bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of six fixatives on the areas of rabbit neurons and rabbit and rat cerebral slices
Authors: Deutsch K. , Hillman H. 
Published: August 2011

SUMMARYCell bodies of cerebral neurons from rabbits were isolated by hand, transferred to a microscope slide in a ‘199’ medium, and the projected areas of their cytoplasm and nuclei were measured. In sixty‐four cells there was a strong correlation between the projected areas of the cytoplasm and the nuclei (r=0.66, P < 0001), and the ratio of the projected areas was 11.6. The medium was then replaced by the following fixatives: formalin (10% v/v), Bouin's, Carnoy's, Susas, glutaraldehyde (5% v/v), and osmium tetroxide (1% w/v). Cerebral slices were obtained from the grey and white matter of rabbit and rat, and were also measured before and after treatment with similar fixatives. Relative to the unfixed areas, glutaraldehyde and osmium tetroxide had no significant effect on the projected areas of isolated cells, Carnoy's fixative shrunk the areas of the cytoplasm by means of 16.26%, Bouin's by a mean of 49%, and Susas by a mean of 65%. The shrinkage of the cytoplasm and the nuclei was not significantly different from that of the nuclei for each of these three fixatives individually, but with formalin the mean shrinkage of the cytoplasm was 46% while the nuclei did not shrink significantly.Using the same fixatives the effect on the areas of the cerebral slides from rabbit and rat were as follows: glutaraldehyde and osmium tetroxide caused no change in area; Carnoy's, formalin and Bouin's fixative diminished the areas by a mean of 10–20%, and Susa's by a mean of 35%.It was concluded that a particular fixative often caused a different degree of shrinkage to the cytoplasm, nuclei and cerebral slice. In general, the lower the osmotic pressure of the fixative, the less shrinkage it induced.
Effect of Fixation on Cell Membrane of Early Embryonic Material as Observed On Freeze‐Fracture Replicas
Authors: Stolinski C. , Breathnach A. S. , Bellairs R. 
Published: August 2011

SUMMARYSome cell membranes of chemically fixed, cryoprotected and freeze‐fractured chick embryonic material are characterized by 150–250 nm diameter circular smooth blebs. No such blebs are observed, however, on cryoprotected, rapidly frozen but not chemically fixed samples. It is concluded, therefore, that fixation with buffered glutaraldehyde and not cryoprotection with glycerol is mainly responsible for the appearance of the blebs. The suggestion that blebs represent a budding virus is not tenable, since blebs are present in material obtained from virus free embryos.
Localization of Protein in the Rabbit Yolk Sac Splanchnopleur By Two Methods of Autoradiography
Authors: Williams E. W. 
Published: August 2011

SUMMARYThe distribution of protein labelled with radioactive iodine or tritium within cells of the yolk sac, after it was injected into the uterine lumen of pregnant rabbits, was studied by means of two autoradiographic techniques, one using the classical loop method of Caro & vanTubergen (1962), and the other using Normandin's direct deposition method (Normandin, 1973). The resolution of the latter method was found to be approximately 10 times more sensitive than that of the former (Hemmings & Williams, 1976); thus rendering the site of labelled protein easier to locate. Both techniques are reproducible, but the direct deposition method is easier to handle. Location of protein was detected within vacuoles, and sometimes free in the cytoplasm.
A Method For Photographic Densitometry of Scanning Electron Micrographs
Authors: Hatami‐Monazah Houshang , Boss Jeffrey 
Published: August 2011

SUMMARYA method is described for the study of the surface structure of mammalian chromosomes. Densitometric analysis of scanning electron micrographs permits the detection of regularities where overlying material obscures these in directly inspected micrographs. The method has been applied to the study of mammalian chromosomes.
A Simple Method For The Determination of Thickness and Grain Size of Deposited Films as Used On Non‐Conductive Specimens For Scanning Electron Microscopy
Authors: Røli Jakob , Flood Per R. 
Published: August 2011

