bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of aqueous standards for low temperature x‐ray microanalysis
Authors: Reid A. P. , Potts W. T. W. , Oates K. , Mulvaney R. , Wolff E. W.
Published: February 2005

A technique, using Nuclepore polycarbonate membrane filters as a containing medium for very small volumes of ionic standard solutions, to produce homogeneous ice standards is described. The standards are suitable for use in a scanning electron microscope. The relationship between elemental X‐ray counts and ionic concentration is found to be linear. The method is rapid and simple. Minimum detectable concentrations are given. © 1992 Wiley‐Liss, Inc.
Ultrastructural studies on membrane, cytoskeletal, mucous, and protective compartments in olfaction
Authors: Ph. M. Menco Bert
Published: February 2005

There is a great variety in the morphological appearance of olfactory structures across the metazoan animal kingdom. Despite this variety the receptive structures themselves have a strikingly similar architecture, namely some type of elongated cellular extension that is spanned by a membrane and surrounded by mucus. These cellular extensions can either be modified primary or secondary cilia, or microvilli. There are more similarities between membranes of these extensions than between the cytoskeletal elements immediately underneath the membranes. One might infer that the cytoskeletal elements of the cellular extensions merely serve as a scaffold for the membranes, whereas the similarity in membrane ultrastructure provides morphological evidence supporting the concept that these membranes are responsible for the initial olfactory transduction process. The transduced message is transported to the brain, where it is decoded to initiate the cascade of events resulting in the organisms' appropriate behavioral response to the initial odorous stimulus. The varying appearance of olfactory structures across the animal kingdom is probably produced by evolutionary pressure to adapt the olfactory system to the animal's environment. This review deals with the ultrastructural aspects of these facets of olfaction. © 1992 Wiley‐Liss, Inc.
Peripheral sensilla of some lower invertebrates: The platyhelminthes and nematoda
Authors: Wright Kenneth A.
Published: February 2005

The flatworms (Platyhelminthes) and the round worms (Nematoda) are phylexhibiting strikingly different levels of cellular organization. In both, sensilla are composed of the endings of sensory dendrites intercalated into their epidermis.

In flatworms, sensilla that penetrate the syncytial epidermis bear sensory processes derived from cilia. In free‐living species, the sensory processes more closely resemble motile cilia, while in parasites, greater deviations occur from the classical cilium pattern. Estimates of the function of the various sensilla have been largely arbitrary, and remain based on ultrastructural features.

Sensilla in round worms lie below or within a heavy secreted cuticle. Two glia‐like cell types occur. The socket cell mediates contact with cuticle and is responsible for cuticular modifications essential for operation of the sensillum. The sheath cell forms a receptor cavity around the sensory processes and regulates its environment. Sensory processes vary greatly from the classical cilium pattern. Absence of a basal body, but preservation of a ciliary necklace, suggests that the latter has a primary importance in sensory transduction. Estimates of function are based largely on ultrastructural features and analogies to arthropod sensilla. Genetic studies with the free‐living nematode Caenorhabditis are beginning to demonstrate details of function and development.

Speculations on the roles of basal bodies, rootlets, and vesicles and on the significance of recessed sensilla are given. © 1992 Wiley‐Liss, Inc.
Preparation of TEM foils from Nb‐10 a/ Si
Authors: Cockeram Brian , Omlor Ralph E. , Srinivasan Raghavan , Weiss Isaac , Jackson Allen G.
Published: February 2005

Ductile phase toughened composites contain phases with significantly different physical properties. Consequently, these phases thin at different rates depending on the sample preparation procedure. A new TEM foil preparation method for the ductile phase toughened Nb‐10 a/o Si material has been developed. The method involves chemical thinning in a 70% nitric acid/ 30% hydrofluoric acid solution followed by electropolishing in a 12.5% sulfuric acid/87.5% methanol electrolyte at −40°C. This procedure for making TEM foils results in large thin areas with the minimum of artifacts. Mechanical grinding of a sample followed by either ion milling, dimpling, or electropolishing produced foils with large electron transparent areas, but with uncharacteristic features of the original Nb‐10 a/o Si alloy microstructure. These artifacts were identified as dislocations, surface mottling, and antiphase domains. © 1992 Wiley‐Liss, Inc.
In situ freeze‐fracture of monolayer cell cultures grown on a permeable support
Authors: Todd John H. , Sens Donald A. , Sens Mary Ann , Hazen‐Martin Debra
Published: February 2005

