bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of three different electron microscopical grade glutaraldehydes used to fix ovarian tissue
Authors: Weakley Brenda S.
Published: August 2011

‘EM grade’ glutaraldehydes from three suppliers were tested for the following: (1) pH of stock solution, (2) 235/280 nm UV absorbance ratio, (3) milliosmolarity of 2% and 4% solutions, (4) quality of fixation produced in ovarian tissue by fixatives prepared from each stock solution. Low pH of the stock solution appeared to be the most detrimental factor in fixation. Fixatives with a low 235/280 nm ratio (between 0·18 and 0·67) did not give good fixation regardless of the pH of the stock solution. Fixatives made from stock solutions with a pH above 4 and a 235/280 nm ratio between 1 and 2 resulted in the best preservation of ultra‐structure. Variations in milliosmolarity from one batch of stock solution to another were encountered, but appeared to have no correlation with the quality of fixation.; Received 1 October 1973; revision received 20 December 1973
The use of X‐ray microanalysis to investigate problems encountered in enzyme cytochemistry*
Authors: Ryder T. A. , Bowen I. D.
Published: August 2011

The nature of the reaction product and non‐specific staining obtained using lead salt methods, for localizing phosphatase activities, has been determined using energy dispersive X‐ray microanalysis. The detectability of ‘non‐electron dense’ elements has permitted the development of an alternative azo dye method involving the coupling of an enzymatically released, insoluble primary reaction product with the active diazotate of 2, 5‐dichloroaniline (Fast Scarlet GG). The resultant azo dye was detected in ultrathin cryosections. The localization achieved by this method and the advantages of combining ultracryotomy and X‐ray microanalysis with enzyme cytochemistry is discussed.
Microscopical communication
Authors: Turner G. L'E.
Published: August 2011

Microscopy poses special problems of communication because it reveals completely unfamiliar images to the eye. During the eighteenth century, scientific societies, private letters and the sale of standard specimens satisfied the largely amateur interest in microscopy. The need to illustrate texts came rather later than might be expected, however, because the development of the optics of the instrument was very slow between its invention in about 1600 and the discoveries of J. J. Lister in the 1830s. In the second half of the nineteenth century the microscope increased in scientific importance, creating a need for rapid and efficient means of communicating results, to which photography and new printing techniques were essential. This development is illustrated with special reference to the publications of the Royal Microscopical Society.
Ultrastructure research in biology before the introduction of the electron microscope
Authors: Frey‐Wyssling A.
Published: August 2011

Before the introduction of the electron microscope for cytological research around 1940, indirect methods were used for disclosing sublight‐microscopic structures. The results obtained by macromolecular chemistry were combined with those from investigations made with polarized light and by X‐ray diffraction. The application of Wiener's theory of composite bodies proved the presence of rodlet and lamellar ultrastructures, and the X‐ray analysis gave information on the crystallinity and the size of the components of such structures.

Both methods are based upon regular periodicities in the object investigated, so that their application is limited. Nevertheless, most of the conclusions concerning ultrastructural morphology gained with these techniques were corroborated when direct images of the relevant ultrastructures could be produced by electron microscopy.
A cryostat approach to ultrathin ‘dry’ frozen sections for electron microscopy: a morphological and X‐ray analytical study
Authors: Appleton T. C.
Published: August 2011

Conventional preparative procedures for the examination of tissues in the electron microscope involve the use of fixatives, dehydration in alcohol or acetone, embedding in plastics and staining. Such procedures remove soluble components and are therefore often unsuitable for chemical analysis of naturally occurring electrolytes. Ultrathin frozen sections of unfixed, unembedded biological tissue can be cut onto dry glass knives, freeze‐dried and viewed in the electron microscope without staining. Morphological detail is sufficient to identify cell types and ultrastructure. X‐ray microanalysis in the analytical electron microscope (EMMA‐4) has shown that highly soluble electrolytes can be detected and that intracellular compartments are retained.
Measurement of the top bottom effect in scanning transmission electron microscopy of thick amorphous specimens
Authors: Gentsch P. , Gilde H. , Reimer L.
Published: August 2011

In Scanning Transmission Electron Microscopy (STEM) details at the top of thick specimens can be imaged with a better resolution than those at the bottom, because the scanning electron probe is broadened by multiple scattering. For quantitative measurement we used a test specimen consisting of a substrate film with an island‐structured indium film and coated with polystyrene spheres of different diameters up to 1.1 μm. The fine detail contained in the indium film was observed and the beam broadening was that caused by the polystyrene spheres. This specimen was imaged with the spheres both above and below the layer, in a JEOL 100B electron microscope with a scanning device. Electron energies from 20 to 100 keV were used. Images with the sphere below show a higher resolution than those with the sphere above and also those of conventional electron microscopical images at 100 kV and 200 kV. The broadening of the edges on the photographic film was recorded with a microdensitometer. The results can be compared with theoretical calculations by a Monte Carlo method. There is a good agreement with the experiments if one uses an effective aperture obtained by transmission experiments.
A precise stage arrangement for correlative microscopy for specimens mounted on glass slides, stubs or EM grids
Authors: Geissinger H. D.
Published: August 2011

