated in the regulation of pituitary hormone secretion are generally the same as in adults, but the intensity of the response of pituitary cells to their action is variable according to the species, thus reflecting an immaturity in the functioning of certain cell types.
Application of preembedding immunohistochemistry in the study of adenohypophysial plurihormonality
Authors: Osamura R. Yoshiyuki 
Published: February 2005

AbstractAn immunoelectron microscopy preembedding technique has been utilized as a method which enables the observation of various bioactive substances in various intracellular organelles. In this review article, the observations made by preembedding immunoelectron microscopy describe plurihormonal pituitary cells emphasizing subcellular localization of hormones and their alterations.