Biology Commons^™

Enhanced Floral Analysis By Low Temperature Scanning Electron Microscopy, Brenda Brookes, Ernest Small

Scanning Microscopy

Traditional methods of preparation of botanical specimens for scanning electron microscopy (SEM) have proven to induce artifacts in some specimens which often reduce quality of resulting images, and are highly misleading for taxonomic purposes. The advantages of low temperature SEM are illustrated by an investigation of freshly collected flowers, using a cryo-system interfaced to an SEM. This method overcame the deficiencies of traditional procedures to produce exceptional images of floral surfaces in their natural state. Depending on the nature of the material under investigation, the method my be indispensable (e.g., for accurate details of petal surfaces), preferable (e.g., glandular hairs …

Myocyte Swelling And Plasmalemmal Integrity During Early Experimental Myocardial Ischemia In Vivo, Martin D. Sage, Robert B. Jennings

Scanning Microscopy

Using scanning and transmission electron microscopy, the structure of myocytes early in the phase of irreversible injury induced by 40 minutes of severe regional ischemia has been investigated, paying particular attention to the effects of cell swelling on the SEM appearance of the myocytes. Swollen myocytes showed an increased space beneath the plasmalemma and between organelles. True subsarcolemmal blebs were not seen and the attachment complexes between the Z-band and the underlying myofibrils remained intact. The proportion of the PS face of the plasmalemma which appeared "en face" (0.70%, SD:1.22 vs 5.0196, SD:3.72) in freeze-fracture faces of ischemic tissue was …

The Effect Of Fatigue On Essential Element Distribution In The Rabbit Masseter, M. B. Engel, J. K. Bressman

Scanning Microscopy

The rabbit masseter is composed of mainly fast fatiguable type IIB fibers which give a positive mATPase reaction at pH 9.3. To study the effect of fatigue on the distribution of some crucial elements, the masseter was stimulated electrically for 45 minutes. The contralateral muscle served as a control. Control and experimental tissues were rapidly excised, and frozen in isopentane cooled to -150°C in liquid nitrogen. Sections were cut in a cryostat and prepared by freeze-drying. Water content of fatigued muscle was significantly higher than controls: 79.3% versus 77.3%. The fatigued state was verified by glycogen depletion viewed in PAS-stained …

Materials Analysis By Mass Spectrometry Of Sputtered Neutrals, Hans Oechsner

Scanning Microscopy

Mass spectrometric detection of neutral surface particles released by ion bombardment has become an important method for surface and depth profile analysis. Its fundamental difference to secondary ion mass spectrometry SIMS is the separation of the formation of the analyzed particles and their ionization. Hence, matrix and selectivity effects influencing SIMS signals in a mostly unknown manner via the ionization process in secondary ion emission are avoided in general.

The different techniques being presently employed for the necessary postionization of the sputtered neutrals are reviewed and discussed with respect to their potentialities. Secondary Neutral Mass Spectrometry (SNMS) using efficient postionization …

Ion And Water Retention By Permeabilized Cells, Carlton F. Hazlewood, Miklos Kellermayer

Scanning Microscopy

Nonionic detergents, Triton X-100 and Brij 58, removed, within 2-5 minutes, lipid membrane of suspended thymus lymphocytes and monolayer H-50 cells grown in culture. Studies of hydration, ionic asymmetry, and ionic and protein release kinetics were conducted on these membraneless cellular preparations. The hydration of nuclei isolated by Triton X-100 procedures appears to be influenced strongly by the monovalent ionic concentration of the buffer bathing the organelles. The putative monovalent ionic concentration of the cellular aqueous phase (i.e., 150 meq/L) caused nuclei to swell and coalesce. Monovalent ionic concentrations of 30 meq/L or less caused minimal changes in volume and …

3-Dimensional Imaging Of Biological Structures By High Resolution Confocal Scanning Laser Microscopy, G. J. Brakenhoff, H. T. M. Van Der Voort, E. A. Van Spronsen, N. Nanninga

Scanning Microscopy

Imaging in confocal microscopy is characterized by the ability to make a selective image of just one plane inside a specimen, virtually unaffected -within certain limits-by the out-of-focus regions above and below it. This property, called optical sectioning, is accompanied by improved imaging transverse to the optical axis. We have coupled a confocal microscope to a computer system, making the combination of both an excellent instrument for mapping the 3-dimensional structure of extended specimens into a computer memory/data array. We measured that the volume element contributing to each data point has, under typical fluorescence conditions, a size of 0.2 x …