The instrumentation necessary for precise and fast correlation of images derived from a light optical microscope (LM) and a scanning electron microscope (SEM) operated in the reflective mode, is described. The specimens can be mounted on standard microscope slides (25 × 75 mm), SEM‐stubs (12 mm ø), or on transmission EM grids (3 mm ø). The instrumentation consists of two parts: an attachable precision stage for an LM, and an attachable slide carrier for the stage of an SEM. By taking into account the vernier readings of the stages of both microscopes (LM and SEM), identical particles in a specimen can be found instantaneously under either microscope. Therefore it is concluded that the use of this instrumentation in correlative microscopy (LM → SEM → LM) is time saving, and especially recommended on fragile biological specimens, which may deteriorate rapidly under the electron beam of an SEM.
Advances in atom‐probe field ion microscopy*
Authors: Müller Erwin W.
Published: August 2011

The ToF atom‐probe FIM is a microanalytical tool of ultimate sensitivity. Design and performance of the three presently operating instruments are described, including applications to metallurgical problems and contributions to basic effects in field ion microscopy. Up to four‐fold ionic charges of metals, field adsorption of noble gases, and the occurrence of metal‐helide ions have been surprising results. The mass resolution of present atom‐probes is marginal due to random ion energy deficits. A new energy deficit compensated atom‐probe offers a very satisfactory mass resolution of 1/1000.
Trends and prospects in scanning electron microscopy
Authors: Hayes Thomas L.
Published: August 2011

Scanning electron microscopy is developing towards increased analytic capabilities such as characteristic X‐ray analysis as a routine adjunct to the topographic image. At the same time improved instrumentation will make higher resolution possible for both ultra‐thin and bulk specimens. Some of the newer techniques for specimen preparation are also noted.
A note on Aherne's method of counting tissue components in relatively thick sections
Authors: Freedman L. S.
Published: August 2011

Aherne's method of estimating the number of components NV per unit volume in relatively thick sections is briefly described. Next, formulae are given which lead to an unbiased estimate of NV when the components are identical spheres. This is done for the situations (i) where there is perfect contrast and (ii) where there is contrast deficiency. Aherne's approximation for small objects is compared to the unbiased estimates, to give an idea of its accuracy. The results are used as a guide to the accuracy of Aherne's approximation in more general situations. A summary of recommendations to the experimenter, as to when it is satisfactory to use Aherne's method, is given.
On the sub‐nanometre structure visible in high‐resolution dark‐field electron microscopy
Authors: Brakenhoff G. J.
Published: August 2011

In high‐resolution dark‐field microscopy thin carbon films present an appearance with many bright spots with sizes down to 0.3–0.5 nm which, by their presence, seriously interfere with the extraction of biological information. The nature of these spots has so far remained unexplained. It is shown that these spots are sharpest at an overfocus of about 275 nm with respect to the bright‐field focus condition. An explanation is presented here which accounts for both the focus difference and the otherwise inexplicable phenomenon of the small size of the spots. In the proposed model the bright spots are associated with small crystals present in the carbon film which give rise to Bragg reflection of electrons into the acceptance angle of the dark‐field geometry. Due to a constructive interference the Bragg‐reflected coherent electron wave fronts produce, behind the object, high‐intensity maxima with sizes equal to about × 1/5 the diameter of the scattering crystals. These maxima are now thought to produce the bright spots usually observed in dark‐field electron microscopy. The interference effect is illustrated with pictures of an optical analogue.
Quantitative analysis of mast cell structure
Authors: Helander Herbert F. , Bloom Gunnar D.
Published: August 2011

Fixed and embedded normal rat peritoneal mast cells were studied by light and electron microscopy, utilizing stereological methods to obtain quantitative data on their structure. The diameters of the mast cells and their nuclei averaged 10.9 and 5.8 μm respectively. The volume of the individual mast cell granule was estimated to 0.3 μm3. About 53% of the cytoplasmic volume was occupied by granules, and 2% by mitochondria. 11% of the cell volume was taken up by the nucleus. The average number of granules per cell was calculated to about 1020. Quantitative biochemical data on mast cells, extrapolated from the literature and applied to the calculated figures above, yield the following results with respect to mast granule contents‐heparin: 95 × 10−3 pg, histamine: 30 × 10−3 pg and 5‐hydroxytryptamine: 1.3 × 10−3 pg per mast cell granule.
High resolution in‐focus Lorentz electron microscopy
Authors: Podbrdský Josef
Published: August 2011

The Foucault in‐focus method for viewing magnetic domains in a conventional electron microscope has been modified. The main feature of our modification is to introduce an aperture below the intermediate lens and to use it for stopping out one part of the split central spot instead of the objective aperture. This arrangement substantially reduces the axial astigmatism due to the objective aperture and makes it possible to reach the point resolution 5–6 nm in both light and dark domains. The image resolution is limited by the small image magnification achieved using the three‐stage optical system of a Tesla BS 413 microscope.
Towards higher resolution in electron beam sensitive specimens of biological origin
Authors: Dobb M. G. , Murray R.
Published: August 2011

The resolution of structurally significant detail in electron micrographs of organic polymers is limited by damage to the specimen during electron irradiation. The factors affecting the kinetics of the degradation of characteristic high angle reflections in the electron diffraction patterns of Cellulose I and II have been studied in an attempt to determine quantitatively the conditions under which meaningful high resolution micrographs may be recorded.

