Biology Commons^™

Scanning Electron Microscopic Studies On Microvascular Architecture Of Human Coronary Vessels By Corrosion Casts: Normal And Focal Necrosis, T. Ono, Y. Shimohara, K. Okada, S. Irino

Scanning Electron Microscopy

Microvascular architecture of the normal human heart and myocardial focal necrosis were studied by scanning electron microscopy of corrosion casts. Casts macroscopically identical in form to the left ventricular posterior wall were prepared.

The following results were obtained in the normal human heart. (I) Most of the arterioles communicated with capillary plexuses smoothly and straight forwardly in the left ventricular posterior free wall. (2) Arterioles which branched from the arteries ran in various directions and continued into capillaries either at right angles or obliquely in the trabeculae carneae. (3) capillaries running parallel with the cardiac muscle fibers ran in different …

Intensity Of Valence Auger Transitions (L23vv) Of Al And Si In Metal, Oxide And Nitride, M. Gautier, C. Quennisset, J. P. Duraud, J. P. Vigouroux, C. Le Gressus

Scanning Electron Microscopy

L₂₃VV Auger transition has been studied in Si, SiO₂, Al, AlN, Al₂O₃ by electron spectroscopy excited either by electron beam or X Rays. A strong difference is observed in intensity between pure solid and oxide or nitride under electron bombardment. Auger intensity is very sensitive to changes in the backscattering coefficient or inelastic mean free path. However transient local trapping of electrons seems to be responsible for the large change observed.

A Summary Of Ion Beam Etching Of Biological Material With Special Reference To The Saddle Field Source, D. Claugher

Scanning Electron Microscopy

A brief review of etching of biological materials using radio frequency, ion beam and electrostatic focused sources. Results of experiments using fast atom sources to dissect pollen, diatoms, protozoa and small arthropods, indicate that they produce a much smoother result which enables investigations to be carried out at high magnifications with the SEM.

Physical Basis For Spectrometer Calibration, M. Gautier, J. P. Duraud, J. P. Vigouroux, C. Le Gressus

Scanning Electron Microscopy

Progress in quantitative surface analysis is hampered by the lack of experimental procedure including spectrometer calibration, sample preparation, and general experimental setting-up. Two methods for spectrometer alignment are compared: the linearization method and the elastic peak test. Experimental spectra are presented, which can be considered as stringent reference data to check the instrument response and the analyser transmission at low energies.

Principles Of X-Ray Spectroscopy, Edwin R. Levin

Scanning Electron Microscopy

X-ray spectroscopy has become an essential tool for obtaining local chemical constituent data, particularly for identifying features observed in imaging systems. This tutorial paper is intended to introduce the basic ideas of X-ray spectroscopy, especially to the newcomer to scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The primary focus is on energy-dispersive analysis (EDS); however, the close parallels with wavelength-dispersive analysis (WDS) are shown. Topics include electron beam-specimen interactions, X-ray generation and detection, spectral analysis, approaches to quantitation, and limits of detection and resolution.

Theory For Calcium-Phosphate Crystal Formation In Tissue From Scanning Electron Microscope Data, Alan C. Nelson

Scanning Electron Microscopy

Scanning electron microscope (SEM) morphological analysis combined with energy dispersive characteristic x-ray analysis provides insight into the mechanism of biological mineralization. A time series of tissue micrographs and mineralization measurements can permit the determination of the mineralization kinetic behavior and is the basis upon which a computer model has been devised. The computer model is constructed from fundamental principles of crystal nucleation and precipitation theory. Various general forms of the model are tested against the laboratory data for goodness-of-fit using the least squares method, and two models are found to be acceptable. Both of the acceptable models involve inhibition of …

Mineral Recognition And Liberation Degree Measurements In Industrial Ore Processing, G. Bonifazi, P. Massacci

Scanning Electron Microscopy

This study aims at identifying calculation procedures and representation methods for identifying the mineral species present in a rock. The goal of the study is to identify: the characteristic spectrum for each mineral species identified in the ore; the main shape of the individual species; the preferential arrangement of the individual mineral species; the grain-size distribution of the individual mineral species and of the grains resulting from comminution processes; the degree of liberation for each mineral; and the degree of liberation of the comminution products obtained from the ores.