SUMMARYLatex spheres in linear aggregates allow coating materials to accumulate only along their free surface. Transverse to the axis of the aggregate the diameter of a sphere will increase corresponding to the uncoated diameter plus twice the film thickness. Parallel to the axis of the aggregate the diameter of terminal spheres will increase with one film thickness, whereas the diameter of ‘enclosed’ spheres remain constant. By mounting uniform latex spheres on standard electron microscope‐grids and comparing the transverse to the parallel diameter of linearly aggregated spheres in the transmission electron microscope, the film thickness produced by various coating procedures has been determined. The grain size and crack formations in the films may be examined simultaneously.
Metallic Deposition in Specimens Presenting Cavities Using the Sputter Coater
Authors: de Slobodrian Maria‐L. Ligatto , de Estable‐Puig Rosita F. , Estable‐Puig Juan F. 
Published: August 2011

SUMMARYLocal charging effects in small biological cavities during SEM observation are apparent, even after sputter coating. Using an experimental model, the thickness of metallic coating at the bottom of cylindrical cavities has been measured and found to be less than 50% the thickness on the surface, depending on the relation of diameter to depth of the cylinder.
Electron Beam Heating Temperature Profiles in Moderately Thick Cold Stage STEM/SEM Specimens
Authors: Talmon Yeshayahu , Thomas Edwin L. 
Published: August 2011

SUMMARYThe analytic solution for the model of electron beam heating a moderately thick STEM/SEM specimen was used to calculate the steady state temperature profiles developed in the bulk of the specimen. For thin specimens one maximum in the temperature profile was found near the surface. The location of this maximum shifted away from the surface with increasing sample thickness. For specimens of thickness approaching the electron range two maxima were found: one close to the surface (as in thin samples) due to a ‘self‐insulating’ effect, and another maximum near the sample‐substrate interface—a result of very rapid increase in the energy loss by the electrons near their penetration range. These results are of particular interest for X‐ray microanalysis where high beam currents are used, resulting in potentially large temperature rises in the bulk of the specimen.
A New Freeze‐Etch Unit For Freeze‐Etch Rotary Shadowing, Low Temperature Freeze‐Fracturing and Conventional Freeze‐Etching
Authors: Elgsaeter Arnljot 
Published: August 2011

SUMMARYA new freeze‐etch unit is described in which one can make replicas where hydrated, frozen, fractured specimens rotate during specimen heavy metal shadowing. The freeze‐etch unit can also be used to do low temperature freeze‐fracturing and conventional freeze‐etching.
Freeze‐Fracturing of Biological Material With A New Specimen Table
Authors: Nickel Elvira , Oebel Gertrud , Pscheid Peter 
Published: August 2011

SUMMARYThe freeze‐fracturing of various biological material is described with the aid of a modified Balzers specimen table. The advantages of this table are easier and faster handling of the specimens and a better thermal contact between the specimen and the cold stage.
Application of Statistical Methods in Quantitative Microscopy*
Authors: Nicholson W. L. 
Published: August 2011

SUMMARYThe purpose of the paper is twofold: first, to describe the aspects of quantitative microscopy where statistical ideas are being applied today; and second, to describe some ways in which more complete use of statistics could improve quantitative microscopy. The typical estimation problem in quantitative microscopy is described with emphasis on the modelling of variability in estimation. A Poisson field model for imbedded particulates is used to illustrate the value of theoretical treatments of variability. Sampling, estimation and multivariate analysis are cited as areas of statistics presently used by quantitative microscopists. The potential role of statistics in quantitative microscopy is discussed. Examples from particle sizing and characterization of alveolar lung structure illustrate the value of statistical ideas. Automatic image analysers, while making the collection of large amounts of data feasible, have complicated statistical estimation. An investigation of the size distribution of random chord lengths through alveolar chambers illustrates how statistical methodology must be modified for valid inference.
Special Specimen Preparation Methods For Image Processing in Transmission Electron Microscopy: A Review*
Authors: Horne R. W. 
Published: August 2011