In Cellulose I it was established that the decay of the 002 reflection during irradiation (in the range 0.6‐6.0 Am−2) is independent of dose‐rate. Moreover the meridional 040 and equatorial 002 reflections were found to decay at different rates. This latter finding indicates the importance of selecting the appropriate conditions for imaging a particular structural repeat in a specimen. Perhaps the most significant conclusion arising from this work is that specimen cooling in conjunction with low‐beam densities may be used to considerable advantage in obtaining meaningful higher resolution images than hitherto possible in beam‐sensitive materials.
Thermoelectric freeze‐drying
Authors: Bendet Irwin J. , Rizk Nabil I.
Published: August 2011

Freeze‐drying is a useful way to maintain the three‐dimensional morphology of biological materials for electron microscopy. The process is achieved simply by utilizing a commercially available thermoelectric unit within a standard vacuum evaporator.
Reproducibility of electron microscope magnifications with digital display of individual lens currents
Authors: Dunn Robert F. , Preiss Guenther W. B.
Published: August 2011

Quantitative measurements on electron micrographs with less than 10% error require precise calibration of all lenses contributing to the final image magnification. Calibration of the magnification to approximately 1.5% is easily attained by using simple statistical methods and a digital display milliampere meter capable of measuring the objective, intermediate and projector lens currents independently. The method detailed, readily adaptable to other electron microscopes, requires the projector lens current be held constant, with the magnification determined by varying the intermediate lens current and corrections made on the basis of calibrated objective lens current effect. The errors of magnification, approximately 1.5%, are the same range as the test grid variation which appears to be the limiting factor. Even with this limitation, magnifications have been determined reproducible to within less than 0.2% in daily use over a 6 month period.
A modified specimen stub for the scanning electron microscope
Authors: Peat C. J.
Published: August 2011

The standard ‘Stereoscan’ specimen stub has been modified to permit palynological acid‐maceration techniques to be performed under aseptic conditions. It is hoped that this adaptation will also be of use where contaminant‐free pure culture preparations are required, where delicate specimens are being treated, or where it is desirable to examine the precipitated products of chemical reactions.
A digital modification for beam current measurements in electron microscopy
Authors: Johansen B. V.
Published: August 2011

A digital microammeter with 0.1 μA sensitivity has been employed in the TEM beam current circuit to increase the accuracy to which the electron beam can be recorded and adjusted.
An energy filter for biological electron microscopy
Authors: Henkelman R. M. , Ottensmeyer F. P.
Published: August 2011

A prism‐mirror‐prism electron energy filter has been inserted into a fixed beam transmission electron microscope. The insertion of the filter has not degraded the spatial resolution of the microscope, while providing an energy resolution of 2.5 eV. The filter greatly reduces the chromatic aberration of the images, increasing resolution in dark field and contrast in bright field. Images of bacteriophage T4 and of polyoma virus indicate that thick unstained and unshadowed biological specimens can now be observed at high resolution in dark field. In addition, the increased contrast and definition observed in bright‐field images of conventional liver sections suggest that it should be possible to obtain sufficient contrast from stains containing atoms of lower atomic numbers than those employed at present.
Local beam heating in metallic electron microscope specimens
Authors: Kritzinger S. , Ronander E.
Published: August 2011

A very sensitive method is described to measure the local rise in the temperature of a metal specimen during investigation in the electron microscope. The method is based on the known temperature dependence of the climb rate of Frank dislocation loops in materials with relatively high stacking fault energy. The climb rate of loops subject to the influence of the condensed electron beam is compared to the corresponding rate for loops in an area of the same specimen which is remote from the observation spot. From the difference in the logarithms of these rates the amount of local beam heating is determined. For a typical Al‐1.5 wt% Mg specimen under typical normal working conditions an average local rise in temperature of approximately 6°C was determined.
Scanning electron microscopy of injection replicas of the chick embryo circulatory system
Authors: Dollinger Russell K. , Armstrong Peter B.
Published: August 2011