The growth of cultured epithelial cells on permeable supports allows increased cell differentiation and the assessment of a variety of transcellular and paracellular transport processes. The need to assess the corresponding ultrastructural characteristics of these cells underidentical conditions prompted this laboratory to develop a reliable method for producing freezefracture replicas of these cultures. Sections of filter inserts with the cell‐side facing up are placed between layers of polyvinyl alcohol with a strip of mylar positioned on the upper layer of polyvinyl alcohol. Following freezing, the monolayer is fractured by lifting the mylar strip from the assembly. The result is a consistent fracture of the apical membrane sufficient for analysis of tight junction sealing strands, microvilli distribution, and intramembranous particle (IMP) distribution between apical and lateral membrane domains. This method utilizes standard equipment and readily available materials and, most importantly, allows the freeze‐fracture and replication of an undisturbed cell monolayer. © 1992 Wiley‐Liss, Inc.
Experimental morphology of insect olfaction: Tracer studies, x‐ray microanalysis, autoradiography, and immunocytochemistry with silkmoth antennae
Authors: Steinbrecht Rudolf Alexander
Published: February 2005

The general morphology and methodological peculiarities of insect sensilla are briefly reviewed. The stimulus conducting pore‐tubule systems of pheromone‐sensitive sensilla of the silkmoths Bombyx mori and Antheraea polyphemus are described. Lipophilic tracers readily enter the hair lumen, while hydrophilic tracers do so only after prolonged extraction with lipid solvents and/or pronase. X‐ray microanalysis demonstrates a high potassium content of the sensillum lymph; calcium was only found in the haemolymph above detection limit. Auxiliary cells rapidly take up radioactive leucine administered via the haemolymph. Antibodies against pheromone‐binding protein of Antheraea polyphemus label the sensillum lymph of sensilla trichodea, but not of sensilla basiconica in A. polyphemus as well as in B. mori. The cytoplasm of auxiliary cells of the sensilla trichodea is also labelled. The results are discussed in context with present hypotheses on the role of sensillum lymph in stimulus transport and inactivation. © 1992 Wiley‐Liss, Inc.
Limitations of monastral blue as a vascular label: Rapid rate of clearance is age‐dependent, and interactions with anesthetics depress arterial blood pressure in rats
Authors: Drake Wendy T. , Creighan Michael , Sims David E.
Published: February 2005

Monastral blue (MB) has been described as an inexpensive, nontoxic vascular label. Discrepancies as to its rate of removal from circulation and physiological side effects prompted this study in which retention time of MB in the vascular system and effects of MB upon arterial blood pressure with different anesthetics (halothane, isoflurane, and pentobarbital) were measured in rats. Arterial pressure was monitored during intravenous infusion of MB with or without Evans blue, an albumin label. Localized areas of leakage were created by injecting 30 μL of 10−4 M histamine into abdominal dermis at −2, 0, 5, 7, 10, and 15 minutes from infusion of MB. Mean arterial pressure decreased by 25–30% after MB infusion when halothane or isoflurane was used, but not with pentobarbital. Sites which leaked at 10 and 15 minutes did not usefully label with MB, although Evans blue‐labelled albumin appeared in the interstitium. Younger, lighter rats (125–200 vs. 200–250 gm) retained MB longer in circulation, and had a shorter duration of MB‐induced hypotension. Spectrophotometric analysis of rat serum showed rapid elimination of MB from the vascular system, with a half‐life of 3.5 ± 1.9 minutes. While MB remains a useful vascular label, its rapid removal from the circulation and its hypotensive effect must be recognized. © 1992 Wiley‐Liss, Inc.
Accurate d‐spacings from zero‐order laue zone patterns
Authors: Le Page Y.
Published: February 2005

Experimental d‐spacing values are criteria towards the identification of crystallites by electron diffraction. Conclusive identifications often rely on accurate d‐spacings. It is shown here that accurate orthogonal components (in mm) for the primitive unit vectors of a zero‐level diffraction pattern can be obtained through least‐squares processing of (x,y) coordinates for all spots on the film. Valid vectors hom the origin spot to any spot in the plane of the film are integer linear combinations of the two selected unit vectors. Accurate lengths and standard deviations for such vectors therefore can be calculated from the least‐squares results. Corresponding d‐spacings can then be calculated from the vector lengths on the film and the camera constant. In order to obtain d‐spacing values that are not only precise, but also accurate, an accurate value of the camera constant should be used. This requires calibration of the experimental setup with reference materials in the same experimental conditions, with careful control of the sample height. For the same quality of measurements, the improvement in the accuracy of the d‐spacings obtained with the proposed method is approximately proportional to the square root of the number of measurements taken. Practically, typical improvement in accuracy is about threefold, and accuracies of a fraction of a percent in d‐spacings are achievable in this way. The above approach has been programmed as an option in the NRCBED program. © 1992 Wiley‐Liss, Inc.
InP sample preparation for the TEM by photochemical etching, ion milling, and chemical thinning
Authors: Lowes Theodore D. , Cassidy Daniel T.
Published: February 2005

