bluuebunny/crossref_metadata_2025_split huggingface dataset:
InP sample preparation for the TEM by photochemical etching, ion milling, and chemical thinning
Authors: Lowes Theodore D. , Cassidy Daniel T. 
Published: February 2005

AbstractPhotochemical etching (PCE) as a method for preparation of InP semiconductor plan view samples for the transmission electron microscope is demonstrated and compared to the methods of ion milling and chemical thinning. PCE can produce small area samples for TEM analysis quickly and accurately. Also, the resulting thin regions are surrounded by a built‐in stabilizing structure that improves handleability and reduces the occurrence of handling induced fracture. © 1992 Wiley‐Liss, Inc.
Dynamics of golgi impregnation in neurons
Authors: Špaček Josef 
Published: February 2005

AbstractThis paper describes the early stages of impregnation by the Golgi rapid method in sections and blocks of brain tissue. Aldehyde‐fixed and potassium dichromate–treated sections of cerebral cortex were placed on glass slides and coverslipped. The dichromate solution was then replaced by a silver nitrate solution, and events taking place in the section were monitored and time‐lapse recorded until the impregnation was interrupted and the sections subsequently prepared for electron microscopy. The tissue blocks, fixed and chromated in the same way, were placed into a silver nitrate solution for 30 min to 24 h and the progress of impregnation compared with the results obtained in the sections on the glass slides.Two basic modes of impregnation were observed, apparently in direct relation to the process of crystallization of silver chromate: crystals of silver chromate growing directly from the surface of the tissue into the nerve cell via its transected plasma membranes, and microcrystalline precipitate of silver chromate spreading into the nerve cell from nucleation centres dispersed in the tissue. The precipitate grows inside the cell as in a preformed channel until the cell has been filled. If the nucleation begins extracellularly, the precipitate extends into the narrow intercellular gaps. Electron microscopy showed that the crystalline precipitate consisted of multilamellar formations containing dense coalesced granules that did not cross plasma or endocellular membrane boundaries. © 1992 Wiley‐Liss, Inc.
Techniques for converting golgi precipitate in CNS neurons into stable electron microscopic markers
Authors: Wouterlood Floris G. 
Published: February 2005

AbstractDirect electron microscopy of nervous tissue stained with the Golgi impregnation method is unsatisfactory because the cytoplasm of the cell bodies and processes of the impregnated neurons are completely filled with a compact precipitate of electron dense silver chromate. This precipitate entirely obscures the cytological details of the impregnated neurons. Because of its solidity and instability in aqueous solutions, the silver chromate is also a source of inconvenience during the preparation of the ultrathin sections.This review summarizes methods that have been developed with the aim of replacing the Golgi precipitate in CNS neurons with a more convenient electron dense material—for example, heavy metal salts or metallic particles. Conversion of the precipitate into a stable electron dense marker is done before the material is embedded for electron microscopy. The methods include lead, gold, and bromide substitution, treatment with ammonia, direct chemical reduction into metallic silver, and photoreduction of the silver chromate into silver through irradiation with ultraviolet light. © 1992 Wiley‐Liss, Inc.
Determining the neuronal connectivity of Golgi‐impregnated neurons: Ultrastructural assessment of functional aspects
Authors: Benshalom Gadi 
Published: February 2005

AbstractThe combined light and electron microscopic analysis of Golgi‐impregnated neural tissue is a potent tool for determining the connectivity of neural networks within the brain. In the experimental paradigms commonly applied in these studies, the Golgi‐impregnated neurons are typically examined as the postsynaptic neuronal components. The structural characteristics and the pattern of distribution of their synaptic connections with other groups of identified neurons are analyzed. Due to the high power of resolution of the Golgi‐electron microscopic technique, the ultrastructural analysis of Golgi‐impregnated neurons can be expanded to elucidate activity‐dependent structural alterations in their cytoarchitecture. These structural alterations can then be correlated under different physiological conditions with changes in the functional efficacy of the subcellular neuronal components. © 1992 Wiley‐Liss, Inc.
Identification of synaptic interactions of intracellularly injected neurons in fixed brain slices by means of dual‐label electron microscopy
Authors: Meredith Gloria E. , Wouterlood Floris G. 
Published: February 2005