The injection replication procedure has been modified for study of the thin and very delicate blood vessels of young embryos. Batson's corrosion compound (a polyester resin) modified for rapid polymerization (20:3.0:0.25, monomer: catalyst: promoter) was effective in replicating even very small blood vessels without excessive distension. Since injection of plastic induced violent heart spasms with eventual expulsion of plastic from the ventricular lumen, contractility of the heart was inhibited by injection of a 2% (w/v) aqueous solution of KNO3 prior to injection with polyester resin. Following polymerization of the injected resin, the tissues were macerated and removed, leaving a solid three‐dimensional cast of the lumen of the circulatory system. The casts were photographed with the scanning electron microscope to produce accurate micrographs for study of the developmental anatomy of the circulatory system.
Caveat on the use of the Delesse principle of areal analysis for estimating component volume densities
Authors: Mayhew T. M. , Orive L.‐M. Cruz
Published: August 2011

In stereological work, component volume densities are estimated routinely by invoking the Delesse principle of areal analysis. This is true whether the morpho‐metric methods are based on the measurement of transectional areas, linear intercepts or point densities. Following our earlier consideration of the special case of a spherical component in a spherical containing volume, we here present a warning on the use of this fundamental principle. This report demonstrates that estimates of volume densities may be derived by application of two main formulations which are based on the areal analysis of ‘cubical’ and ‘spherical’ mathematical models. It is emphasized that these formulations of the Delesse relationship are not mathematically equivalent in all practical instances; failure to appreciate the correct practical circumstances in which each should be applied may lead therefore to the introduction of a statistical bias into the volume density data which are obtained. The conditions under which the formulations should be applied are stressed and clarified and some biological examples are provided. Whilst the problems are presented in a form which is aimed primarily at the biologist, they are also pertinent to the earth and materials scientists and to morphometrists in general.
A simple technique for examining fresh, frozen, biological specimens in the scanning electron microscope
Authors: Turner R. H. , Smith C. B.
Published: August 2011

A technique is described for the examination of frozen biological specimens on a modified stub, and a clamping device for examining freeze‐fractured specimens.
Simple mechanical device for orienting tissue blocks on the ultramicrotome*
Authors: Isler H.
Published: August 2011

A simple and inexpensive modification of the specimen holder of the Porter‐Blum model MT‐1 has been devised, which allows fine adjustments of tissue block orientation in both horizontal and vertical planes. It consists of an additional ring mounted on the existing locking ring and fitted with four radial screws which push the shaft of the chuck.
Observations on interphase boundary structure
Authors: Aaronson H. I.
Published: August 2011

A review is presented of experimental observations reported on the structure of interphase boundaries since 1968. Nearly all observed boundaries are of the partially or fully coherent type, and hence the principal structural features examined were misfit dislocations and ledges. Observations were drawn from studies of precipitation, spinodal decomposition, oriented overgrowths and eutectics. Interphase boundary structures were found to be little affected in the main by the type of reaction through which they were developed and were consistent with Van der Merwe theory and a theory of precipitate morphology. Observations of these structures have been considerably facilitated by the efforts of Weatherly and co‐workers to define the visibility and the optimum TEM viewing conditions of misfit dislocations and ledges. Important new observations on misfit dislocations made since 1968 include: misfit dislocation spacing in the Cr(Mo)/NiAl eutectic in good agreement with theoretical expectation because misfit dislocations are also glide dislocations and the interface plane is also the glide plane; misfit dislocations on θ′ Al‐Cu and η Al‐Au plates with a Burgers vector (a/2<100>) stable only at an interphase boundary; reduction of the interfacial energy of partially coherent boundaries on the same precipitates by dislocation interactions and rearrangements; reduction of interfacial energy of interfaces developed during spinodal decomposition through rotation of the interface itself from {100} to {110}; and misfit dislocation boundaries between f.c.c. (Cu‐rich) and b.c.c. (Cr) crystals made possible with the assistance of ‘structural ledges’. Growth ledges have now been observed in a number of alloy systems which have undergone precipitation from solid solution or eutectic solidification; they appear to be confirmed as a customary feature of migrating partially or fully coherent interphase boundaries. Much new experimental information has been obtained on the sources (exceedingly diverse), heights (usually appreciably higher than monatomic), spacings (irregular) and migration kinetics (diffusion‐controlled if their edges are disordered) of ledges. New observations continue to confirm the complexity of the processes through which misfit dislocations are acquired. The Ashby‐Johnson and the Brown‐Woolhouse theories of misfit dislocation nucleation or acquisition by spherical precipitates are in encouraging agreement with experiment.
Special grain boundaries in random polycrystalline aggregates
Authors: Warrington D. H.
Published: August 2011

The observation of different types of order present in grain boundaries is discussed. It is shown that, while the majority of boundaries in a cubic random polycrystalline aggregate may possess order characteristics of a ‘plane matching’ or CAD situation, very few boundaries will possess order characteristic of a CSL. Frequent observations of CSL or CAD order in the electron microscope indicate a non random polycrystalline aggregate.
Apparatus for annealing of electron microscope specimens under controlled atmospheres
Authors: Kritzinger S. , Monaci T. , Ronander E.
Published: August 2011