SUMMARYOne of the important developments in quantitative electron microscopy has been the application of optical and computer imaging methods to electron micrographs. In general these techniques of image analysis have been applied to electron micrographs from isolated biological structures prepared in the presence of various negative stains. To make full use of image processing techniques there are obvious advantages in preparing suitable specimens containing large areas of repeating features. However, the number of naturally occurring biological specimens exhibiting crystalline or paracrystalline features suitable for high resolution electron microscopy and subsequent image analysis is relatively small.Some recent experiments on the in vitro formation of crystalline and paracrystalline arrays from highly concentrated and purified isometric, filamentous and rod‐like viruses is reviewed. The problems associated with the preparative procedures for producing two‐dimensional and three‐dimensional crystalline arrays are discussed together with the possibility of extending the negative staining‐carbon film method for studying the gradual dissociation or assembly of viral components.
A simple laser microbeam system for cell irradiation
Authors: Marchant Harvey J. 
Published: August 2011

SUMMARYA simple adaptation to a vertical illuminator is described to allow a laser beam to be directed into the light path of a microscope where it is focused by the objective lens and used for cellular microsurgery. Any microscope to which a vertical illuminator can be fitted could similarly be used to micro‐irradiate specimens with a laser.
Quantitation in biological X‐ray microanalysis, with particular reference to histochemistry
Authors: Sumner A. T. 
Published: August 2011

SUMMARYThin specimens consisting of various light and heavy elements in gelatine have been subjected to X‐ray microanalysis to determine the relationship between the number of X‐ray counts for a specific element expressed as a percentage of the continuum (the percentage counts) and the concentration of that element. For light elements, the relationship between the percentage counts and concentration is strictly linear. For heavier elements, the relationship is not linear, because of the increase of the continuum counts with . If a correction is made for the effect of , heavy elements also show a linear relationship between percentage counts and concentration.Within the limits of atomic number (Z = 56) and concentration (∼ 10%) studied here, it is shown that when X‐ray microanalysis is carried out on bulk specimens consisting of various elements in gelatine, the relationship between X‐ray counts and concentration for a particular element is linear.The problems in quantitation of the results of X‐ray microanalysis caused by exogenous continuum and mass loss induced by irradiation are discussed. It is pointed out that when X‐ray microanalysis is used to study histochemical and other staining procedures, allowance must also be made for the reduction in concentration of other elements in the specimen as a result of the addition of the stain to the specimen.
Estimation of the mean caliper diameter of cell nuclei
Authors: Greeley Donald , Crapo James D. , Vollmer Robin T. 
Published: August 2011

SUMMARYIn morphometric studies of lung tissue, accurate determination of the total number of any specific type of cell, such as the endothelial cell, requires knowledge of the shape of the cell nucleus. This knowledge of shape is necessary to calculate the mean caliper diameter, which, in turn, is an indispensable element of the equation for the number of nuclei (therefore cells) per unit volume (Nv).Nine human lung endothelial cell nuclei were therefore reconstructed in dental wax from serial sections and were found to be pleomorphic triaxial ellipsoids. Five of these approached an oblate shape. The axes of these nine nuclear models were directly measured and a computer program using numerical integration was written to determine the mean caliper diameters of these ellipsoids.The estimated mean semi‐axes of the nine nuclei were (±SD) 5·98 ± 1·61, 3·61 ± 0·70, 1·36 ± 0·34; and the estimated overall mean caliper diameter for the total population of human lung endothelial nuclei was 7·97 ± 1·27 μm.
Estimation of the mean caliper diameter of cell nuclei
Authors: Crapo James D. , Greeley Donald A. 
Published: August 2011

