Life Sciences Commons^™

Surface Visualisation Of Tissue Interfaces By Scanning Electron Microscopy. Methods For Exposure Of The Basal Lamina And Associated Structures In Human Amnion, T. D. Allen, J. D. Aplin, S. Campbell

Scanning Microscopy

Tissue interfaces such as basal lamina have been traditionally investigated in transmission electron microscopy by sections cut vertical to the lamina, presenting information restricted to a single ultrathin plane. In order to overcome this limitation, a methodology for surface visualisation of the underside cell membranes of the amniotic epithelium, the upper and lower basal lamina surfaces, and their relationship to the stromal collagen has been devised. This involves alkaline, detergent or enzymatic loosening and/or removal of the epithelial monolayer prior to fixation, followed by dry fracture after critical point drying. In this way we have visualised large areas of all …

Stopping Power For Low-Energy Electrons, R. M. Nieminen

Scanning Microscopy

Descriptions of inelastic processes for the slowing down of electrons in condensed matter are presented for the energy range between a few eV and a few keV. Attempts at quantitative theories of stopping are summarized, with an emphasis on obtaining useful cross section expressions for Monte Carlo simulations and analytic transport theories. Inelastic scattering with both electrons (conduction and core) and density fluctuations (phonons) are included. The main emphasis in the theories for the former is in the dielectric (self-energy) formulation for the conduction band and in using generalized oscillator strengths or semiclassical excitation functions for the core. Recent applications …

Contrast And Resolution Of Secondary Electron Images In A Scanning Transmission Electron Microscope, J. Liu, J. M. Cowley

Scanning Microscopy

Recent advances in the improvement of secondary electron image resolution to the subnanometer level demand further knowledge of the origin of secondary electron emission to interpret the experimental results. The generally accepted estimation of the non-localized range of the inelastic scattering of incident electrons and the subsequent generation of secondary electrons in a solid cannot explain the 0.7 nm resolution of secondary electron images obtained in a scanning transmission electron microscope operated at 100 kV. Resolution and contrast of secondary electron images are interrelated. High contrast as well as high resolution can be obtained at the same time. Contrast mechanisms …

Igg Receptors On Eosinophils: - Using Immune Scanning Electron Microscopy, Takumi Kishimoto

Scanning Microscopy

Using carboxylate modified latex particles covalently conjugated with anti-IgG, IgG receptors on eosinophils were examined with scanning electron microscopy (SEM). After block and inhibition tests, significant number of latex particles were confirmed to bound on the surface of eosinophils. Earlier reports described that density of eosinophils decreased in hypereosinophilic patients and the heterogeneity of eosinophils came into focus. Our experiment revealed that eosinophils of hypereosinophilic patients had more IgG receptors than those of normal volunteers. This difference might be due to the heterogeneity of eosinophils.

Preparation Of Isolated Blood Capillaries, R. C. Wagner, R. A. Buchanan, Ritchie Froehlich

Scanning Microscopy

Blood capillaries have been isolated from various tissue sources yielding suspensions of capillary segments. These have provided opportunities to study the cellular properties of capillary endothelium under conditions uncomplicated by the presence of stromal tissues and in which measured parameters can be attributed to endothelial cells. Fresh capillary isolates have been used directly as experimental systems but the yield of endothelium is quite low. Amplification of endothelial biomass has been accomplished by using freshly isolated capillaries as explants for primary tissue culture. It has not been previously possible, however, to obtain large amounts of capillary endothelium from a single preparation …

Determination Of Fiber Content In Long Fiber Reinforced Composites By Scanning Electron Microscopy And Image Analysis, R. F. Antrim

Scanning Microscopy

Currently, there is a wide interest in further developing long fiber reinforced composites. Due to the dependence of a material's mechanical properties to its microstructure, further development of microanalytical techniques is needed to quantify the amount of fiber. In response, a standardless technique was developed to determine the volumetric fiber content and its variation in an oriented long fiber reinforced composite. The method utilizes scanning electron microscopy to acquire backscattered electron images of polished cross-sections. The images are then processed to determine the fiber area fraction which, in this particular case, is equal to the volume fraction. The results presented …

Scanning Electron Microscope, Freeze Etching And Glycosaminoglycan Cytochemical Studies Of The Cerebellar Climbing Fiber System, Orlando J. Castejón, Haydée V. Castejón

