bluuebunny/crossref_metadata_2025 huggingface dataset:
High voltage electron microscopy of wet whole cells
Authors: Parsons D. F. , Uydess I. , Matricardi V. R.
Published: August 2011

Factors affecting the visibility of cell cytoplasmic structures and cell surface projections have been evaluated for examination of whole wet, unstained and unfixed cell preparations in the hydration chamber of a high voltage microscope.

It was found that the thickness of the cells and that of the surrounding water layer were the most important factors affecting contrast and resolution of structures. One technique (surface spreading) flattened nuclei enough to see internal nuclear structure. Some washing and fixing (glutaraldehyde) methods caused regions of the grid of cultured cells to become hydrophobic with consequent improvement in contrast and resolution in these areas. Optimization of these factors appears feasible.

The effects of cell freshness, blurring due to cell structure, vibration and Brownian movement, electron radiation and heat damage, microscope image mode, and photographic emulsion resolution are also discussed.

Cell movements (e.g. cytoplasmic streaming) have not been observed to date, the possible reasons being radiation damage, cell bursting at lowered pressure, oxygen lack and concentration of metabolites on the grid surface.
Rapid freezing and electron microscopy for the arrest of physiological processes
Authors: Van Harreveld A. , Trubatch Janett , Steiner Jana
Published: August 2011

An apparatus for the rapid freezing of tissue is described, which can be used for the electron microscopy of arrested physiological processes. The material is frozen by bringing it in contact with a silver surface cooled to liquid nitrogen temperature at reduced pressure. The freezing surface is protected from condensation of moisture and gases from the air by a flow of helium gas. The cooling of the specimen during its descent through the cold helium is not large enough to interfere with physiological processes. Freezing occurs very rapidly in the surface but is retarded to about 8 msec at a depth of 10 μm. The apparatus was used to freeze frog muscle during contraction.
Current developments in high voltage electron microscopy
Authors: Cosslett V. E.
Published: August 2011

In respect of instrument design two main developments are taking place in high voltage electron microscopy: towards even higher operating voltages (3–5 MV) and towards higher resolving power at moderate voltages (250–600 kV). Applications of existing instruments (650 kV‐1.2 MV) are still primarily in metallurgy, especially for radiation damage studies, but their usefulness for biological research is now being actively explored. Microchambers have been developed for observing specimens, both metallurgical and biological, in a controlled gaseous or liquid environment. The prospects for observing living material, except at low magnifications, remain very doubtful on account of ionization effects, but informative work with wet specimens should be possible.
Scanning transmission electron microscopy*
Authors: Crewe Albert V.
Published: August 2011

The scanning transmission electron microscope is of quite recent origin, and it is only in the last few years that it has been shown that this instrument is capable of giving the same high resolution as the conventional electron microscope. In this article we examine the conditions necessary for the achievement of high resolution and also the various modes of contrast which can be obtained from this instrument. Finally, we suggest other ways in which the microscope can be used in future investigations.
Effect of fixatives on fracture plane in red blood cells
Authors: Nermut M. V. , WARD Barbara J.
Published: August 2011

The effect of various fixatives on the path of the fracture plane during freeze‐fracturing was studied in red blood cells. In unfixed cells the fracture plane ran between the leaflets of the plasma membrane (membrane‐fractured cells) in 66% of the cells and across the cells (cross‐fractured cells) in 34%. Formaldehyde fixation greatly increased the proportion of cross‐fractured cells (up to 80%) and osmium tetroxide acted in a similar manner (up to 90% cross‐fractured cells). With glutaraldehyde fixation, small, smooth patches of cross‐linked material were often seen on the convex (A) fracture faces. Holes were found on the corresponding concave (B) fracture faces. Uranyl acetate had no effect on the fracture plane or distribution of particles. Thus osmium and formaldehyde might be a useful means of altering the fracture plane of membranes (e.g. in bacteria or enveloped viruses).
A simple video method for the quantification of microscopic objects
Authors: Dvorak James A. , Schuette William H. , White‐House Willard C.
Published: August 2011