AbstractThe injection of the dye Lucifer Yellow (LY) into neurons in slices of fixed brain is used to associate cells displaying a particular dendritic geometry with a specific pattern of neuronal connectivity. In the present report we expand on this technique by combining it at the electron microscopic level with immunocytochemistry and/or degeneration for the study of synaptic relationships. As a model we use the projection neurons of nucleus accumbens. These neurons were retrogradely labeled in vivo with injections or a fluorescent tracer. Fast Blue, into the ventral mesencephalon. Using epifluorescent monitoring, these neurons were located in perfusion‐fixed brain slices and intracellularly injected with LY. They were visualized in the light and electron microscope using a peroxidase‐antiperoxidase immunocytochemical method. Certain afferent connections of these neurons were identified in the same tissue through the use of either dual‐label immunocytochemistry or anterograde degeneration combined with a single‐label immunoreaction. In the dual‐label procedure, a silver‐gold intensification of the diaminobenzidine (DAB) reaction product for the first antigen (LY) was contrasted with a nonintensified reaction product for the second antigen (tyrosine hydroxylase [TH]). Ultrastructurally, metallic gold particles appeared to be dispersed over the immunolabeled perikarya, dendrites, and, occasionally, axonal terminals of LY‐injected neurons whereas the flocculent DAB reaction product was present in TH‐containing axons and terminals. Following lesions of the ventral subiculum in the hippocampal formation, degenerating axon terminals were detected in nucleus accumbens along with immunoreacted, LY‐injected neurons. The techniques outlined in this report should prove invaluable for the study of the synaptic interactions of identified neurons. They can be reliably reproduced with a high yield per experiment. © 1993 Wiley‐Liss, Inc.
Morphological study of the effects of intranasal zinc sulfate irrigation on the mouse olfactory epithelium and olfactory bulb
Authors: Burd Gail D. 
Published: February 2005

AbstractThe effects of intranasal zinc sulfate (ZnSO4) irrigation on the morphology of the olfactory epithelium and olfactory bulb were studied in mice with short survival times (as early as 1 day) and with long survival times (up to 593 days) after the irrigation procedure. As in several previous studies, the olfactory epithelium was completely destroyed within a few days after the ZnSO4 treatment. Within 2–4 days, the septum and turbinates were covered by a new, cuboidal epithelium, the cells of which differed significantly from any cells normally seen in the olfactory epithelium. Slowly, over several months, small areas of the olfactory epithelium regenerated in many of the animals.The ultrastructural changes occurring in the olfactory bulb from 1 to 25 days (the reactive stage) were characterized by degenerating olfactory axons and axon terminals, hypertrophy of astroglial cell processes, and proliferation of or extravasation by phagocytic cells. By 25 days after intranasal ZnSO4 irrigation, the number of reactive glial processes and phagocytic cells returned to normal. In some mice with survival times of 150 days or longer, there was reinnervation of small areas of the olfactory bulb by regenerated olfactory axons. These new olfactory axons innervated only superficial glomeruli or the outer portions of deeper glomeruli, but they formed synaptic contacts with mitral/tufted cells and periglomerular cells that did not differ from control animals. These findings were supported by tract‐tracing experiments with 3H‐amino acids and by behavioral analysis.In summary, the ultrastructural changes observed in the olfactory bulb in this study were not significantly different from those observed after surgical lesions of the olfactory epithelium or nerve. The olfactory bulb, however, never fully recovered; glomeruli remained shrunken (though with normal dendro‐dendritic synaptic connections), and there was minimal olfactory axon reinnervation. © 1993 Wiley‐Liss, Inc.
Fine structure of transverse tubules and the sarcoplasmic reticulum at the myotendinous junction of stretched muscle fibers of the rat
Authors: Sonoda Masaki , Moriya Hideshige , Shimada Yutaka 
Published: February 2005

