bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of stereologic methods to stratified gingival epithelia*
Authors: Schroeder Hubert E. , Münzel‐Pedrazzoli Suzy 
Published: August 2011

SUMMARYStereologic point‐counting procedures were applied to estimate quantitative tissue and cytoplasm parameters of the oral and the junctional epithelium of the human gingiva. Three gingival biopsies of female children, obtained and processed under standardized conditions, served (1) to determine the minimal sample size of cytoplasmic area required for estimating representative volumetric parameters in different strata of both epithelia, and (2) to compare average volume and surface density data derived from standardized samples in epithelial cross sections cut at two planes orientated perpendicular to each other. Sampling of electron micrographs, performed at two levels of magnifications according to a systematic stratified random sampling procedure consisted of recording field strips parallel to the epithelial or tooth surface within each of the various strata. The optimal sample size required varied for different organelles and epithelial strata. Minimal sample size of cytoplasmic area per biopsy were 300–440 μm2 for basal, and 450 μm2 for stratum spinosum cells of oral epithelium, and 130–185 μm2 for basal cells of the junctional epithelium. Average morphometric parameters for gross tissue components (cells, nuclei, cytoplasm, intercellular space) which resulted from analysing 4900 μm2 tissue area in each of the epithelia in each biopsy, were almost identical when determined in two different section planes. Volume and surface density data of cytoplasmic organelles (mitochondria, rough and smooth endoplasmic reticulum, cytoplasmic filaments) resulting from a sample of 280 μm2 cytoplasmic area per stratum and biopsy, revealed differences of varying magnitude, when determined in the two section planes. These differences were markedly smaller than those between comparable strata of both epithelia. Discussion of sampling procedures concluded that the type of sampling used for the present study is suitable for comparative morphometric studies.
The selection of conditions for examination of specimens in a scanning electron microscope
Authors: Hearle J. W. S. , Lomas B. , Sparrow J. T. 
Published: August 2011

SUMMARYIn the past not much attention has been paid to the use of the most desirable conditions for examining a particular kind of specimen in a scanning electron microscope (SEM). The various factors affecting resolution in the SEM, namely those of beam diameter, beam penetration, contrast, signal‐to‐noise ratio and depth of focus, are examined. It is not possible in practice to eliminate all detrimental effects and compromises have to be made in instrumental settings, such as gun potential, lens currents, etc. in order to obtain the best image for a given specimen. This paper deals with the problems involved in examining textile fibres, metal surfaces and thin films with particular emphasis being made on the choice of gun potential and the amount of image detail observed. Examples are shown comparing micrographs taken using gun potentials of 5 kV and 20 kV, showing that due to electron‐penetration effects much surface detail is lost at the high gun potential. It is, therefore, useful to examine specimens initially at different accelerating voltages to determine if any desirable information is being lost due to the penetration of the electron beam. Some operating conditions are also given for use as a guideline for working at low accelerating voltages.
A technique for studying one and the same section of a cell in sequence with the light and electron microscope
Authors: Wells B. , Cour L. F. La 
Published: August 2011

SUMMARYMethods for mounting and staining relatively thin sections on electron microscope grids, in order that one and the same section of a cell can be photographed in sequence with the light and electron microscope are described. Toluidine blue is used as a stain and hexachlorabuta‐1,3 diene as a medium which enables the grid carrying the stained sections to be temporarily mounted under a coverslip and examined with an oil‐immersion lens. Results obtained with pollen mother cells of Fritillaria lanceolata at zygotene are illustrated.
Migration of potassium out of electron‐microscope specimens
Authors: Hodson Stuart , Marshall John 
Published: August 2011