SUMMARYMorphometric studies of lung tissue in which the number of cell nuclei (therefore cells) are determined require the determination of the mean caliper diameter for each type of cell nucleus studied. We determined the mean caliper diameter for the five most common classes of cells found in the gas exchange portion of rat lung. This was done by serially sectioning through ten nuclei from each class of cells and then constructing wax models of the nuclei. Most of the nuclei were found to be triaxial ellipsoids and direct measurements taken from the models were used to calculate the following estimated overall mean caliper diameters (±SE): alveolar type I nuclei, 7·97 ± 0·2 μm, alveolar type II nuclei, 6·77 ± 0·19 μm, interstitial cell nuclei, 7·64 ± 0·35 μm, endothelial cell nuclei, 7·22 ± 0·19 μm, and alveolar macrophage nuclei, 7·65 ± 0·17 μm.
A film holder for use with the Vickers M85/M86 microdensitometer
Authors: Sumner A. T. , Finlayson D. 
Published: August 2011

SUMMARYA film holder is described which allows the Vickers M85/M86 microdensitometer to be used to make transmission and density measurements on images on photographic film. This facility is particularly useful for applications such as making profiles of fluorescent banded chromosomes.
The use of simple image analysers in lung morphometry
Authors: Langston Claire , Thurlbeck William M. 
Published: August 2011

SUMMARYWe have used several commercially available image analysers to measure the inter‐alveolar wall distance on histologic sections of animal and human lungs. Inter‐ and intra‐observer variations using these machines are small, and very similar results are obtained using different machines. The recorded result depends on the magnification used since higher resolution produces more intercepts. The plane in which the measurement is made affects the result, representing the difference in shrinkage from fixed tissue to stained slides in the horizontal and vertical planes. Machine‐measured inter‐alveolar wall distances are smaller than those measured by humans because of the spurious intercepts made by the image analysers. However, the measurements are highly correlated and human‐measured inter‐alveolar wall distances can be closely predicted from the machine‐measured ones. The number of alveoli per unit volume is less well predicted from the average inter‐alveolar wall distance. Image analysers may possibly play a useful role in making similar simple measurements in other organs.
A simple method for maintaining relative positions of separate tissue elements during processing for electron microscopy
Authors: Stirling Charles A. 
Published: August 2011

SUMMARYMolten (328 K) 20% gelatin is used as a ‘glue’ to hold together separate tissue elements or tissue elements that may be separated when cutting small blocks of tissue for plastic embedding. Standard aldehyde and osmium fixation, dehydration and epoxy embedding are compatible with this as is semi‐thin sectioning for light microscopy or thin sectioning for electron microscopy.
A practical electron spectrometer for chemical analysis
Authors: Joy David C. , Maher Dennis M. 
Published: August 2011

SUMMARYThis paper describes the basic parameters which have been considered in the design of a practical electron spectrometer optimized for micro‐chemical analysis in a 100 kV transmission electron microscope fitted with a scanning unit. Constructional factors and the operation of this spectrometer are discussed, as well as data acquisition. Typical results are presented to illustrate the operative modes. Both the prototype spectrometer and subsequent copies of it now are being utilized sucessfully in studies related to materials and biological sciences.
The microstructure of glass fibre reinforced polyester resin composites
Authors: Guild F. J. , Silverman B. W. 
Published: August 2011

SUMMARYThe microstructure of a composite material is commonly defined by the volume fraction occupied by the fibres. An attempt is made to gain a more quantitative definition of the microstructure of unidirectional glass fibre reinforced polyester resin using data derived from a Quantimet 720 Image Analysing Computer.Sections to be examined under the Quantimet were cut perpendicular to the fibre direction and polished and etched such that the fibres appeared black. Values of the area covered by the fibres inside a small test cell, moved around the cross‐section in a contiguous grid, were determined; values for larger cells, made up of several adjacent test cells, were calculated from these.Two methods of analysis are presented. The first method involves the determination of the variance of the values of fractional area covered for different cell sizes. Information regarding the nature of the fibre distribution is sought both from comparing the variance values with those predicted for the null hypothesis, a random distribution, and from examining the shape of a surface defined by a variance matrix.The second method of analysis is based on the concept that a structure may be defined by its relationship to a structuring element. In the present case, structuring elements are squares and rectangles of empty space; the probability of finding such empty space is estimated. Information regarding the nature of the fibre distribution is sought from the probability matrices.
An iterative approach to the analysis of EM autoradiographs
Authors: Williams M. A. , Downs Angela 
Published: August 2011