A detailed description is given of an annealing system in which transmission electron microscope specimens can be heat‐treated for known effective annealing times at accurately known constant temperatures. The apparatus includes facilities for annealing under corrosive atmospheres (such as chlorine) or vapours (such as bromine) at known pressures, and works in conjunction with an oil bath of which the temperature can be controlled to ±0.01°C. The thermal response of the specimen chamber at different annealing temperatures was determined by cine techniques. Typical results obtained with the system are presented.
Contrast enhancement in biological electron microscopy using two micrographs
Authors: Misell D. L. , Burge R. E.
Published: August 2011

A method is given for either dark‐ or bright‐field electron microscopy of thin biological specimens (e.g. thin sections) for enhancing the image arising from elastic scattering, relative to the composite image formed by inelastic scattering. The method requires two micrographs of a given field taken at two particular conditions of image defocus.
Scanning electron microscopy of rust haustoria
Authors: Pring R. J.
Published: August 2011

The three‐dimensional structure of rust haustoria has been studied by scanning electron microscopy (SEM). Rust infected leaves were fixed and embedded in Spurr's resin as for transmission electron microscopy (TEM). The cut surface of blocks containing embedded material was etched with sodium ethoxide and examined in the SEM.
The effect of intestinal distension and of section thickness on counts of epithelial nuclei in the rat small intestine
Authors: Clarke Rufus M.
Published: August 2011

A method is described for counting nuclei in wax‐embedded histological sections of epithelium. The counts are independent of section thickness over a wide range (4–10 μm).

Counts of nuclei were made in villi and crypts of rat small intestine fixed either collapsed or distended by a hydrostatic pressure equivalent to 350 mm of water. There was no significant difference between the counts of nuclei in collapsed or distended gut.

Distension reduced the absolute height of villi, and increased their absolute width at the base.

The implications of these findings for studies of the morphological basis of intestinal adaptation are discussed.
Estimation of section thickness, etc. by quantitative electron microscopy
Authors: Casley‐Smith J. R. , Crocker K. W. J.
Published: August 2011

Methods have been developed for the estimation of section thickness, and of the mass‐thicknesses, and hence the masses, of material embedded in sections. They are based on the current densities measured with a Faraday‐cage or on a new approximation for the relationship between exposure and optical density (OD) of the electron microscopical plate, which is valid for OD < 5. This relationship is quite distinct from the response to light, and also from an approximation for electrons which was only valid for OD < 1.2, and which was the basis for an earlier method.

The old methods and the two groups of new ones were tested, and also compared with the interference microscope. It was found that all but one of the new methods, in both groups, were homogeneous; the older methods and the interference microscope differed very significantly between themselves and with the homogeneous methods. The errors in the interference microscopical estimations were almost certainly due to the presence of embedded material in the sections, which could not be detected with the interference microscope because of its low resolution and the poor contrast in the thin sections. (A second set of experiments using only pure resin gave a good agreement between the homogeneous methods and the interference microscope.)

The orders of accuracy of the methods are quite high. A measurement repeated twelve to thirty‐five times will yield a value which has a 95% chance of being within 5% of the true value, while a single observation has a 95% chance of being within ∼ 25% of the true value with most methods, while some place it within ∼ 10%. Simplified, but less accurate, applications of the methods are also suggested.
The precise measurement of the thickness of ultrathin sections by a ‘re‐sectioned’ section technique
Authors: Yang Grace C. H. , Shea Stephen M.
Published: August 2011

The thickness of ultrathin tissue sections embedded in Epon‐Araldite and cut with a diamond knife was measured by re‐sectioning and electron microscopic examination of the section profiles. A secondary section mounted on a Formvar‐coated slot grid provided enough normally cut segments (seven to seventeen) for measurements giving a precise estimate of mean thickness, comparable to that obtainable by interference microscopy (±2.3% or less for grey to dark gold sections). The standard deviation of section thickness within sections was never more than 5 nm, corresponding to a coefficient of variation of 6.5% or less for sections more than 48 nm thick. This suggests that variation in section thickness, within sections, may be less than has been supposed, so that quantitative work may be based on thickness measurements made over a limited representative area. A silver interference colour was associated with sections 49–60 nm thick.
A low cost technique for producing high quality positive images from a SEM
Authors: Thurston E. L. , Sowers A. E. , Scott J. R.
Published: August 2011

Inexpensive positive prints can be made directly from a scanning electron microscope using standard print papers and image reversal of the photographic CRT.
The changing pattern of research in wood anatomy
Authors: Brazier J. D.
Published: August 2011

Research activity in wood anatomy since 1900 is reviewed with special reference to the pattern of development in (1) descriptive and comparative anatomy, (2) structure in relation to wood properties and (3) the influence of growth on wood structure. In the early decades of the century there was an emphasis on comparative anatomy, often as a contribution to developing the use of the tropical forest resource. At the same time, there was an increasing awareness that an understanding of the behaviour of wood was to be obtained from the study of its physical structure and chemical composition; particular attention has been given to elucidating the structure of the cell wall, at first by conventional optical microscopy and physical techniques and more recently by electron‐ and scanning electron‐microscopy. Studies of the interaction between growth and wood structure have attracted special interest in the post Second World War period and have been prompted by an awareness in many countries for a need to depend increasingly on managed forests as a source of timber and to produce such timbers at minimum cost compatible with acceptable technical performance.