Surface Studies Of Duodenal Lesions Induced By Thoracic Irradiation, K. E. Carr, S. Ellis, A. Michalowski

Scanning Electron Microscopy

Acute duodenal ulcers are produced in mice as a remote ("abscopal") effect of irradiation to the lower mediastinum. Such lesions have been examined with scanning electron microscopy at 5, 8 and 28 days after irradiation with 18 Gy of X-rays. All the ulcers occur within the first 1 cm long segment of the duodenum which is endowed with Brunner's glands. The single lesions vary in size, shape and position. The damaged area often includes much of the duodenal circumference and is distinguished by conical or rudimentary villi, or even by the complete absence of villi. In contrast, around the periphery …

Pollen Wall Structure, A New Interpretation, D. Claugher

Scanning Electron Microscopy

A new preparative procedure using potassium permanganate has enabled previously undescribed structures on the surface and in the walls of pollen grains to be visualised. The results in some respects lend support to predictions that have been made on the ultrastructure of walls which have not been imaged clearly by any presently available technique. The findings may necessitate a reappraisal of current concepts regarding pollen wall structure.

Cell Ultrastructure In Disease, R. Laschi, E. Govoni

Scanning Electron Microscopy

The doctor of today must adopt the 'cellular way of thinking' in the evaluation of diseases. This ultrastructural outlook provides him with much indispensable information that also serves a practical purpose. A diseased cell organelle is at the basis of every clinical sign and any attempt of therapy must be aimed at that specific point of lesion. We intend, in the light of a long experience, to propose to clinicians a new way of thinking in which a precise correlation between symptoms and sub-microscopic changes of the cell is considered. Many different examples amply justify this proposal. Electron microscopy can …

Exocytosis From Large Dense Cored Vesicles As A Mechanism For Neuropeptide Release In The Peripheral And Central Nervous System, Asa Thureson-Klein, Richard L. Klein, Pei-Chun Zhu

Scanning Electron Microscopy

Nerve terminals often contain morphological-distinct populations of large (75-110 nm) and small (45-55 nm) vesicles. The small vesicles are speculated to account for release of transmitter quanta as they accumulate at presynaptic membranes. Large vesicles can co-store neuropeptides and classical transmitters but their function in neurotransmission has been disputed because they do not appear to accumulate at chemical synapses. However, there is now evidence that the large vesicles play a role in neuro-transmission or its modulation even though they may not be eminently involved in synaptic release. Thus, exocytosis occurs along the synapse-lacking membranes of peripheral noradrenergic varicosities. Large vesicles …

Signal Generation And Contrast Mechanisms In Scanning Electron Acoustic Microscopy, N. Kultscher, L. J. Balk

Scanning Electron Microscopy

In scanning electron acoustic microscopy (SEAM) until now the signal generation is explained mainly by an intermediate production of thermal waves. Though this so-called thermal wave approach has proven to give realistic results for metals, from experimental evidence it seems to fail for other material groups such as ceramics, dielectrics, piezoelectrics and semiconductors. As these material groups are of major technological importance, it is necessary to develop theories which help interpreting those SEAM micrographs obtained for these types of material.

In a comparative manner three different models are discussed in this paper, the well known thermal coupling, the piezoelectric coupling …

Elemental Content Of Anagen Hairs In A Normal Caucasian Population Studies With Proton Induced X-Ray Emission (Pixe), B. Forslind, H. K. Li, K. G. Malmqvist, D. Wiegleb

Scanning Electron Microscopy

The elemental content of anagen hair fibers in a Caucasian population of healthy females and males in the age range 10-69 years was performed to constitute a baseline for further studies of pathological conditions. Proton induced X-ray emission (PIXE) analyses were performed on single hair fibers in triplicates from 103 individuals in order to determine sulfur, zinc, calcium, and chlorine content. The hair fibers were all anagen hairs collected from a site little influenced by genetic and hormonal influences 1.5 cm above the right ear of the probands.