Junction Electron-Beam-Induced Current Techniques For The Analysis Of Photovoltaic Devices, R. J. Matson

Scanning Microscopy

A number of useful electron-beam-induced current (EBIC) techniques have evolved through the study of junction behavior in photovoltaic (PV) devices in cross section as a function of light and voltage bias, temperature, and electron beam scanning parameters. The necessary hardware modifications, the techniques themselves, and their applications are presented. In the case of PV devices, light and/or voltage biasing the entire device while electron probing it in cross section permits the observation of the distribution of the narrowing or extension of the space-charge region. Monitoring the junction behavior as a function of temperature has at least two applications. In situ …

The Correction For Extraneous Background In Quantitative X-Ray Microanalysis Of Biological Thin Sections: Some Practical Aspects, Godfried M. Roomans

Scanning Microscopy

The correction for extraneous continuum is of great importance in the quantitative analysis of thin sections of biological tissue. Although a theoretical model for this correction is available, its application in practice meets with problems. In this paper, a model system, consisting of sections of homogeneous plastic on copper mesh grids was used to identify sources of inaccuracies in the quantitative procedures. An unmodified electron microscope was operated under standard analytical conditions. It appeared that geometrical factors connected with the position of the analysis relative to the grid bars were of prime importance. The correction for the contribution of the …

High Resolution Secondary Electron Imaging In A Scanning Transmission Electron Microscopy Instrument, J. Liu, J. M. Cowley

Scanning Microscopy

High resolution and high quality secondary electron (SE) images can be obtained in a dedicated scanning transmission electron microscopy (STEM) instrument under normal operating conditions. Small gold particles less than 1 nm in diameter can be imaged in the SE mode and fine details on surface morphology can be revealed clearly by secondary electron imaging. Applications of SEM study of surface step structures are presented. Secondary electron image intensity variations of different MgO smoke crystals with electron beam irradiation time are discussed. Contrast mechanisms for secondary electron imaging of specimen surfaces and future improvements in obtaining ultra-high resolution SE images …

A Possible Site Of Calcium Regulation In Rat Exocrine Pancreas Cells: An X-Ray Microanalytical Study, Norbert Roos

Scanning Microscopy

We analysed four subcellular compartments in rat exocrine pancreas cells, zymogen granules, cytoplasm surrounding the zymogen granules, mitochondria and cytoplasm in the basal part of the cells for sodium, magnesium, phosphorus, sulfur, chlorine, potassium and calcium content, using ultrathin frozen-dried cryosections. The highest concentrations of calcium were measured in the zymogen granules and the surrounding apical part of the cell containing Golgi apparatus, smooth endoplasmic reticulum and condensing vacuoles.

Calcium concentrations in the basal part of the cells (mostly rough endoplasmic reticulum) were 60% lower than in the apical part of the cells. The lowest calcium concentrations were measured in …

Proton-Induced X-Ray Emission Spectrometry In Archaeology, C. P. Swann, S. J. Fleming

Scanning Microscopy

Proton-induced x-ray emission (PIXE) spectrometry is fast developing a reputation as a powerful analytical tool in the study of a range of ancient materials, including bronze, iron, gold, glass, faience, and smelting slag. PIXE data allows determination of the primary constituents which would indicate their recipe of production and determine their bulk physical properties (e.g., color of a glass, brittleness in a metal), and of a wide range of trace elements which may indicate the source of raw material s from which an artifact was constituted. Over the past seven years, PIXE spectrometry's primary advantage over other recognized methods now …

Influence Of Cytomatrix Proteins On Water And On Ions In Cells, I. L. Cameron, G. D. Fullerton, N. K. R. Smith

Scanning Microscopy

This review concerns the influence that cytomatrix proteins have on the motional properties of water and on the major inorganic ions in cells. The techniques we used for study of water in cells and on the cytomatrix proteins include: pulsed NMR of water protons, quench cooled ice crystal imprint size, and osmotic behavior. The technique for study of ions involved use of electron-probe X-ray microanalysis of thin cryosections of cells. The cytomatrix was found to play the major role in determining the extent of hydration water in cells, The amount of hydration water varied greatly between cell types (e.g., lens …