SUMMARYThe errors inherent in EM autoradiography are discussed and certain of them deemed to be of particular practical significance in the quantitative assessment of preparations. A method is described for estimating the standard errors attributable to each of several sources of variation and thence for obtaining the overall standard error value to be attached to relative activity estimates obtained in the method of Downs & Williams (1978). In an appendix, a fully worked example is given illustrating clearly the strategy of the method and the magnitudes of error estimates that are to be attached to the final specific activity values.
A rapid preparation method for scanning electron microscopy of Lugol preserved algae
Authors: Bistricki T. , Munawar M. 
Published: August 2011

SUMMARYA method that utilizes samples preserved and stored in Lugol solution is described. The samples are postfixed in osmium tetroxide, rapidly dehydrated in absolute ethanol and dried by the critical point drying technique. Aliquots of several samples can be processed simultaneously. Surface details of algae stored in Lugol and processed by this method are comparable to those found in conventional preparative procedures. No loss of nannoplankton or other small sized fractions have been observed.
Negative staining of freeze‐fractured envelopes of Escherichia coli K12
Authors: Nermut M. V. , Burdett I. D. J. , Williams L. D. 
Published: August 2011

SUMMARYEnvelope fragments of E. coli K12 have been produced by freeze‐fracturing ‘by hand’ and negatively stained after thawing. The outer leaflet of the plasma membrane disintegrated upon thawing whereas the outer leaflet of the outer membrane did not. Negative staining revealed the following structural features on the outer membrane fragments: (i) ‘grooves’ 4–6 nm wide, (ii) spherical particles 6–8 nm in diameter, (iii) ‘black dots’ 3–8 nm in diameter.Treatment of cells with EDTA before freeze‐fracturing caused dilatation of grooves into holes eventually leading to fragmentation of the outer membrane.A mutant strain deficient in two outer membrane proteins fractured exclusively through the outer membrane. The outer leaflets so obtained disintegrated upon thawing similarly as observed for the outer leaflet of the plasma membrane.
Practical approach to the estimation of the overall mean caliper diameter of a population of spheres and its application to data where small profiles are missed
Authors: Greeley Donald A. , Crapo James D. 
Published: August 2011

SUMMARYIn the morphometry laboratory a practical, accurate, and computationally simple procedure is needed when the estimation of the number of spherical particles per unit volume (Nv) is pursued. In addition, this procedure should be able to deal with the very real problem of profiles too small to be counted.Two computationally simple methods, the size class analysis method and the mean profile diameter method, were examined in detail. Computer‐generated random profiles from various size‐distributions of spheres were analysed by both methods. The percents error to be expected with various sphere distributions with a relatively large number of missed small profiles were determined for both methods. The accuracy of the size class analysis method was poor when a significant number of small profiles were missed. In this situation the accuracy of this method could be greatly improved by applying a simple modification to the procedure. A size class was identified which was larger than the largest missed profile but smaller than the diameter of the smallest sphere in the population. All contributions of this size class and all smaller size classes were deleted from the computation of Nv.The mean profile diameter method was found to be difficult to apply to distributions containing missed small profiles. Missed small profiles were handled more predictably by the modified size class analysis method.
The estimation of neuronal population density by a robust distance method
Authors: Aherne W. A. , Diggle P. J. 
Published: August 2011

SUMMARYA new ‘nearest‐neighbour’ or ‘distance’ method of estimating neurone population density is introduced. The method was originally developed for ecological studies but can be imported into histology without significant modification; changes in population density can be estimated by inverting the measure of area per unit cell (the so‐called mean area). Its advantages include tests of randomness for the spatial distribution of the cells at issue and a robustness which can tolerate some departure from a random distribution pattern. To illustrate how the method is applied estimates of neurone density, in terms of ‘mean area’ per cell‐point, are made on a montage tracing of the human cerebellar dentate nucleus.