Finally, in considering the future of wood anatomy, the view is expressed that if a continuing and more effective use is to be made of wood, then wood anatomy must have a future as it has a fundamental role in developing and applying the technology of wood. Particularly important is its role in contributing to the use of the world's timber resource, especially the many under‐utilized timbers in the developing countries, and the efficient production of plantation timber.
Interference microscopic studies on wood plastic and cell wall—liquid interactions in beech
Authors: Baas P.
Published: August 2011

A method is described to measure the content of methylmethacrylate‐polymer (poly‐MMA) in wood‐plastic composites and the influence of MMA on water and ethanol accessibility of beech wood fibre walls using interference microscopy. Although the S2‐layer of the fibre wall is capable of containing about 12% volume of plastic, the effect of treatment on ultimate water absorption of the cell wall is negligible. The ultimate absorption of ethanol is, however, completely reduced to zero. Increased dimensional stability of wood‐poly‐MMA composites is probably due to hindrance by the plastic in the lumina of the wood elements. The interference microscopic method is also shown to be suitable for determination of the fibre saturation point of cell wall areas.
Electron microscopy of critical point dried whole cultured cells
Authors: Buckley Ian K. , Porter Keith R.
Published: August 2011

To determine the overall fine structure of whole, unsectioned cells, cells from rat embryos were cultured on Formvar, glutaraldehyde/osmium‐fixed, transferred to grids, dehydrated, critical point dried, then examined by transmission electron microscopy at either 80 or 1000 kV. In contrast to air‐dried material, critical point dried cells revealed each component clearly and with excellent contrast. All normal cytoplasmic structures (including coated vesicles, polyribosomes, microtubules and other fine components) were readily identifiable. Extensive structures such as microtubules and the endoplasmic reticulum (which appear fragmented in sections) were well displayed. At 1000 kV the beam readily penetrated even the thick nuclear and perinuclear cell regions and produced exceptionally crisp images. The methods described provide a simplified approach to the study of overall cell fine structure.
Field ion microscopy of biomolecules
Authors: Machlin E. S. , Freilich A. , Agrawal D. C. , Burton J. J. , Briant C. L.
Published: August 2011

A new type of image, existing only at field strengths below the denaturation field strengths of molecules, has been discovered. This type of image has structure, is not symmetrical and thus differs from previously reported low field strength images. The possibility that macromolecules adsorbed on tip surfaces produce such structured images has been exhaustively investigated. The result is that no observation has been found which disproves this hypothesis and many tests conducted in such attempts yielded correlations consistent with this hypothesis. It is therefore concluded that it is highly probable that biomolecules produce structured images and that it is highly improbable that these correlations represent a chance event. On the other hand, these correlations may be due to some cause unknown to the authors; but we consider this possibility to be unlikely.

Some micrographs have been obtained which provide a reasonable basis for the hope that tertiary structure information may be derived from low field strength imaging of partially embedded biomolecules or of biomolecules that are resistant to field denaturation during imaging. Information may presently be obtained from analysis of low field strength ion micrographs about the size and shape of some biomolecules.
The effects of hypobaric atmospheres on living cells in layers of thin media and implications for electron microscopy
Authors: Lyon Norman C. , Kirsh Richard L. , Parsons Donald F.
Published: August 2011

At present, the only possibility for improved resolution of intracellular movement appears to be electron microscopy using a hydration chamber (EMC) at reduced gas pressures with thinned medium around the cells. The environmental constraints of examining cells under such conditions were examined in the absence of ionizing radiation by using an EMC‐analogue fitted to a light microscope. White blood cells and baby hamster kidney cells were examined. A 50% survival pressure value, for hypobaric atmospheres, was determined for these cells. Morphological changes of the hypobarically‐exposed cells are described.
A transmission electron microscope study of the effects of ion etching on cells
Authors: Frisch B. , Lewis S. M. , Stuart P. R. , Osborn J. S.
Published: August 2011

The effects of ion etching on blood cells have previously been studied by scanning electron microscopy. This present study by transmission electron microscopy was undertaken to evaluate the effects of the etching process on the cells. Critical point dried preparations were made, etched and subsequently processed and embedded in Araldite. Examination of thin sections of erythrocytes revealed disintegration of the plasma membrane; the residual membrane destruction products formed the tips of cones produced by long etching times. The effect of etching varied in erythrocytes in the same preparation. Nucleated cells showed a similar disintegration of the plasma membrane, but membranes of mitochondria, granules, vesicles and vacuoles did not exhibit effects of etching comparable to those of the plasma membranes. After treatment with a number of different fixatives, erythrocytes on carbon‐coated copper grids were also etched and examined directly in a high voltage electron microscope at 1 MV. The effects were comparable to those seen in thin sections. To study the etch rates of biological materials, the resonant frequencies of quartz crystals were measured after application of thin films of albumen and cholesterol and again after these had been etched. The ratio of the frequency changes indicated that the etch rate of albumen was approximately 2.5 times that of cholesterol.