Scanning Microscopy

Mouse and teleost fish cerebelli were processed by the freeze-fracture methods for scanning and transmission electron microscopy in order to study the three-dimensional morphology and intramembrane features of climbing fiber-Purkinje spine synapses. In addition, Alcian Blue and ruthenium chloride stainings were applied to mouse cerebellar tissue to investigate the polyanion composition of these excitatory synapses under the transmission electron microscope. In the granular layer, tendril and glomerular collaterals of climbing fibers were observed. In the molecular layer climbing fibers exhibited a characteristic crossing-over or arborescence pattern type of bifurcation, Scheibel's collaterals and multiple thorn synapses with Purkinje spiny dendrites. At …

Lymphoid Microenvironments In The Thymus And Lymph Node, W. Van Ewijk, P. J. M. Brekelmans, R. Jacobs, E. Wisse

Scanning Microscopy

The three-dimensional architecture of the thymus and mesenteric lymph node reveals several different stromal cell types important in the development and function of T cells. In the thymic cortex, T cells proliferate and differentiate in a meshwork of epithelial-reticular cells. They then migrate towards the medulla where they may interact with interdigitating cells. T cells migrate from the thymus through perivascular spaces, surrounding large vessels at the cortico-medullary boundary. In this area also large thymic cystic cavities are found, their function remains at present unclear. Mature "selected" T cells leave the thymus most probably by the venous bloodstream, to enter …

Changes In The Tracheal Ciliated Cells In Rabbits Treated By Cis-Diamminedichloroplatinum (Ii) As Studied By Electron Microscopy, M. Albertsson, C. -H. Hakansson

Scanning Microscopy

The ciliated epithelium of the rabbit's trachea was investigated after a single 5 mg dose of cis-diamminedichloroplatinum (cis-DDP). Specimens were taken for scanning electron microscopy, transmission electron microscopy and light microscopy. Examination was performed daily for 20 consecutive days. A cytotoxic effect of the drug on the ciliated epithelium was observed with bent ciliary tips, swollen tips and broken cilia. Finally the cilia were lost and large areas of the surface were covered with microvilli. However, 20 days after the drug injection, the restitution of the ciliary carpet was almost complete.

Scanning Electron Microscopy Studies Of Extended Defects In Semiconductors, C. A. Dimitriadis

Scanning Microscopy

Extended defects, such as dislocations and grain boundaries, play an important role in determining the performance of various semiconductor devices. This paper reviews applications of electron-beam-induced-current and cathodoluminescence scanning electron microscopy for the investigation of dislocations and grain boundaries in semiconductors. We developed a simple analytical method for the determination of the grain boundary recombination velocity and the minority carrier diffusion length, in contrast to a previous method which requires the use of a computer for the numerical calculation of an integral expression. We, also, studied theoretically the influence of an individual dislocation on the minority carrier lifetime. Investigation of …

Transport Models For Backscattering And Transmission Of Low Energy ( < 3 Kilovolts) Electrons From Solids, H. Lanteri, R. Bindi, P. Rostaing

Scanning Microscopy

This paper deals with the backscattering and the transmission of electrons with energy < 3 keV through thin self supporting films, or on bulk metals.

We present the main theoretical models used in such problems, and we analyse mainly the models based on the Boltzmann transport equation, similar to those developed in our laboratory.

For any model shown here, we try to give the precise domain in which they give reliable results as well as the limitations connected to the simplifying assumptions.

In the case of the most sophisticated model, we give original results for copper. The models are presented in a comparative form, and when it is possible we compare our …

Ultrastructural Characteristics Of The Fetal And Neonatal Rat Urinary Bladder, Samuel M. Cohen, Martin Cano, Takao Sakata, Sonny L. Johansson

Scanning Microscopy

The embryologic and neonatal development of the normal rat urinary bladder was investigated in Sprague-Dawley rats by light, transmission, and scanning electron microscopy from day 11 of gestation through 21 days of age. The epithelium at day 11 of gestation is composed of small, loosely-connected, rounded cells with occasional short microvilli on their surfaces. The large polygonal cells characteristic of the adult bladder begin to appear by day 15, but the microridges are not apparent until day 17. By day 20, the epithelium appears morphologically similar to the adult bladder. Several morphological features are observed at different times of gestation …

Effect Of X-Irradiation On Adenylate Cyclase Activity And Cyclic Amp Content Of Primary Human Fibroblasts, Z. Somosy, A. Takáts, Tamara Kubasova, F. Sudár, G. J. Köteles

Scanning Microscopy

Ionizing radiation provokes an increase of the cAMP level in several organs and body fluids. After reviewing the relevant literature we present the results of our own experiments on primary human fibroblasts. X-irradiation at doses of 0.5 and 2.5 Gy in vitro evoked a rapid and reversible increase of adenylate cyclase enzyme activity. A significant increase in cAMP level of these cells was also observed.