SUMMARYWe have previously reported the direct detection of sodium and potassium in ultrathin biological sections (Hodson & Marshall, 1970a) by combining the technique of ultracryotomy (Hodson & Marshall, 1970b) with an electron‐microscope probe analyser EMMA‐4 (AEI, Harlow, Essex). We also suggested that it may shortly be possible to plot intracellular concentrations of sodium and potassium if our technique was made quantitative and tested critically. During such tests on organic membranes we discovered an unexpected phenomenon: when a beam of electrons irradiates material which includes potassium, the potassium may move out of the irradiated area.
Ruthenium Red staining of ultrathin sections of human mast‐cell granules*
Authors: Kobayasi Takasi , Asboe‐Hansen Gustav 
Published: August 2011

SUMMARYRuthenium Red was used for staining glutaraldehyde‐fixed ultrathin sections of mast cells embedded in Epon 812. The dye was dissolved in 0.1 M ammonia, or 0.1 N acetic acid or phosphate buffer at pH 7.4, 0.1 M at a concentration of 0.5%. The ammoniacal solution stained acid mucopolysaccharides of human mast‐cell granules more specifically than did the acetic solution. The probable site of the acid mucopolysaccharides is the finely granular material within the granules.
A method for the replication of articular cartilage surfaces suitable for the scanning electron microscope
Authors: Clarke Ian C. 
Published: August 2011

SUMMARYA method for replicating the surface of soft, wet tissue such as human articular cartilage is described. Silicone, acrylic and epoxy resins were tried. ‘Tensol‐7’ acrylic resin was found to be the most suitable replicating medium.
Preparation of human skin for high‐resolution scanning electron microscopy using phosphate buffered crude bacterial α‐amylase
Authors: Finlay J. B. , Hunter J. A. A. , Steven F. S. 
Published: August 2011

SUMMARYA technique for preparing human skin for high‐resolution scanning electron microscopy using phosphate‐buffered crude bacterial α‐amylase is described. Effects of the buffer solution alone are studied as well as the proteolytic activity of the enzyme solution used. The biochemical implications of these observations are discussed with regard to the in situ structure of the tissue.
On the accuracy of microinterferometric measurements of optical‐path differences by means of the half‐shade method
Authors: Pluta M. 
Published: August 2011

SUMMARYUsing a shearing double‐refracting interference microscope with a half‐shade eyepiece, the accuracy of optical‐path‐difference measurements has been examined. For the half‐shade elements, birefringent strips with phase difference equal to 180°, 110° and 20° as well as a half‐wave plate with a narrow slit, cemented between two glass plates, were used. It is known that different relative intensities of the background inside and outside the half‐shade strip introduce a subjective error in the correct visual assessment of the matching point of the interference image of the object under examination. Applying test objects made of thin strips of dielectric evaporated in vacuum onto glass slides, it has been demonstrated that this error depends upon the optical‐path difference and image size of the object being measured, as well as upon the half‐shade phase difference. For a small half‐shade phase difference the error is practically imperceptible and for the half‐shade strip giving half‐wave retardation it attains maximum values. In the case of homogeneous objects, the images of which are as large as 1.5–2° in the field of view of the microscope, this error does not usually produce inaccuracies greater than ± λ/100 in optical‐path‐difference measurements. Using the half‐shade strip with a diaphragm which masks the misleading background and enables an observer to see the matched image areas only, the optical‐path difference can be measured with accuracy ± 0.003λ or better.
Some microscopical investigations of grinding and abrasive wear*
Authors: Buttery T. C. , Archard J. F. 
Published: August 2011

SummaryThis work forms part of a broader investigation which explores the relationship between grinding and abrasive wear. Wear experiments were performed over a wide range of loads and speeds in which solid abrasives (typical of those in grinding wheels) were rubbed against metals (usually steels). Under certain conditions the rate of wear decreased with time; at the same time the worn debris changed from metallic particles to finely divided oxides and the surface of the abrasive became glazed. Optical and scanning electron microscopy have been used to study this transition in the wear mechanism and its relationship to the structure of abrasives and the nature of abraded surfaces. The investigation illustrates the role of microscopy in the examination of a complex engineering process.
A high resolution technique for the fine‐structural localization of acid hydrolases
Authors: Bowen I. D. 
Published: August 2011