The results are discussed in the light of theories of the mechanisms involved in ion etching.
Graphite crystal film preparation by cleavage
Authors: Hines R. L.
Published: August 2011

Graphite films which are free of adhesive contamination are prepared by glueing a crystal to an adhesive coated grid and then cleaving away the top graphite layers with adhesive tape. The final graphite films in the centres of the grid openings do not come into contact with the adhesive at any time during the preparation process. Graphite crystal films a few tens of nanometres or less in thickness with large areas of uniform thickness are easily produced.
Analysis of droplets from iso‐atomic solutions as a means of calibrating a transmission electron analytical microscope (TEAM)
Authors: Morgan A. J. , Davies T. W. , Erasmus D. A.
Published: August 2011

This paper describes a spraying method of producing iso‐atomic droplets (≅3 μm diameter) of uniform size, distribution and chemical composition. These droplets were used to calibrate a TEAM system operated under given conditions, so that the relative sensitivity of the instrumentation for the elements Na, Mg, P, S, (Cl), K, Ca and Co (‘overall sensitivity factors’) could be determined. These factors (15, 40, 83, 90, (43), 104, 109, 100% respectively) were used to convert observed X‐ray intensity ratios from standard droplets to relative amounts of elements with a fair degree of accuracy (error generally less than ± 10%). It was proposed that the sampling and quantification methods could be applied for the absolute quantitative bulk‐analysis of fluids and tissues (after solubilization) with an introduced reference element, e.g. cobalt, and potentially to the study of relative elemental ratios in fluid microvolumes and in biological thin sections.
Thin polymer films as non‐charging surfaces for scanning electron microscopy
Authors: Pease R. W. , Bailey J. F.
Published: August 2011

Films of formvar, 1.2–20.0 nm in thickness, collodion and a 60/40 styrene‐vinylpyridine copolymer (precipitated from solution) have been found to provide a noncharging layer on the surface of several types of specimens, including loose, or fibrous specimens. No electron build up was observed in most of the specimens when examined with a scanning beam of up to 30 kv for unlimited periods of time.
The avian erythrocyte: a study of fixation for electron microscopy
Authors: Brown J. N.
Published: August 2011

The quality of ultrastructural preservation of the avian erythrocyte achieved using various fixation techniques is evaluated. Different combinations of initial fixatives, buffers and post‐fixation procedures were tested as well as variations in fixative osmolarity, pH and temperature. Of the commonly used initial fixatives (glutaraldehyde, acrolein and formaldehyde), 2% glutaraldehyde, alone in a slightly hypertonic buffer containing divalent ions, produced optimum erythrocyte preservation. The osmolarity was balanced using a non‐electrolyte such as sucrose. The addition of 12% hexylene glycol to the buffer solutions also improves erythrocyte preservation, as evidenced by the increased stability of the marginal microtubules, microfilaments and proteinaceous material.

The use of Spurr low‐viscosity epoxy resin enables the cells to be collected using low gravitational centrifugation.
Coating sections for electron microscopic autoradiography: a stripping technique using liquid emulsion
Authors: Burry Richard W. , Lasher Robert S.
Published: August 2011

A coating technique for electron microscope autoradiography is described which combines the advantage of forming an emulsion film by a dipping method with the ease of coating sections already on grids. Sections are coated so that a formvar support film separates the section and the emulsion crystals. This intermediate layer of formvar ensures a random distribution of the emulsion crystals. Using light gold sections, Ilford L‐4 emulsion and Microdol‐X development, the resolution of this technique, as determined by the half distance method, was 150 nm. The additional layer of formvar slightly reduced the image quality with biological samples in the electron microscope. This technique has a minimal loss of resolution and image quality for moderate resolution electron microscope autoradiography.
A new method for comparative light and electron microscopic studies of individual cells, selected in the living state
Authors: van Ewijk W. , Hösli P.
Published: August 2011

A method is described which permits comparative light and electronmicroscopic studies of cell cultures, cell spreads or single selected cells which have been kept in the Plastic Film Dish (PFD). The PFD is a versatile large surface tissue culture chamber which, for electron microscopy, is mounted with a transparent FEP‐Teflon film bottom. Cells are observed, selected and marked on the PFD‐bottom with a high power inverted light microscope. The cells are fixed and dehydrated with a semi‐automatic device while they are still in situ in the PFD. During the preparation steps for electron microscopy the topographical relationship between individual cells and between cells and cell support is accurately retained. After embedding and polymerization the Teflon film is easily peeled off the polymerized Epon, leaving a replica of the mark around the selected cell. This permits relocation of the selected cells for ultrathin sectioning in a plane plan‐parallel to the original cell support. To enable orientated sectioning of selected cells in a plane perpendicular to the cell support, cells are tagged with Letraset‐letters after original embedding and polymerization. Subsequently the re‐embedded polymerized specimens are orientated in the microtome in a position which permits controlled thin sectioning of the tagged cells in the previously selected plane.
A comparative study in the transmission electron microscope and scanning electron microscope of intracellular structures in sheep heart muscle cells
Authors: Myklebust Reidar , Dalen Helge , Saetersdal Thv. Selmer
Published: August 2011