An area 5-8 mm from the follicle bottom was chosen for minimize …

Lipofuscin Accumulation In Cultured Non-Dividing Cells As A Function Of Time And Oxygen Tension, Anders Brunmark, V. Peter Collins, Howard Thaw, Ulf Brunk

Scanning Electron Microscopy

Cultivated human glial cells, kept in a state of density-dependent inhibition of growth, accumulate age-pigment (lipofucsin) within their lysosomal vacuomes with the same characteristics as the corresponding pigment observed in vivo. The rate of formation and accumulation of lipofuscin is greatly accelerated under the conditions of routine cell cultivation in comparison to the in vivo event. Lipofuscin is generally considered to be composed of polymerized products of lipid peroxidation and thus it would be reasonable to suggest that factors which influence lipid peroxidation would also alter the rate of lipofuscin formation. Human glial cells were grown in the presence …

Calcium And Cystic Fibrosis, Godfried M. Roomans

Scanning Electron Microscopy

Cystic fibrosis (CF) is a generally lethal, congenital, genetic disease of unknown etiology. It is likely that a defective regulation of ion and water transport in exocrine glands and possibly also in other epithelial cells has a central role in the pathogenesis of this disease. Calcium has been implicated in the basic defect underlying CF because of findings of abnormally high calcium levels in some secreted fluids and some cells of CF patients.

Using X-ray microanalysis, we have demonstrated elevated calcium concentrations in cultured fibroblasts and in goblet cells of the bronchial epithelium of CF patients. A factor produced by …

Data Acquisition And Processing Techniques For Voltage Contrast Measurements, F. A. Dibianca, D. G. Johnson, C. R. Bagnell, E. I. Cole, W. V. Oxford, R. H. Propst, C. A. Smith

Scanning Electron Microscopy

The effects of several data acquisition techniques on the accuracy of voltage contrast measurements are studied. In particular, the effect of using a voltage reference region directly connected to an external voltage source in performing the image intensity-to-voltage mapping of a node whose voltage is to be determined is examined. This is found to allow improved voltage measurement. The actual reference curves were obtained by least squares fitting the measured intensity-voltage reference data alternately to a quadratic and a cubic function. In addition, various mapping algorithms are considered including ones based alternately on the use of unprocessed, subtracted and normalized …

Quantitative Renal Vascular Casting In Nephrology Research, Vincent H. Gattone Ii, Andrew P. Evan

Scanning Electron Microscopy

The present paper describes the use of a quantitative renal vascular casting method to study the changes associated with kidney disease. Several animal models of hypertension (spontaneously hypertensive rat, SHR, with its normotensive rat the Wistar Kyoto, WKY; Dahl salt sensitive DS - hypertensive, and salt resistant DR -normotensive) were examined at time points when the systemic blood pressure was rising (6 and 12 weeks of age) and following renal denervation (in SHR-WKY rats). The SHR appears to have a smaller caliber afferent arteriole at both 6 and 12 weeks of age. This difference is probably not entirely due to …

A Review Of Modern Characterization Methods For Semiconductor Materials, T. J. Shaffner

Scanning Electron Microscopy

The manufacture of solid state devices in the microelectronics industry involves crystal growth, slice preparation, diffusion and implantation, oxide and metal deposition, patterning and etching, probe testing and packaging of completed devices. This simplified process flow is adopted in an overview to briefly outline some established as well as newly developed techniques of materials characterization. The complexity of semiconductor processing has imposed greater stringency criteria which have resulted in the revitalization of old methods as well as the development of new techniques capable of extreme sensitivity and spatial resolution.

Examples given for trace impurity and dopant detection include neutron activation …

Plant Ultrastructure In The Scanning Electron Microscope, Susan H. Barnes, Stephen Blackmore

Scanning Electron Microscopy

Preparative techniques which have been used to study internal details of plant cells in the scanning electron microscope are reviewed. A number of methods have previously been described which involve selective extraction of materials from freeze-fractured surfaces and can be referred to as freeze-fracture and cytoplasmic maceration. One of these techniques which involves an extended period of cytoplasmic maceration with dilute osmium tetroxide has been applied to the study of Cichorium intybus (chicory) pollen ontogeny. The results obtained, including changes in the numbers of mitochondria and the form of endoplasmic reticulum during the course of development demonstrate the value of …