SummaryAn azo dye technique is described for the fine‐structural localization of acid hydrolases. Enzymatically released primary reaction product, an insoluble substituted naphthol, is coupled with ρ‐nitrobenzene diazonium‐tetrafluoborate to produce a dense particulate azo dye. Simultaneous and post‐coupling procedures are employed. The method is potentially applicable to all acid hydrolases and is free from the artifacts which beset the commonly used lead salt methods. The localization of β‐glucuronidase and acid phosphatase in rat and slug liver is specifically dealt with here. Lysosomal and cytoplasmic sources of enzyme activity are revealed.
A comparison of two sampling procedures for stereological analysis of cell pellets
Authors: Mayhew T. M. , Williams M. A. 
Published: August 2011

SummaryElectron micrographs of macrophages within pellets of rat peritoneal exudate cells were analysed by the morphometric point‐counting technique to compare the volumetric and surface‐to‐volume parameters obtained by two distinct sampling procedures. The distinction between the two sampling procedures was dependent upon the nature of the cell profile recorded on the micrographs. The two types of profile compared were (1) equatorial profiles (each containing a substantial nuclear component to facilitate cell identification) and (2) mixed profiles (a random mixture of equatorial profiles, anucleate profiles and cell profile fragments). Exudate cells were obtained from normal animals and from animals stimulated 5 days previously by a single intraperitoneal injection of Freund's Complete Adjuvant in Hank's solution. Volumetric data for intracyto‐plasmic organelles were found to be in excellent agreement when the two sampling procedures were compared. In addition, the results gave satisfactory consistency for the recorded decrease in the surface‐to‐volume estimate of the stimulated macrophage. It is concluded that equatorial profile analysis, in which cell identification is facilitated by virtue of the presence of the nucleus, is suitable for comparative morphometric cytology in the present study and that the biased sampling procedure may have a wide applicability.
Quantitative autoradiography: an evaluation of visual grain counting, reflectance microscopy, gross absorbance measurements and flying‐spot microdensitometry
Authors: Goldstein D. J. , Williams M. A. 
Published: August 2011

SummaryKodak AR.10 and Ilford G5 autoradiographs of a variety of radioactive resin standards and labelled cell preparations were investigated by visual grain counting, reflectance microscopy, gross (non‐scanning) absorbance measurements and integrating microdensitometry (the last using the Vickers M85 flying‐spot instrument).The reflectivity of silver grains is affected by the type of radiation to which the emulsion was exposed, the conditions of development and other factors. Reflectance results in arbitrary machine units were converted to absolute units by comparing them with results obtained under identical experimental conditions on fully‐blackened standard autoradiographs.With relatively low grain counts, the exposure is approximately proportional to the visual grain count, the reflectance, the gross absorbance and the integrated absorbance. With a fractional coverage of emulsion by developed grains of more than about 0.4, or absorbance more than about 0.22 (corresponding with Kodak AR.10 to grain densities of more than about 1.5/μm2), the exposure remains directly proportional to the absorbance and the integrated absorbance; experimental observations confirmed the theoretical prediction that the apparent fractional coverage, as measured by reflectance microscopy, is approximately equal to unity minus the antilog of minus the absorbance.Visual grain counting is reliable in the range 0.01–0.4 grains/μm2 (about 30 grains/10 μm diameter cell), and although tedious is widely applicable. Reflectance measurements are objective and relatively rapid, and are useful with grain counts up to about 150 grains/cell, but results may be affected by staining of the emulsion or by fluorescence of the emulsion or specimen. Both gross and flying‐spot absorbance measurements are directly proportional to the exposure over a large range. Gross absorbance measurements are applicable only to extended, homogeneous autoradiographs, while integrating, flying‐spot measurements may be used also with discrete and non‐uniform specimens. Both absorbance methods are best applied to unstained preparations.
Nomarski differential‐interference contrast microscopy in transillumination: Its use on unstained or stained sections, smears, and wet mounts, or on fluorochromed sections and cell‐culture monolayers
Authors: Geissinger H. D. , Duitschaever C. L. 
Published: August 2011