Adenylate cyclase was usually localized basolaterally on the surface of unirradiated cells, while irradiation resulted in a modification of distribution, i.e., the enzyme activity also appeared in apical localization.

An Experimental Scanning Capacitance Microscope, H. P. Kleinknecht, J. R. Sandercock, H. Meier

Scanning Microscopy

A fine needle stylus mounted to a three-dimensional piezo system is scanned across the sample in x-and y-direction, while a constant spacing between tip and sample, i.e., constant tip-to-sample capacitance, is maintained in z-direction. This is accomplished by vibrating the tip in z-direction at 1 kHz by typically 0.1 microns and by detecting the capacitance modulation from the shifting of the resonance of a tuned 1 GHz line. The horizontal resolution achieved so far is limited by the tip radius at about 200 nm and the vertical resolution is about 5 nm. The theoretical limits for finer tips are 7 …

Phenotypic Changes In The Megakaryocyte-Platelet Lineage, Paula E. Stenberg

Scanning Microscopy

Morphologic and phenotypic changes occur during the maturation of megakaryocytes (MK) from the pluripotent stem cell to platelets. As the MK acquires organelles, it also acquires membrane glycoproteins and granule contents. Platelet membrane GP IIb/IIIa and platelet peroxidase are present from early stages of maturation to the final product of the megakaryocyte, the platelet, while Ia-like antigen appears to be expressed only during early stages of maturation. The MK synthesizes increasing amounts of lysosomal enzymes, GP Ib, and alpha granule proteins as it matures from the megakaryoblast stage to the mature cell. The platelet contains only vestiges of a protein …

Ultrastructural And Functional Effects Of Lipopolysaccharide And Interleukin-2 On Human Nk Cells, Yuan-Hsu Kang, Mitchell Carl, Lorrita P. Watson

Scanning Microscopy

Bacterial endotoxin (lipopolysaccharide, LPS) and interleukin-2 (IL-2) are known to stimulate NK cell mediated cytotoxicity against tumor cells. In the present report we sought to correlate the stimulatory effect of LPS and IL-2 on NK cell activity with ultrastructural changes which occurred as a result of such stimulation. Peripheral blood mononuclear cells (PBMC) were purified from healthy donors by a Ficoll-Hypaque density gradient technique. Leu-11a⁺ NK cells were isolated by flow microfluorometry using a monoclonal FITC conjugated anti-Leu-11a antibody and a FACS II cell sorter. The PBMC were incubated, respectively, with E. coli LPS or recombinant IL-2 (IL-2) for …

The Ultrastructure Of Dentine From Rat Incisors Following Exposure To Sodium Fluoride And Potassium Pyroantimonate Staining, J. Appleton

Scanning Microscopy

Weanling rats were given a single intra-peritoneal injection of sodium fluoride and control animals normal saline for four consecutive days. The fluoride produced a consistent response in the mineralizing dentine of the incisors in which a hypermineralized band was succeeded by a hypomineralized band. Potassium pyroantimonate staining for calcium ions showed that following injection of fluoride, in contrast to the controls, there were large amounts of calcium pyroantimonate in the pre-dentine and throughout the odontoblasts. This suggests that fluoride temporarily affects the membrane enzyme systems which maintain calcium concentration gradients between the odontoblasts and the matrix. The resultant influx of …

Crystal Associated Diseases: Role Of Scanning Electron Microscopy In Diagnosis, K. P. H. Pritzker, P. -T. Cheng, M. D. Grynpas, D. P. Holmyard

Scanning Microscopy

As crystals are important etiologic agents for disease, their accurate identification in tissues and body fluids is of utmost importance. This paper surveys the roles of crystals in disease process and outlines current analytical techniques for crystal detection and identification in bone tissues. The value of multiple correlated techniques is demonstrated including scanning electron microscopy, x-ray energy spectroscopy and powder diffraction analysis. The current feasibility of utilizing intermediate voltage scanning transmission analytical electron microscopy to integrate these analytical techniques on the same tissue sample is emphasized.