Photochemical 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

This 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

Direct 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

The 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

The 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

The 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

The 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

Two 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

The 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

The 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

We 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

As 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

Methods 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

In 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

Smooth 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

Tritrichomonas 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

A 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.
High resolution and image processing of otoconia matrix
Authors: Fermin C. D.
Published: February 2005

This study was designed to investigate patterns of fibrils organization in histochemically stained otoconia. Transmission electron microscope and video imaging were used. These data indicate that otoconia of the chick (Gallus domesticus) inner ear may have central cores in vivo. The data also show that the ultrastructural organization of fibrils fixed with aldehydes and histochemical stains follows trajectories that conform to the hexagonal shape of otoconia. These changes in direction may contribute to the formation of a central core. The existence of central cores is important for the in vivo buoyancy of otoconia. Packing of fibrils is tighter after phosphotungstic acid (PTA) stained otoconia than with other histochemical stains, which usually produce looser packing of fibrils and seemingly larger central core. TEM of tilted and untilted material showed that turning of fibrils occurs at the points where the face angles of otoconia form and where central cores exist. Video image processing of the images allowed reconstructing a template which, if assumed to repeat and change trajectories, would fit the pattern of fibrils seen in fixed otoconia. Since it is highly unlikely that aldehyde primary fixation or PTA stain caused such drastic change in the direction of fibrils, the template derived from these results may closely approximate patterns of otoconia fibrils packing in vivo. However, if the above is correct, the perfect crystallographic diffraction pattern of unfixed otoconia do not correspond to patterns of fixed fibrils. © 1993 Wiley‐Liss, Inc.
A simplified mode of differential phase contrast lorentz microscopy
Authors: Kraut S. , Cowley J. M.
Published: February 2005

A simplified mode of differential phase contrast Lorentz microscopy for the study of magnetic domain structures in thin films is proposed and demonstrated. This mode employs a single annular detector in a scanning transmission electron microscope rather than the specialized split detectors that have been previously used. The resulting signal is sufficiently linear with magnetic field strength to allow quantitative data to be obtained on the domain configurations and the natures of the domain walls. © 1993 Wiley‐Liss, Inc.
A novel method for the cross‐sectional TEM preparation of thin films deposited onto water‐soluble substrates
Authors: Sáfrán György , Panine Pierre
Published: February 2005

A preparational method was developed solving the problem of cross‐sectional TEM preparation of thin films and layer systems deposited onto water‐soluble substrates. The technique is based on the replacement of the sample onto steady substrate, followed by mechanical and ion beam thinning. Cross‐sectional TEM micrographs of Ag and Ag/Ag2Se layers are shown presenting the efficiency of this novel technique. © 1993 Wiley‐Liss, Inc.
Cracking in albumen photographs: An ESEM investigation
Authors: Messier Paul , Vitale Timothy
Published: February 2005

The preservation of nineteenth‐century albumen prints is of great concern to collection managers and to conservators of photographic materials. In the field of art conservation, preservation techniques incorporating aqueous treatments are often used to enhance the long‐ and short‐term stability of historical artifacts or art objects. In a study of the interaction of water with albumen photographs, experiments were carried out in the ESEM to follow the real time effects of water on the prints. The experiments were designed to observe the effects of a range of relative humidities and liquid water on samples of expendable historic albumen prints, utilizing the advantages of imaging in the presence of water vapor. All albumen photographs exhibit a fine network of cracks in the albumen protein layer. Average crack width is approximately 10 μm. As observed in the ESEM, a 4.25‐fold increase in the width of a single crack (at 50% RH), viewed normal to the surface, resulted from a single controlled excursion to high relative humidity and immersion. In an extraordinary series of images, a print viewed in cross‐section exhibited a 22% swelling and shrinkage in thickness, and a 5% and 9% swelling and shrinkage along the width of a fragment of the albumen/image layer when the sample was immersed in water and dried. The visual information gained through the use of the ESEM helped to focus a materials investigation and served as a foundation for a study which shows that aqueous treatment causes increased cracking of both unsupported albumen and the albumen/image layer in prints. © 1993 Wiley‐Liss, Inc.
Morphology of nitric acid and water ice films
Authors: Keyser Leon F. , Leu Ming‐Taun
Published: February 2005