SUMMARYUnstained, lightly stained and conventionally stained microtome tissue sections of two different thicknesses (ca. 4 μm and 1 μm) and also unstained or stained wet mounts of cells were photographed under the microscope using bright‐field, positive phase contrast, and Nomarski differential‐interference contrast (DIC) in transillumination. The photomicrographs were critically compared. It was found that the density of various stains did not adversely affect the better resolution of the DIC image (as compared to the bright‐field image); however, Optical sectioning' of darkly stained objects is not possible.Unstained or stained smears of blood or of epithelial cells of buccal mucosa were examined with DIC in transillumination, then after certain preparatory techniques, the same preparation was examined in the scanning electron microscope, and finally the same areas of the slide were viewed with DIC in epiillumination. Particular attention was given to structures (nuclei and cytoplasm) which appeared in positive or negative relief in the photomicrographs taken by the various techniques. It was concluded that the optically more dense nucleus which always appeared in positive relief by the various methods of examination, was in fact geometrically raised from the surrounding cytoplasm.Acridine orange (AO) stained cell‐culture monolayers and H and E stained sections were examined under a fluorescence microscope with DIC optics. By comparing photographs which had been taken with DIC, epi‐fluorescence or fluorescence in transillumination, and DIC‐fluorescence, it was concluded that the DIC image, which had been superimposed on the fluorescence image, contributed a definite gain in information.Some common errors in the interpretation of the DIC image are discussed; methods of avoiding improper use of equipment are given. The conclusion is drawn that the DIC system is superior to positive and negative phase contrast for the examination of a variety of unstained or stained preparations. Therefore, this method can be used to advantage not only for the examination of unstained preparations, but also on some specimens which have been routinely stained or fluorochromed.
Scanning electron microscopy of L‐phase streptococci
Authors: Bibel David J. , Lawson John W. 
Published: August 2011

SUMMARYProtoplasts and L‐phase variants derived from Streptococcus fæium strain F24 were studied by scanning electron microscopy. Effects on morphology due to several osmotic stabilizers, the duration and kind of fixation, the type of specimen mounting, and the method of drying were examined. Conditions for optimal results were found which will allow further biological study of the L‐phase. Whereas air‐drying of broth‐grown L‐phase variants was satisfactory, agar‐grown colonies required the critical point method.
Specific labelling of thiol groups in mammalian keratin suitable for electron microscope studies
Authors: Dobb M. G. , Murray R. , Sikorski J. 
Published: August 2011

SUMMARYQuantitative Polarographic studies of the reaction between methylmercuric iodide and variously reduced wool keratin indicate that reaction occurs specifically with the thiol groups from cystine. Since loss of protein from fibres is negligible, this organomercurial is preferred as a selective amino acid label in electron microscope studies. Similar reactions of wool with parachloromercuribenzoate (PCMB) result in extensive structural modifications.The mercury mercaptides were shown to be thermally unstable in the electron beam and cooling of the specimen between — 140°C and — 88°C coupled with low beam intensities was found necessary to study the original distribution of the mercurials in the samples. Since a direct relationship between the electron scattering sites of the mercurial and cystine within the keratin was established, it has been possible to demonstrate unambiguously for the first time that:(a) There exists a radial distribution of cystine within cuticular cells. Indeed a new sulphur‐rich component at the outer edge of the ‘a’ layer in peripheral cuticular cells has been identified.(b) Para‐cortical cells of intact keratin contain a higher proportion of cystine than ortho‐type cells.(c) A dense concentration of cystine labelled by the electron scattering centres (mercurials) corresponds closely to an intermicrofibrillar‐matrix system in the cortex.Furthermore, a method has been devised for determining the cystine content of the exocuticle using data obtained from electron micrographs.
Identification of structure by the common‐sense approach*
Authors: Elias Hans 
Published: August 2011