Clinical Applications Of Electron Microscopy In The Analysis Of Collagenous Biomaterials, Arthur J. Wasserman, Charles J. Doillon, Alvin I. Glasgold, Y. Pedro Kato, David Christiansen, Azam Rizvi, Eric Wong, Jack Goldstein, Frederick H. Silver

Scanning Microscopy

Scanning and transmission electron microscopy are of clinical value in assessing the interaction between biomaterials and ingrowing tissues. Ultrastructural information allows the clinician and biomaterials specialist to determine events occurring during wound healing and the biocompatibility of prosthetic devices. This paper reviews some of the experimental and clinical studies done in our laboratory on the use of natural and reconstituted collagen as replacements for connective tissues. Consideration is given to collagen flakes used for the treatment of dermal ulcers, a collagen fiber prosthesis used for tendon and ligament replacement, the effects of chemical preservatives on cartilage used for replacement of …

Comparison Of The Calcium Distribution Pattern Among Several Kinds Of Hard Tissue Forming Cells Of Some Living Vertebrates, Yasutoku Kogaya, Kuhei Furuhashi

Scanning Microscopy

We investigated the ultrastructural distribution of calcium in several kinds of hard tissue forming cells (secretory and maturation ameloblasts, odontoblasts osteoblasts, chondrocytes, and osteodentine forming cells) of mammals, amphibians, and fish by use of the potassium pyroantimonate technique. The calcium distribution pattern is compared among these cells, and its biological significance is discussed. Except for mammalian odontoblasts, all types of the hard tissue forming cells exhibited fundamentally the same distribution pattern of calcium; the antimonate reaction product was mainly localized on the inner face of the plasmalemma and inside mitochondria. On the other hand, in mammalian odontoblasts, the reaction product …

Scanning Tunneling Microscopy Methods For Spectroscopic Imaging Of Subsurface Interfaces, L. D. Bell, W. J. Kaiser

Scanning Microscopy

A new method for spatially-resolved, spectroscopic investigation of subsurface interface structure has been developed. The method, Ballistic Electron Emission Microscopy (BEEM), is based on Scanning Tunneling Microscopy (STM) techniques. BEEM combines STM vacuum tunneling with unique ballistic electron spectroscopy capabilities. BEEM enables, for the first time, direct imaging of subsurface interface electronic properties with nanometer spatial resolution. STM topographic images of surface structure and BEEM images of subsurface properties are obtained simultaneously. BEEM capabilities are demonstrated by investigation of important metal-semiconductor interfaces.

Effect Of Fluoride And Cobalt On Forming Enamel: Scanning Electron Microscope And X-Ray Microanalysis Study, S. H. Ashrafi, D. R. Eisenmann, A. E. Zaki, R. Liss

Scanning Microscopy

The forming surfaces of enamel of rat incisors were examined by scanning electron microscope one hour after injection of either 5 mg/100 g body weight of sodium fluoride or 12 mg/100 g body weight of cobalt chloride. The cell debris from the surfaces of the separated incisors was either gently wiped off with soft facial tissues or chemically removed by treating with NaOH, NaOCl or trypsin. Best results to remove cell debris were obtained from 0.25% trypsin treatment.

SEM studies revealed that the surface of the normal secretory enamel was characteristic in appearance with well-developed smooth prism outlines. In fluoride …

Double-Axis Rotary Shadowing For High-Resolution Scanning Electron Microscopy, R. Hermann, J. Pawley, T. Nagatani, M. Müller

Scanning Microscopy

Thin continuous metal coatings and a scanning electron microscope-generated spot size in the range of the visualized particles, are necessary prerequisites if one hopes to extract high-resolution topographic information in the scanning electron microscope. Chemical fixation and dehydration in organic solvents at room temperature lead to severe ultrastructural artifacts which can be avoided by cryofixation and freeze-drying of the specimen. 0.9 to 2.7 nm thick homogeneous layers of chromium and germanium can be deposited onto the surface of cryofixed and freeze-dried specimens at high sub-zero temperatures by electron beam evaporation using "double-axis rotary shadowing". Theoretical calculations of the layer geometry …

Detectors For Quantitative Electron Beam Voltage Measurements, A. R. Dinnis

Scanning Microscopy

Qualitative voltage contrast is produced without difficulty in any SEM. Complete separation of the voltage contrast from other sources of contrast is not a straightforward matter because of the nonlinear relations between the phenomena causing contrast and the video signal.