Ice films have been used to simulate stratospheric cloud surfaces in order to obtain laboratory data on solubilities and heterogeneous reaction rates. To obtain intrinsic uptake and surface reaction probabilities which can be applied to atmospheric models, it is necessary to carefully characterize these films. In the present study, environmental scanning electron microscopy (ESEM) is used to study thin films of both water ice and nitric acid ice near the composition of the trihydrate. The ices are formed by vapor deposition onto aluminum or borosilicate‐glass substrates cooled to about 200 K. Micrographs are recorded during the deposition process and during subsequent annealing at higher temperatures. The results show that the ice films are composed of loosely consolidated granules, which range from about 1 to 20 μm in size at temperatures between 197 and 235 K. Cubic water ice is sometimes observed at 200 K and converts to the hexagonal form at slightly higher temperatures. The loose packing of the granules confirms the high porosities of these films obtained from separate bulk porosity measurements. Average surface areas calculated from the observed granule sizes range from about 0.2 to 1 m2 g−1 and agree with surface areas obtained by gas‐adsorption (BET) analysis of annealed ice films. For unannealed films, the BET areas are about an order of magnitude higher than the ESEM results and imply that the unannealed ices contain microporosity which is lost during the annealing process. The present results have important implications for the extraction of intrinsic reaction probabilities from laboratory rate data. © 1993 Wiley‐Liss, Inc.
Oil sorption behavior of various sorbents studied by sorption capacity measurement and environmental scanning electron microscopy
Authors: Choi Hyung‐Min , Moreau Jerry P.
Published: February 2005

Oil sorption capacities of various natural and man‐made fibrous sorbents were compared in a simulated seawater bath containing oil. Natural sorbents such as milkweed, kapok, cotton, and wool showed higher sorption capacities than man‐made sorbents such as polyester, polypropylene, viscose rayon, nylon 6, nylon 66, and acetate. Sorption capacities of the natural sorbents were over 30 g oil/g fiber. No definite advantages were observed using man‐made bicomponent and biconstituent fibers over regular man‐made fibers with respect to their sorption capacity.

Analyses of sorption mechanisms using an environmental scanning electron microscope revealed that an oil deposit disappeared from the fiber surface after a certain time interval in milkweed, kapok, and cotton. This suggested that the sorption of oil in these fibers occurred through capillary action, probably due to their hollow lumens. Contrarily, adsorption, a surface phenomenon, would be the most prominent mechanism for oil sorption of wool fibers due to large amounts of surface wax, irregular scaly surfaces, and crimp. Effects of both adsorption and absorption were shown in the oil sorption of man‐made fibers, depending upon the type and shape of the sorbent. Dumbbell‐like oil deposits were seen on the fiber surface in certain oleophilic man‐made fibers, because of a partial wetting of oil on the fiber surface. For some hydrophilic man‐made fibers such as polyvinylalcohol and copolymer of isobutylene‐maleic anhydride, the physical configuration of the fiber was a decisive factor in determining oil sorpton capacity of the sorbents. © 1993 Wiley‐Liss, Inc.
Proposed healing and consolidation mechanisms of rock salt revealed by ESEM
Authors: Hwang Chao Lung , Wang Ming Liang , Miao Shuke
Published: February 2005

The grain boundary healing behavior of crushed rock salt was mainly studied by employing the environmental scanning electron microscope (ESEM) to study the consolidation mechanism of rock salt backfill. Dedicated miniature round rock salt specimens were prepared for observation of the water trapping effect by using a cold stage in the ESEM to reach saturation conditions. Comparable high pressure pellets were prepared for measuring the crystal growth. Consolidation tests using materials made at different pressures and containing different moisture levels were conducted in order to construct the proposed mechanism. Direct observation of specimens in the ESEM resulted in viewing water trapped on the surface and the formation of a water meniscus between two particles. The concentration of brine at the grain boundary was observed as contributing to the amount of recrystallization. From aforementioned observations, a schematic drawing of the dissolution and recrystallization process may be redrawn. The amount of water therefore has a great effect on the consolidation of rock salt and is possibly due to the sliding, rotation, or crushing of the contact zone of the granular material. From such a study, tentative healing and consolidation mechanisms can be deduced. © 1993 Wiley‐Liss, Inc.
Examples of evolution of microstructure in ceramics and composites
Authors: Brown P. W. , Hellmann J. R. , Klimkiewicz M.
Published: February 2005