AbstractThe transverse (T) tubules and the sarcoplasmic reticulum (SR) at the myotendinous junction of stretched rat skeletal muscle were examined by conventional and intermediate voltage electron microscopy. Stretching induced a large cytoplasmic space devoid of myofibrils at the ends of lengthening fibers. In this space, irregularly running tubular elements were seen. They were connected both with subsarcolemmal caveolae and with T tubules traversing to the A‐I junctional level of the preexisting myofibrils. The SR was arranged at regular interverals which were narrower than those of the adult sarcomere. This orderly spacing of the SR seems to indicate that they may play some role(s) in myofibril assembly and/or T tubule arrangement. © 1993 Wiley‐Liss, Inc.
Diffraction contrast near heterostructure boundaries—its nature and its application
Authors: Bangert U. , Harvey A. J. 
Published: February 2005

AbstractTwo phenomena of diffraction contrast arising at or near III‐V compound hetero‐structure boundaries are described and quantitatively analyzed. In the first observation α/δ‐fringe contrast at boundaries inclined to the electron beam is discussed. Theoretical fringe profiles are generated according to the theory by Gevers et al. in 1964, which are then compared with experimental profiles. Applications to the characterization of AlGaAs/GaAs and InGaAsP/InP interfaces regarding composition, abruptness, and lattice tilt are presented. In the second study a new and very sensitive characterization technique for the direct determination of the strain in strainedlayer structures is described. The method uses electron microscope images of 90°‐wedges, which exhibit a shift in the thickness contours due to strain relaxation at the edge, and compares these to images which are obtained theoretically by implementing finite element strain calculations in wedges in the dynamical theory of diffraction contrast. The considerable potential of this method is demonstrated on the strain analysis of strained GaInAs/GaAs structures. © 1993 Wiley‐Liss, Inc.
An analytical electron microscopic investigation of precipitation in an Al‐Cu‐Zn‐Mg‐Ag alloy
Authors: Hasan F. , Lorimer G. W. 
Published: February 2005

AbstractThe distribution, morphology, chemistry, and crystallography of the precipitates formed during aging of an Al‐Cu‐Zn‐Mg‐Ag alloy have been studied using analytical transmission electron microscopy. The first precipitates to appear during aging at 150°C were thin hexagonal‐shaped plate‐like precipitates which formed on the {111}Al planes. These precipitates had a face‐centred orthorhombic crystal structure and their composition was essentially CuAl2 although they contained a trace of silver. At peak hardness the microstructure consisted of the plate‐like precipitates on {111}Al planes and θ′ precipitates on {100}Al planes. Overaging resulted in the precipitation of equilibrium θ, CuAl2, which exhibited a lath morphology and an orientation‐relationship with the matrix (210)Al ∥(110)γ; (001)Al misorlented from (001)γ by ∼6°. Prolonged overaging at 250°C resulted in the formation of cuboid‐shaped Al5(Cu,Zn)6Mg2 precipitates which had a cubic crystal structure and a cube:cube orientation‐relationship with the matrix. © 1993 Wiley‐Liss, Inc.
Use of freeze‐substitution and molecular distillation drying in the preparation of Dunaliella parva for ion localization studies by X‐ray microanalysis
Authors: Hajibagheri M. A. , Flowers T. J. 
Published: February 2005

AbstractThe determination of ion concentrations within cells and sub‐cellular compartments remains a difficult procedure, as the volumes to be analyzed are rather small. X‐ray microanalysis is sufficiently sensitive, and has adequate resolution, to measure these concentrations. The major difficulties are related to the preparation of material for analysis. We have compared the measurement of sodium, potassium, and chloride contents in a salt tolerant unicellular alga, Dunaliella parva, following either freeze‐substitution (using two different resins) or molecular distillation drying. All three procedures gave similar results: after freeze substitution, ion contents were marginally (but not significantly) higher following embedding in Nanoplast MUV 116 resin than in Spurr resin. Since the Nanoplast can be polymerised at low temperatures, it has advantages over the Spurr resin. © 1993 Wiley‐Liss, Inc.
Developments in three‐dimensional stereo brightfield microscopy
Authors: Willis Byron , Turner James N. , Collins Doris N. , Roysam Badrinath , Holmes Timothy J. 
Published: February 2005