Thermal Enhancement Of Cellular Radiation Damage: A Review Of Complementary And Synergistic Effects, G. Peter Raaphorst, J. G. Szekely

Scanning Microscopy

Hyperthermia treatment can kill mammalian cells in a time and temperature dependent manner. Thermal sensitivity varies extensively among various cell lines in culture and cellular molecular and ultrastructural studies have not resolved which cellular mechanisms underlie thermal cell killing and radiosensitization. The response of cells to heat and radiation are complementary under certain conditions found in human tumors, such as hypoxia, low pH, low nutrient and the S-phase of the cell cycle. Thus, hyperthermia can be used as a complementary treatment modality in the radiotherapy of human cancer. Further studies show that heat treatment causes radiosensitization which is in part …

Sertoli Cell Death By Apoptosis In The Immature Rat Testis Following X-Irradiation, David J. Allan, Glenda C. Gobé, Brian V. Harmon

Scanning Microscopy

The importance of the morphological study of cell death has recently been emphasized by the recognition that the ultrastructural features of dying cells allow categorization of the death as either apoptosis or necrosis. This classification enables inferences to be drawn about the mechanism and biological significance of the death occurring in a particular set of circumstances.

In this study, Sertoli cell death induced in the immature testis of three and four day old rats by 5 Gy (500 rads) x-irradiation was described by light and transmission electron microscopy with the objective of categorizing the death as apoptosis or necrosis. The …

The Surface Characterization Of Modified Chrysotile Asbestos, J. K. De Waele, F. C. Adams

Scanning Microscopy

In this paper, results of a semi-quantitative and qualitative leaching study of chrysotile and Chrysophosphate® fibers in oxalic acid and succinate salt buffer solutions with laser microprobe mass analysis (LAMMA) and electron probe X-ray micro-analysis (EPXMA) are presented, which demonstrate clearly the potential of these sensitive surface analytical tools for the analysis of natural physico-chemically modified and depleted fibers. These results are verified with those obtained by atomic absorption spectroscopy (AAS) for the measurement of the leached magnesium and iron concentration in solution. In order to study differences in adsorption behaviour and reaction capability between natural and chemically modified chrysotile, …

X-Ray-Induced Cell Death By Apoptosis In The Immature Rat Cerebellum, Brian V. Harmon, David J. Allan

Scanning Microscopy

The cells of the external granular layer (EGL) of the developing cerebellum are known to be particularly sensitive to radiation. In the past, changes induced in this layer by irradiation have been referred to by non-specific terms such as "pyknotic cells" and the mode of cell death has been assumed to be necrosis. However, in published light micrographs of these dying cells, the appearance is suggestive of apoptosis, a distinctive mode of cell death which occurs spontaneously in normal adult and embryonic tissues and can also be triggered by certain pathological stimuli.

This light and transmission electron microscopic study of …

Scanning Electron Microscopy Of Early Atherosclerosis In Rabbits Using Aortic Casts, Ralph G. Kratky, Margot R. Roach

Scanning Microscopy

Our research involves measuring the size and location of atherosclerotic lesions on the intimal surface of arteries. To this end we have developed a new method in which scanning electron micrographs of vascular casts with impressions of these lesions on their surface are used. This method is compared with light microscopy and scanning electron microscopy of tissue with lesions. All three methods are found to detect lesions equally well. We also examine the cellular elements in the lesion to determine how the images are formed.

Response Of Laryngeal And Tracheo-Bronchial Surface Lining To Inhaled Cigarette Smoke In Normal And Vitamin A-Deficient Rats: A Scanning Electron Microscopic Study., P. K. Jeffery, A. P. R. Brain, P. A. Shields, B. P. Quinn, T. Betts

Scanning Microscopy

The effects on surface morphology of airway epithelium of cigarette smoke (CS) inhalation alone (experiments one and two) or of CS in combination with hypovitaminosis A (experiment two) was investigated using specific pathogen free rats. Eight morphologically distinct cell types were distinguished overall. Apart from atypical squamous lesions each of the other cell types could be found in varying proportions in all experimental groups. CS alone caused an increase in the frequency with which intra-lumenal mucus was seen and an increase in the occurrence of secretory cells of types IV (i.e.,'merocrine') and V (i.e.,'apocrine'). In experiment one, the area of …