In this article we describe a number of studies involving the direct observation of microstructural evolution. In general these investigations were carried out to establish the mechanistic paths involved. The materials studied range from fibers being evaluated for use in high‐temperature ceramic composites to energetic materials used as propellants. In particular we discuss the room temperature imaging of materials difficult to image by conventional means and the use of the chamber atmosphere to influence microstructural evolution. Imaging of hydroxyapatite formed by chemical means is briefly described as an example of a difficult microstructure. Microstructural evolution during calcium aluminate cement hydration relies on the chamber atmosphere to control moisture loss from the hydrating specimens. In some instances microstructural evolution with heating occurred independently of the chamber atmosphere. Grain growth in PZT films formed by sol‐gel processes depends strongly on temperature but does not appear to depend on the chamber atmosphere. This is also the case for the combustion of nitroamine propellants in that their combustion does not depend on access to an external source of oxygen. In other studies, the chamber atmosphere played an indirect role in determining microstructure. However, the mechanistic path driving microstructural evolution in copper‐based inks used as conductive paths on electronic substrates is atmosphere dependent. These inks are formulated from copper powder, glass, and an organic binder, and the interaction of the binder with an oxidizing atmosphere allows it to be burned out before significant interaction occurs between the copper powder and the glass. Finally, the microstructural variations during the oxidation of structural composites at high temperature were used to allow assessments of their likely failure mechanisms. © 1993 Wiley‐Liss, Inc.
Application of ESEM to fluxless soldering
Authors: Koopman Nick
Published: February 2005

The ESEM is ideally suited to study soldering processes. We have used it to observe solder reflow and joining in ambient gases. It reproduces effects of atmospheric pressure reflow in a hot stage light microscope, but with much better clarity and depth of field. Compared to a regular SEM, the ESEM offers advantages of atmosphere control and ability to observe the solder samples without carbon or gold coating. These coatings could interfere with the oxidation/reduction reactions which occur at the solder/ambient gas interface. Very thin surface films, especially oxide layers dramatically influence the flow of liquid solder and the ability of solder to wet or join to another surface. Fluxless processes in particular are ideally suited for study in the ESEM. We have used the ESEM to observe dynamic fluxless soldering and have recorded events on videotape for later stop‐action still pictures and slow motion photography. Examples of these processes are shown to illustrate the ESEM capability. Included are solder deformation structure, balling reflow of eutectic solder in hydrogen, balling reflow of eutectic solder in nitrogen, joining of two solder disks in nitrogen, and dynamic melting and freezing of an off‐eutectic dendritic alloy. All of these are observed in the absence of flux. © 1993 Wiley‐Liss, Inc.
3D‐structure of cells of human salivary glands as seen by SEM
Authors: Riva Alessandro , Valentino Luigi , Lantini Maria Serenella , Floris Alessandra , Riva Francesca Testa
Published: February 2005

To demonstrate by SEM the topography and cytoarchitecture of the different parenchymal components of human salivary glands, we have employed a number of techniques that allow either the exposure of internal and lateral cell surfaces or, following the removal of connective tissue, the visualization of endpieces, ducts, and myoepithelial cells.

Serous glands consist of indented acini attached to the ducts in a grape‐like fashion, whereas mucous and mixed glands are made up of smooth tubuli. Myoepithelial cells (mecs), which are abundant on the surfaces of acini, tubuli, and intercalated ducts, are sparse on striated ducts. They are star‐shaped on acini, striated ducts, and most of the tubuli. Spindle‐shaped mecs are seen, instead, on intercalated ducts and, occasionally, on mucous and mixed tubuli as well.

Cells of striated ducts split into a number of large basal portions whose surface is covered by long laminated processes responsible for the striations seen with TEM. Excretory ducts are lined by small cup‐shaped basal cells and by tall cylindrical cells, which are completely covered by short processes oriented at random. When observed from below, after removal of the basal lamina, the basal surfaces of cells of excretory ducts exhibit polygonal areas delimited by short reliefs. Those of striated ducts show, instead, long laminar processes arranged radially.

Results presented here are discussed and put in relationship to the mechanism of saliva production. © 1993 Wiley‐Liss, Inc.