Quantitative measurements depend on the availability of electron energy analysers which can detect accurately the shift in secondary electron energies due to potentials appearing on integrated circuit tracks, without being affected by transverse fields due to potentials on other conductors or insulators. The principles underlying existing detectors are explained, their effectiveness assessed, and a new form of electron detector is …

Signal Of Backscattered Electrons From Multiple Marks In Dependence On Mark Profile, D. Kaczmarek, Z. Czyżewski

Scanning Microscopy

The backscattered electron signal can be detected using a solid state detector system. Because this signal is affected by the surface topography it is necessary to determine the optimal detection condition for a registration mark detection in the electron-beam lithography and for an automatic topographical surface reconstruction.

The BSE signal from surface marks has been measured using semiconductor detectors with a small collection angle. Calculations of the BSE signal have been carried out by means of a simplified model of electron backscattering. The signal shape depends on some parameters of the mark profile, such as length, height and inclination angle …

Contribution Of Densely Distributed Electron Beam Induced Current Contrasts In Annealed Cz Silicon To Bulk Recombination, M. Kittler, W. Seifert

Scanning Microscopy

The paper presents a detailed analysis of Electron Beam Induced Current (EBIC) diffusion-length and contrast data for samples containing defect accumulations. The formulae given allow one to estimate to which extent the average diffusion length is determined by recombination-active defects showing EBIC contrast.

This analysis may be used to identify essential sources of bulk recombination in annealed silicon. In the light of our results stacking faults are an essential source of bulk recombination in intrinsically gettered p-type Cz silicon.

Mounting Materials For Automated Image Analysis Of Coals Using Backscattered Electron Imaging, W. E. Straszheim, K. A. Younkin, R. T. Greer, R. Markuszewski

Scanning Microscopy

In order to apply SEM-based automated image analysis (AIA) to the characterization of not only minerals in coal but to the coal itself, sample preparation methods need to be developed beyond common practice. A significant consideration is the degree of contrast achievable between the mount media chosen and the coal. Four low-atomic number materials (epoxy, polyethylene, polystyrene and carnauba wax) were compared for their potential as suitable mounting media for coal samples. Epoxy is satisfactory only for characterization of mineral particles since the contrast between epoxy and coal particles is negligible. Polyethylene or polystyrene have marginal application for use as …

The Use Of Backscattered Electron Imaging, X-Ray Microanalysis And X-Ray Microscopy In Demonstrating Physiological Cell Death, I. D. Bowen, N. A. Worrill, C. A. Winters, K. Mullarkey

Scanning Microscopy

The cytochemical localization of enzymatic activity by means of backscattered electron imaging (BEi) is reviewed and the application of BEI to changes in acid phosphatase and ATPase distribution during physiological (programmed) cell death in Heliothis midgut is explored. Programmed cell death entails the release of nascent free acid phosphatase as extracisternal hydrolase. This shift can readily be detected by means of the atomic number contrast imparted by BEI of the lead phosphatase reaction product, thus enabling the distribution of dying cells to be mapped. BEI is particularly useful in this context as it allows the examination of bulk specimens at …

Scanning Electron Microscopic Autoradiography Of Lung, K. E. Lauhala, C. L. Sanders, K. E. Mcdonald

Scanning Microscopy

Scanning electron microscopic (SEM) autoradiography of the lung is being used to determine the distribution of inhaled, alpha particle-emitting, plutonium dioxide particles. SEM autoradiography provides high visual impact views of alpha activity. Particles irradiating the bronchiolar epithelium were detected both on the bronchiolar surface and in peribronchiolar alveoli. The technique is being used to obtain quantitative data on the clearance rates of plutonium particles from bronchi and bronchioles.

The Influence Of Analyser Geometry Effects In Scanning Electron Microscope Voltage Contrast Measurements, Daniel S.H. Chan, Teck Seng Low, Wai Kin Chim, Jacob C. H. Phang

Scanning Microscopy

A computer simulation model used to study specimen dependent and analyser geometry dependent effects is described in this paper. With this model, the influence of the specimen dependent effect on quantitative voltage contrast measurements can be isolated from the analyser geometry dependent effect. Linearization error voltages in quantitative voltage contrast measurements arising from the individual influences of the specimen dependent and analyser geometry dependent effects are presented. The results show that the error component due to very narrow analysers dominate the total linearization error. The same situation arises when the voltage measurement point on the specimen is very near to …