Surface Morphology Of Human Airway Mucosa: Normal, Carcinoma Or Cystic Fibrosis, P. K. Jeffery, A. P. R. Brain

Scanning Microscopy

The study presents preliminary qualitative findings of an investigation of grossly normal main and lobar bronchi at sites distant to well circumscribed tumour (n=15), adjacent to tumour (n=5) or of airways obtained during heart/lung transplantation in patients with cystic fibrosis (CF, n=3). In the normal airways the surface epithelium was on average 50 𝝁m thick, pseudostratified and rested on a roughly contoured basement membrane. A variety of cell types were identified although many were obscured by a dense covering of cilia, occasionally interrupted by foci of squamous metaplasia. Submucosal gland structure was observed in chance vertical fractures of the airway …

The Surface Morphology Of Normal And Atherosclerotic Coronary Arteries In Male Macaca Fascicularis And The Effect Of Coronary Angiography, Dwight A. Bellinger, Jon C. Lewis, Thomas B. Clarkson

Scanning Microscopy

Selective coronary angiography is one of the procedures used frequently in the diagnosis and management of coronary artery disease. Macaca fascicularis monkeys were used to study the effects of coronary angiography on coronary artery surface morphology. Fourteen M. fascicularis were fed either an atherogenic diet (0.34 mg of cholesterol/kcal and 40 to 43% of the calories as fat) for six to nine months or a control diet. For six of these animals the Judkin method of selective left coronary angiography was done 24 h prior to necropsy. The ascending aorta, right coronary artery, left circumflex (LCX), left anterior descending (LAD) …

The Versatility Of Scanning Electron Microscopy In Thin Film Device Analysis, D. J. Drake, W. G. Hawkins, R. W. Anderson

Scanning Microscopy

The versatility of scanning electron microscopy is shown for many stages of fabrication of thin film transistor driver matrices for actively addressed liquid crystal displays. Electron channeling and Schottky barrier charge collection modes allow rapid assessment of silicon crystal quality. The secondary electron mode allows examination of conductor lead crossover integrity. A form of voltage contrast is used on the completed array to monitor performance of the array prior to liquid crystal filling.

Image Simulation For Secondary Electron Micrographs In The Scanning Electron Microscope, David C. Joy

Scanning Microscopy

The interpretation of high resolution secondary electron images, and quantitative measurements of micrometer size features on integrated circuits, both require accurate modelling of the process of image formation in the scanning electron microscope. A Monte Carlo model, based on the semi-empirical theory of Salow, has been developed which permits the simultaneous computation of the secondary and backscattered yields. The physical constants necessary to apply this model can be derived from straightforward measurements of the total electron yield as a function of beam energy. On the basis of simplifying assumptions line profiles and images can then be simulated for specimens of …

Trophectoderm: The First Epithelium To Develop In The Mammalian Embryo, Lynn M. Wiley

Scanning Microscopy

The first epithelium to appear during mammalian embryogenesis is the trophectoderm, a polarized transporting single cell layer that comprises the wall of the blastocyst. The trophectoderm develops concurrently with blastocoele fluid production as the morula develops into a blastocyst. The process whereby the morula becomes a fluid-filled cyst is called 'cavitation', which can be regarded as the first functional expression of the trophectoderm phenotype. The outer layer of eel ls of the morula comprise the nascent trophectoderm and are already morphologically polarized prior to the onset of cavitation. A major working hypothesis in the field of mammalian embryogenesis is that …

The Inorganic Geochemistry Of Coal: A Scanning Electron Microscopy View, Robert B. Finkelman

Scanning Microscopy

The scanning electron microscope (SEM), equipped with an energy dispersive X-ray analyzer (EDX), has been widely used to study the inorganic geochemistry of coal. This system was instrumental in establishing that the bulk of most trace elements in bituminous coals are associated with fine-grained accessory minerals. Textural evidence, as observed in the SEM, indicates that many of these minerals are embedded in relatively large organic particles. As a consequence of this association, these minerals, and the elements they contain, can be rafted up into the lighter specific gravity fractions during sink-float separation of the coal. Textural evidence also indicates the …

Scanning Electron Microscopy And Electron Probe Microanalyses Of The Crystalline Components Of Human And Animal Dental Calculi, R. Z. Legeros, I. Orly, J. P. Legeros, C. Gomez, J. Kazimiroff, T. Tarpley, B. Kerebel

Scanning Microscopy

A review of the use of scanning electron microscopy (SEM) and electron probe microanalyses in the study of dental calculus showed that such studies provided confirmatory and supplementary data on the morphological features of human dental calculi but gave only limited information on the identity of the crystalline or inorganic components.