Surface Morphology Of Unused And Used Hydromerr-Coated Intravenous Catheters, A. Bylock, E. Hultman, B. Gustavsson, L. E. Linder, I. Curelaru

Scanning Electron Microscopy

Hydromer^R-coated polyurethane (Erythroflex)^R catheters, unused, or intravenously inserted for 2-20 days, were studied by scanning electron microscopy (SEM). Both unfixed and fixed (2% glutar-aldehyde in phosphate buffer), and air-or critical-point dried (CPD) specimens were investigated. The catheter segments were sputter-coated with approx. 20 nm gold and studied at an accelerating voltage of 20 kV. The specimens were examined for surface depositions, thickness and structure of the Hydromer^R layers, and occurrence of adhering and embedded bacteria.

The outer Hydromer^R layer showed, in the un-used specimens, scratches and fissures, as well as adhering foreign bodies. In used …

Concerning The Problem Of High Depth Resolution Using Ion Sputtering, G. Blaise

Scanning Electron Microscopy

The inhomogeneity of ion bombardment, the angular dependence of sputtering yields and the crystalline orientation of samples are the three main causes of the degradation of resolution with depth. It is possible to reduce these effects by bombarding at low energy (≈ 1 keV). A low-energy ion-bombardment device is described which has been adapted for use on our sputtered thermal-ion source mass spectrometer.

The Quick-Freezing Of Single Intact Skeletal Muscle Fibers At Known Time Intervals Following Electrical Stimulation, Rashid Nassar, Nancy R. Wallace, Isaiah Taylor, Joachim R. Sommer

Scanning Electron Microscopy

Single intact frog skeletal muscle fibers quick-frozen after known time intervals following electrical stimulation are examined electron microscopically in thin sections, after freeze-substitution, in freeze-fracture/etch preparations, and in cryosections prepared for x-ray microprobe analysis. Techniques are described to perform these operations on a single fiber. Notable morphological differences between conventionally fixed and cryopreserved muscle fibers, and between fibers quick- frozen at different post-stimulation intervals are demonstrated.

Scanning Electron Microscopy Of Human Metaphase Chromosomes, T. D. Allen, E. M. Jack, C. J. Harrison, D. Claugher

Scanning Electron Microscopy

Preparative methods for scanning electron microscopy of chromosomes are dependent on the original source of material. Chromosomes extracted from unfixed metaphase cells via isolation buffers tend to show topography and surface morphology which may have been induced by the choice of isolation buffer itself. Furthermore, this type of preparation often precludes any chromosome identification, as many metaphases have been pooled, and also the chromosomes from these preparations are not suitable for the banding techniques regularly used in clinical cytogenetics. Our own approach has been to use the standard cytogenetic approach, starting with methanol-acetic acid fixed, air dried metaphase spreads, allowing …

Deconvolution In Auger Electron Spectroscopy, B. Chornik, H. E. Bishop, A. Le Moel, C. Le Gressus

Scanning Electron Microscopy

Deconvolution calculations have been applied in Auger Electron Spectroscopy to increase resolution and/or to eliminate loss features. We present: i) A short review of the methodology; ii) Recent results obtained in our laboratory in spectroscopy of Al, Ni, Cu, Ag and Te; iii) A discussion on the conditions for the appearance of artefacts originating either in the calculation or the physical processes (emission anisotropy, distribution of electron path lengths, and intrinsic losses).

Analytical Ultra High Vacuum Scanning Electron Microscopy With Field Emission Gun For Surface Study, P. Morin, P. Abraham, C. Bablet, M. Tholomier

Scanning Electron Microscopy

Surface studies can be carried out with a scanning electron microscope (SEM) having an ultra high vacuum specimen chamber. The main application of this SEM was the micro Auger analysis, but it is also interesting to combine the usual surface study technique with SEM observations. Indeed, these latter give valuable in formation about the topographic, chemical and crystallographic aspects of the surface when the secondary, backscattered and transmission SEM modes are used. The SEM performances are increased by the use of a field emission gun, the high brightness beam of this gun gives new observation possibilities such as the imaging …

Cytoskeletal Changes During Adhesion And Release: A Comparison Of Human And Nonhuman Primate Platelets, J. C. Lewis, M. S. White, T. Prater, K. R. Porter, R. J. Steele