AbstractWe present recent developments of a widefield computer/microscope system and image reconstruction algorithm for producing three‐dimensional (3D) increased depth of field images in the form of brightfield stereo pairs of thick specimens. The theoretical principle of this image reconstruction technique is based on Weiner‐type inverse filtering. A number of extensions and refinements to our previous work have included further testing of the system with a broader class of specimens and the implementation of several pragmatic refinements important for future 3D microscopy systems. These refinements include histogram modification routines for improving visualization, a preprocessing routine to eliminate edge artifacts due to circular convolution and other effects, stereo viewing angle optimization, a rule of thumb estimate for the axial sampling rate, and incorporation of a variation of the Fast Fourier Transform and filtering operations that significantly reduce computational time. Images of spyrogyra, neonatal rat hippocampal neurons, and cervical/vaginal cell smears are presented to show the utility of these methods for 3D visualization. The primary advantages of these methods are that they operate with an ordinary transmitted light microscope and are inexpensively implemented on a personal computer with reasonable computation time. © 1993 Wiley‐Liss, Inc.
Freeze substitution after fast‐freeze fixation in preparation for immunocytochemistry
Authors: Nicolas Marie‐Thérèse , Bassot Jean‐Marie 
Published: February 2005

AbstractAs compared to classical chemical fixation, the physical immobilization of ultrastructures by fast‐freeze fixation (FFF) and the subsequent exchange of water in its solid state by freeze substitution (FS) improve the preparation procedure for immunogold labeling (IGL).FFF‐FS results in a morphological preservation of unchallenged quality, as well as in a better preservation of antigenic reactivity, thus allowing remarkable precision of labeling on sections.However, FFF, particularly over a cooled metal plate, requires a heavy and expensive machine. It is not suitable for all biological specimens and in the best conditions, which remain difficult to standardize, the thickness of the well‐preserved portion of the specimen does not exceed a few μm for compact tissues, and exceptionally 30–40 μm for isolated cells.The FS procedure is long and must be adjusted empirically for every new specimen and antigenic detection. The preservation of a given antigen's reactivity in the presence of fixative agents and embedding resins remains unpredictable. The action of fixative agents is different and milder in FS than when they are used classically in chemical fixation. By chance, one of the best FS procedures for the preservation of both ultrastructure and antigenicity appears to be by using acetone alone, together with a molecular sieve to improve the water exchange process. A large choice of embedding resins usually allows us to find a compromise between ultrastructural and antigenic preservation. © 1993 Wiley‐Liss, Inc.
Freeze‐Substitution for morphological and immunocytochemical studies in insects
Authors: Steinbrecht Rudolf Alexander 
Published: February 2005

AbstractMethods of plunge freezing and freeze‐substitution (FS) for insect antennae and similar body appendages are described. In these more or less cylindrical specimens, usually a layer below the cuticular surface of 10–15 μm thickness is well preserved without freezing damage, further inwards ice‐crystal ghosts of increasing size are encountered, but in the very centre of antennal branches (diameter ∼80 μm) of the silkmoth, Bombyx mori, freezing damage is usually reduced again. The frost‐hardy species, Poecilocampa populi and Boreus hiemalis, exhibit regions free from freezing damage up to 40 μm below the cuticular surface. Secondary freezing damage in silkmoth sensory hairs is observed only after deliberately warming the specimens to –43°C for >>10 min before FS. Secondary artefacts due to the substitution process are investigated by comparison with freeze‐etching and by comparing different FS media and protocols. Methanol is not recommended as a substitution medium for insect specimens. Structures particularly liable to substitution damage are the stimulus‐conducting pore tubules of olfactory sensilla and the receptor cell membrane. Extraction of soluble components is more likely with pure organic solvents without added chemical fixing agents and with prolonged substitution at elevated temperatures. Such extraction may also be a possible artefact with soluble antigens in immunocytochemical studies. A review is given of the major achievements attained with these techniques in insect functional morphology and immunocytochemistry. © 1993 Wiley‐Liss, Inc.
The use of in situ hybridization to study erythropoietin gene expression in murine kidney and liver
Authors: Koury Stephen T. , Bondurant Maurice C. , Semenza Gregg L. , Koury Mark J. 
Published: February 2005