This study aimed to explore the potential of combined SEM and microanalyses in the identification of the crystalline components of the human and animal dental calculi. Human and animal calculi were analyzed. Identification of the crystalline components were made based on the combined information of the morphology (SEM) and …

Applications Of Transmission Electron Microscopy To Coal, C. A. Wert, K. C. Hsieh, Mike Buckentin, B. H. Tseng

Scanning Microscopy

Coal consists of a hydrocarbon matrix in which minerals are embedded. The hydrocarbon matter also contains impurities distributed as individual atoms. Thus, coal has phases similar to those in metallic or ceramic alloy systems; a matrix, included precipitates and atoms distributed individually in solid solution. Consequently, techniques of electron microscopy developed to examine metallic and ceramic alloy systems are directly applicable to coal. We report application of microanalytical techniques of electron microscopy to coal using examples of measurements for several coals. Identification and characterization of clays and sulfides is described. Use of x-ray emission spectroscopy for organic element measurement is …

The Bulk Specimen X-Ray Microanalysis Of Freeze-Fractured, Freeze-Dried Tissues In Gerontological Research, I. Zs.-Nagy

Scanning Microscopy

The rationale for choosing the freeze-fracture freeze-drying (FFFD) method of biological bulk specimen preparation as well as the theoretical and practical problems of this method are treated. FFFD specimens are suitable for quantitative X-ray microanalysis of biologically relevant elements. Although the spatial resolution of this analytical technique is low, the application of properly selected bulk standard crystals as well as the measurement of the intracellular water and dry mass content by means of another method developed in the same laboratory, allow us to obtain useful information about the age-dependent changes of ionic composition in the main intracellular compartments. The paper …

Response Of Mouse Lung Air-Blood Barrier To X-Irradiation: Ultrastructural And Stereological Analysis, L. De Saint-Georges, U. Van Gorp, J. R. Maisin

Scanning Microscopy

Male mice of the Balb/c strain were exposed, at an age of three months, to a single dose of 10 or 20 Gy on the right hemithorax. At 3, 4, 6, 9 and 12 months after exposure, lungs were processed for electron microscopy following a standardized procedure in order to allow stereological analysis. By this method, the arithmetical mean thickness and, the air-blood barrier mean thickness in the lung parenchyma was shown to increase quickly with time by oedemization and fibrinization of the septal space. The ratio endothelium/epithelium surfaces (Sr/SF) gradually decreased by reduction of both surfaces but this was …

Impurity Lattice And Sublattice Location By Electron Channeling, S. J. Pennycook

Scanning Microscopy

A new formulation is presented for the use of crystallographic orientation effects in electron scattering to determine impurity lattice location. The development of electron channeling techniques is reviewed and compared to high energy ion channeling and to the Borrmann effect in x-ray diffraction. The advantages of axial over planar geometry are discussed. Delocalization effects are more serious for quantitative analysis than have generally been believed. The new formulation applies to any crystal lattice and quantitatively includes delocalization effects via c-factors, which have been experimentally determined for diamond structure semiconductors. For sublattice site location this formulation removes the two major approximations …

Electron Beam Testing Of Passivated Devices Via Capacitive Coupling Voltage Contrast, W. Reiners, K. D. Herrman, E. Kubalek

Scanning Microscopy

By fundamental experiments and theoretical treatments a detailed understanding of the capacitive coupling voltage contrast {CCVC) has been gained, demonstrating that this technique is, in principle, applicable to a non-destructive testing of passivated integrated circuits (IC) by means of electron beams. In fact, however, several problems have to be eliminated in order to introduce this testing technique into a production line procedure.

In a first step, preconditions have to be met. These are a primary electron (PE) energy where the electron yield is greater than one and a sufficiently low extraction field above the IC. Secondly, as CCVC vanishes within …