The internal cellular structures of the sheep ventricular myocardium have been comparatively studied in the transmission electron microscope (TEM) and in the scanning electron microscope (SEM). For TEM studies the tissue was prepared according to standard methods. Thick sections (10 μm) of paraffin embedded material were, after they had been deparaffinized in toluene, critical point dried, coated with gold and examined in the SEM. The comparative TEM and SEM investigations revealed very good correspondence, and it is evident that the described preparation procedure for SEM has preserved the fine structures of myofibrils, mitochondria, T‐Tubules and sarcoplasmic reticulum in an excellent life‐like pattern. Of special interest was the three‐dimensional demonstration of triads and of circumferentially arranged T‐tubules.
Ice crystal growth in skeletal muscle fibres
Authors: Sjöström Michael
Published: August 2011

Ice crystal growth was studied in rapidly frozen skeletal muscle fibres which were treated with cryo‐protective additives (glycerol, DMSO, sucrose) or which were untreated. Freeze cleaving and etching was the basic method, with conventional plastic embedding and cryo‐ultramicrotomy as complementary techniques.

Extensive crystal growth occurred during freezing in all unprotected fibres. Just below the fibre surface the crystals were numerous but small, while deeper in the fibre they were fewer but larger. The deeper within the specimen a fibre was located, the larger, in general, was the crystal size. The crystal volume density was about 55%, irrespective of crystal size. Ice recrystallization was practically absent at the temperature normally used in cryo‐sectioning (–70°C). Anti‐freeze treatment eliminated crystal growth. If the anti‐freeze agents were used in non‐toxic concentrations, however, their effect on crystal growth was very limited. ‘Dry’‐cut, freeze‐dried ultra‐thin cryosections of protected and unprotected fibres confirmed these observations, while sections obtained by ‘wet’ cryo‐cutting showed no apparent signs of crystal growth. In plastic sections of frozen and thawed fibres a previous occurrence of crystals was only slightly indicated.

In interpreting the ultrastructure in ‘wet’‐cut cryo‐sections of unprotected frozen mucle fibres, the distorting effects of ice crystals through mechanical compression and alterations in sectioning conditions, must be taken into consideration. Crystal growth also strongly limits the possibilities of using ‘dry’‐cut sections of untreated frozen tissue for analytical electron microscopy; only the most superficial parts of the fibres seem to be suitable for microanalysis.
The relationship of plastic deformation in freeze‐etching to the orientation of a protein particle
Authors: Willison J. H. M.
Published: August 2011

Freeze‐fracturing of face‐centred, cubically packed, intracellular crystals of fraction 1 protein result in two distinct fracture responses of the constituent particles, according to their orientation relative to the plane of fracture. If a square‐packed plane is revealed, fracture occurs either between particles or the particles plastically deform. Conversely, if a hexagonally‐packed plane is revealed, fracture occurs either between particles or cleanly at internal planes of the particles, without any plastic deformation. It is proposed that this information may be of value in determining the arrangement of the axes of the covalently bound polypeptide protomer chains which constitute the oligomer.
The effect of gas on the irradiation of aluminium inside a high voltage electron microscope
Authors: Mayer R. M. , Stobbs W. M. , Ward P. R.
Published: August 2011

An environmental cell was used in the high voltage electron microscope to observe the formation of radiation damage in aluminium and dilute aluminium alloys in the presence of gas atmospheres of hydrogen, helium and air. The types of defect produced under such conditions are classified and it is shown that the characteristic of electron irradiation in the presence of a gas is the promotion of void nucleation. The implication of this observation with regard to the design of reactor materials is discussed.
A multipurpose specimen‐carrier for handling small biological objects through critical point drying
Authors: Rostgaard J. , Christensen P.
Published: August 2011

A specimen‐carrier for safely handling, protecting and drying minute biological specimens down to 1·0 μm in size during the various steps of the critical point drying procedure is described. Free, unattached cells or subcellular fragments can be processed without loss and without risk of unintentional air‐drying.
Quantitative analysis of micrographs by computer graphics*
Authors: Dunn Robert F. , O'Leary Dennis P. , Kumley Warren E.
Published: August 2011

A computer‐aided graphical analysis system is presented which can be used to quantify several types of information from micrographs of cross‐sectioned peripheral nerves. A simple input consisting of eight points, corresponding to two diameters of each axon and two for each axon plus myelin, is used to compute statistical and numerical estimates of these diameters, the myelin thickness being expressed as a function of axon diameter, and both the spatial position and distribution of nerve fibres within the bundle. The computer programs presented and summarized here describe the procedure for digitizing the input data and the subsequent computations for editing and analysis. The general applicability of this approach for automated analyses of other anatomical areas is also presented.