AbstractIn situ hybridization has been used to localize erythropoietin (EPO)‐producing cells in murine kidney and liver. Peritubular interstitial cells were the only cell type that produced EPO in the kidney. The EPO‐producing cells were primarily concentrated in the inner cortex but were also seen in the outer medulla and outer cortex. EPO‐producing cells represented less than 10% of the total interstitial cell population. The number of EPO‐producing cells per square centimeter of cortex directly correlated with the amount of renal EPO mRNA and varied in an inverse exponential manner with hematocrit. These results suggest that EPO is expressed in an all‐or‐none fashion in peritubular interstitial cells and that the oxygen carrying capacity of blood is the major regulator of renal EPO production. Peritubular interstitial cells were also identified as the renal source of human EPO in transgenic mice that expressed human EPO mRNA in a regulated fashion in the kidney. Transgenic mice exhibiting inducible supranormal liver expression of human EPO were used to identify EPO‐producing cells in the liver. Hepatocytes surrounding central veins produced human EPO in these mice. Individual hepatocytes were able to modulate their production of human EPO depending upon the severity of anemia to which they were subjected. Two types of widely scattered cells produced EPO in severely anemic nontransgenic mice. Eighty percent of EPO‐producing cells were hepatocytes and 20% were classified as being nonepithelial based on their nuclear morphology and location in venous sinusoids. © 1993 Wiley‐Liss, Inc.
Hormonal influence on ionic channels in myometrium
Authors: Ludmir Jack , Erulkar Solomon D. 
Published: February 2005

AbstractSmooth muscle cells in culture isolated from myometrium were characterized by scanning microscope and immunohistochemistry. Using the whole‐cell patch‐clamp configuration, and the single channel bilayer technique, the properties of ionic channels expressed in both non‐pregnant and pregnant myometrium have been described. The predominantly expressed potassium channel changes from a transient inactivating outward current seen before puberty, to a calcium sensitive delayed outward current present in the adult stage. A change in the calcium channel population occurs from the nonpregnant to the pregnant state. Finally, sodium channels are expressed with greater frequency towards the end of gestation suggesting that these channels may play a role in labor. © 1993 Wiley‐Liss, Inc.
Rapid primary microwave‐glutaraldehyde fixation preserves the plasma membrane and intracellular structures of the protozoan Tritrichomonas foetus
Authors: Benchimol Marlene , Goncalves NoéMia Rodrigues , de Souza Wanderley 
Published: February 2005

AbstractTritrichomonas foetus, a pathogenic protozoan, was used as a model to analyse microwave‐stimulated fixation as a procedure of preparation of biological samples for electron microscopy of thin sections and freeze‐fracture replicas. Good preservation of the protozoan structure was achieved by microwave‐stimulated fixation and Epon polymerization. The membrane structure, as visualized in freeze‐fracture replicas, was well preserved. © 1993 Wiley‐Liss, Inc.
Selective etching of ALAs for preparation of III–V semiconductor thin foils
Authors: Breen Kathleen R. , Wilson R. A. , McClintock J. A. , Ahearn J. S. 
Published: February 2005

AbstractA new method of thin section preparation of III–‐V semiconductors and multilayers for transmission electron microscopy (TEM) is presented that exhibits considerable advantages over conventional methods such as ion beam milling and jet thinning. GaAs thin films and multilayers of GaAs/InxGa1‐xAs/GaAs are grown over an etch release layer of AlAs on GaAs substrates by molecular beamepitaxy (MBE). Planar TEM sections prepared by selective etching from these samples show improved ability to image film morphology and dislocation arrangements, and the resulting large thin electron transparent areas facilitate dislocation density measurements and detection of spatial variations. Avoidance of radiation effects and wedge shaping, both common to ion milled samples, allows this method to be used to prepare uniform thickness standards of single layer GaAs films for EDS analysis or lattice imaging. © 1993 Wiley‐Liss, Inc.