SUMMARYMistakes are often made and perpetuated in the three‐dimensional interpretation of single sections. Such errors can be avoided and corrected if the observer considers carefully what kind of three‐dimensional shape has the greatest probability of yielding profiles such as are seen in the microscope; and if he does not take certain published or verbal statements at their face value.
Recent progress in automatic image analysis*
Authors: Moore G. A. 
Published: August 2011

SUMMARYA general survey has been made of the present utility of computing equipment and automatic devices for common problems in stereology and morphometry. Three situations have been evaluated:(1) Commonly available computer facilities permit easy and rapid prediction of two‐dimensional measurement distributions characteristic of any mathematically defined spatial structure. Tabulated predictions can be computed by direct simulation of sampling processes and random perturbations may be introduced if desired. Resort to formal mathematical solutions is not normally required.(2) For purposes of controlling the quality of useful solid materials, the materials engineer can be satisfied by description of a Gestalt which characterizes the material as a whole and which can reasonably be presumed to control the behaviour of the material in service. Six stereologically valid parameters are sufficient to describe such a Gestalt. These are: volume fraction (Vv), mean free path in the matrix (l̄α), mean intercept width of particles (l̄β) and measures of material variability, general anistropy, and degree of patternness. Practical measurements of the latter parameters have been defined. Current scanner models are intrinsically suitable for these measurements but will benefit from standardized data outputs and improvements to increase measuring accuracy.(3) While Gestalt measurements may perhaps be applicable to some biological problems, many problems in this field are specifically concerned with the micro‐architecture of individual objects or cells. Micro‐architectural observations such as counting and measuring, or identifying, individual object sections are inefficiently performed in ordinary computers. Large programming effort is required for limited machine intelligence and the operating speeds are unsatisfactory. These machine operations are not yet competitive with human observers. A partnership combining human identification with machine measurement of identified objects is practical and equipment is presently available. There is reason to presume that computer methods of object identification which have been employed are not similar to the methods actually employed by humans. New hardware systems appear to be necessary either to obtain satisfactory operating speeds by known processes or, if possible, to economically simulate human processes of image recognition.
Applications of quantitative microscopy in materials engineering
Authors: Fischmeister H. F. 
Published: August 2011

SUMMARYAmong the examples reviewed are volume‐fraction measurements in phase diagram and kinetic studies, properties dependent upon internal surface area, the characterization of phase arrangements by contiguity, proximity and dihedral‐angle measurements. The use of grain boundary and particle spacings in studies of mechanical properties is discussed in relation to current theories of strengthening mechanisms. Applications of size‐distribution analysis in kinetic studies and in the assessment of inclusion contents in steels are surveyed.
Stereological characteristics of atomic arrangements in crystals
Authors: Mackay A. L. 
Published: August 2011

SUMMARYA major problem in dealing with complex structures is to identify simple parameters which will summarize significant information. For crystal structures the simplest measure is volume per atom. The Voronoi polyhedron (or Dirichlet region) about each atom can be calculated exactly or statistically. This has been done for a number of structures with unexpected results.Algorithms for examining the local atomic configurations by the calculation of N‐dimensional volumes are described. Other proposals for the statistical examination of known crystal structures are put forward. Crystals are significant in themselves and in that they provide model structures which can be handled exactly.Formulæ, convenient for handling the packing of spheres and polyhedra in N dimensions, are listed.
The texture analyser
Authors: Klein J. C. , Serra J. 
Published: August 2011

SUMMARYThe texture analyser is an apparatus for making morphological measurement which starts from a TV scan and specific hardware. We have conceived and realized this machine at the Centre de Morphologie Mathématique of the School of Mines of Paris. It inaugurates a new generation of apparatus in this field. It is based upon a new conceptual background, using the random set theory of G. Matheron, and the hit‐or‐miss transformation. Its sophisticated hardware is accessible but with the help of specific software. Thus, besides traditional measurements (e.g. lengths of intercepts) it allows the determination of new and useful parameters: radius of curvature, bi‐dimensional size distribution, covariance matrix, bi‐dimensional clumping measurements, and numerous other new parameters.