Scanning Electron Microscopy

The organization of cytoskeletal proteins in whole-mount adherent platelets from African green monkeys and normal human volunteers has been studied by SEM, high vacuum electron microscopy (HVEM) and conventional (120 kV) electron microscopy. We describe three distinct organizational zones, the Central Matrix, the Trabecular Zone and the Peripheral Web in spread platelets from both sources. The Central Matrix is an ill-defined superstructure of 80-100 Å filaments of short length which enshrouded the granules, dense bodies, mitochondria and elements of the open-channel and dense-tubular systems. The latter, identified through the use of peroxidase cytochemistry with the whole mounts, is an anastomosing …

Comparison Of Preparative Techniques For Scanning Electron Microscopy Examination Of Soybean Seed Coats In Sectional View, Daniel M. Baker, Harry C, Minor, Merton F. Brown

Scanning Electron Microscopy

Various scanning electron microscopy preparative techniques have been used by researchers to examine sectional views of dry, mature soybean (Glycine~ CL.) Merr.) seed coats. Such previously employed techniques were utilized In our preliminary investigations of seed coat structure, but often yielded unacceptable preservation. Consequently, eight preparative techniques were evaluated In an effort to define conditions required to obtain consistently high quality preservation of soybean seed coats In sectional view. Of the eight procedures tested with the cultivar Williams 82, razor sections and mechanical fractures of dry seed coats yielded the poorest definition of anatomical features. Samples soaked In water prior …

Long Term Effects Of Radiation And Combined Modalities On Mouse Lung, David P. Penney, Paul Van Houtte, Dietmar W. Siemann, Wayne A. Rosenkrans Jr., Philip Rubin, Robert A. Cooper Jr.

Scanning Electron Microscopy

The lung appears to be the major dose-limiting organ in radiation of the thorax. Early responses (<1 week) involve the type II pneumocyte and increased surfactant biosynthesis and secretion. Later changes, which appear to be related to the surfactant response, lead to classical radiation pneumonitis, which is often fatal. Animals which survive radiation pneumonitis develop progressive fibrosis, a late-appearing response, which reduces compliance and available air space, and is usually fatal. This study centers on the fine structural changes in the lungs of LAF₁ mice, 63 weeks following various radiation exposures (5-13 Gy). Doses which are subthreshold in evoking surfactant and pneumonitic responses precipitate fibrosis and atelectasis by 63 weeks, and involve type II pneumocyte sloughing and degeneration. Of the two major deterrents to lung irradiation (pneumonitis and fibrosis), these results suggest that fibrosis always follows pneumonitis, but pneumonitis is not a necessary preliminary step to fibrosis. Bleomycin elicits several morphological alterations characteristic of radiation, and, when combined with the latter, appears to exacerbate radiation effects.

Characterization Of Small Metallic Clusters By Electron Energy Loss Spectroscopy, M. Acheche, C. Colliex, P. Trebbia

Scanning Electron Microscopy

Small spherical tin and gallium clusters (diameters in the range 2 to 80 nm), prepared with a liquid metal ion source, were analysed in a scanning transmission electron microscope (STEM) by electron energy loss spectroscopy (EELS). Both volume and surface plasmon excitations were investigated and their dependence on the cluster size interpreted by classical and quantum mechanical models. A blue shift of the volume plasmon energy with decreasing radius R of the cluster was clearly detected. The full width at half maximum (FWHM) of the peak, related to the damping of the volume plasmon excitation, showed a dependence in 1/R. …

Opportunities For Electron Microscopy In Space Radiation Biology, J. T. Lett

Scanning Electron Microscopy

Densely ionizing, particulate radiations in outer space are likely to cause to mammalian tissues biological damage that is particularly amenable to examination by the techniques of electron microscopy. This situation arises primarily from the fact that once the density of ionization along the particle track exceeds a certain value, small discrete lesions involving many adjacent cells may be caused in organized tissues. Tissue damage produced by ionization densities below the critical value also afford opportunities for electron microscopic evaluation, as is shown by the damage produced in optic and proximate tissues of the New Zealand white rabbit in terrestrial experiments. …