The design and operation of a simple, semi‐automatic video system for the analysis of geometric parameters of microscopic specimens is described. The system consists of standard video equipment and a custom built Electronic Integrator. The video signal from a camera attached to a microscope is mixed with the video signal from a second camera focused on a drawing board. A contour outline of the specimen to be analysed is drawn with the aid of a video monitor display of the combined images. The contour image is passed into the Electronic Integrator and analysed automatically. Logic circuitry in the Electronic Integrator permits analysis of complex contours independent of their orientation in the video raster. The area or volume of complex, overlapping specimens with restricted grey scale range can be rapidly analysed. The Electronic Integrator also is suitable for densitometric and specimen motion analyses.
An experimental study of coincidence grain boundary structure using displacement fringes
Authors: Pond R. C. , Smith D. A. , Clark W. A. T.
Published: August 2011

This paper describes how a transmission electron microscope may be used to study rigid body displacements between coincidence related grains. Computer calculations have predicted that such displacements reduce grain boundary internal energy in metals by relieving atomic over‐crowding. Displacements are revealed as fringe patterns by a Bloch wave interference mechanism resembling that which gives rise to stacking fault fringes. The sensitivity of the technique in detecting very small displacements and its potential applications are discussed.
Techniques for the observation of grain boundaries in an austenitic stainless steel
Authors: Howell P. R. , Jones A. R. , Ralph B.
Published: August 2011

This paper discusses methods of analysing grain boundary structure in a commercial alloy system using transmission electron microscopy of thin foils. The results illustrate how the fine scale structure of grain boundaries may be analysed by employing weak beam imaging techniques and grain boundary diffraction effects.
The annealing of dislocations in high angle grain boundaries and structural models
Authors: Pumphrey P. H. , Gleiter H.
Published: August 2011

Hot stage electron microscopy is used to study the annealing behaviour of lattice dislocations in high angle grain boundaries in nickel. The observations show that most boundaries can incorporate dislocations by increasing their core widths or splitting into partials with small Burgers vectors. The implications for models of grain boundary structure are discussed.
An observation of periodicity in grain boundaries
Authors: Bolin P. L. , Bayuzick R. J. , Ranganathan B. N.
Published: August 2011

Field ion microscopy and computer graphics techniques have been utilized in studying the topography of a grain boundary in a W‐1wt%ThO2 specimen. Perspective plots and Stereographic Pole Plots of the surface were obtained. An examination of the perspective plots of the boundary surface in conjunction with the Stereographic Pole Plot reveals a strong tendency towards periodicity in the grain boundary. Although no definite wavelength is noticed, an overall tendency towards periodicity is evident. Further the Stereographic Pole Plot indicates the nature of the inclinations in the grain boundary surface.
The topographical structure of grain boundaries in tungsten
Authors: Howell P. R. , Ralph B.
Published: August 2011

This paper discusses the observation of a variety of topographical defects in grain boundaries in tungsten as a function of thermomechanical treatment. It is shown that, for both cold worked and crept specimen material, the boundary topography is highly complex, whereas for secondary recrystallized specimen materials the boundaries approximate to that expected for an ‘equilibrium’ configuration. However, no evidence for any period step structure was observed in this specimen material although, in this and all specimen states, grain boundary dislocations were frequently observed.
The quantitative analysis of thin specimens
Authors: Cliff G. , Lorimer G. W.
Published: August 2011

Results are reported concerning the use of an energy dispersive X‐ray detector to carry out the analysis of thin foils in the electron microscope. The combination of a thin specimen and the extreme stability of the energy dispersive X‐ray detector enables the experimental determination of a calibration curve of X‐ray production—detection efficiency vs characteristic X‐ray energy. Quantitative analysis can be carried out using the calibration curve without reference to standards at the time of analysis.
Radiation damage in stained catalase at low temperature
Authors: Glaeser Robert M. , Hobbs Linn W.
Published: August 2011

Radiation damage, which occurs in the beam of the electron microscope, has been studied in uranyl acetate stained catalase crystals. Damage is observed in terms of the disappearance of higher orders of the electron diffraction pattern. In this study it has been found that the damage at very low specimen temperatures proceeds both more rapidly and to a greater final degree than is the case at room temperature.
Freeze‐fracturing and freeze‐etching of cardiac myosin filaments
Authors: Rayns David G.
Published: August 2011

Myofilament structure was studied in freeze‐etch replicas of unfixed, glycerinated beef cardiac muscle. The information which is revealed depends upon the direction of metal shadowing in relation to the filament axis. Shadows oblique to this axis reveal that the outer surface of a longitudinal half of a thick filament comprises three, sometimes four, rows of myosin molecules. These molecules are generally assembled in a braided manner with both left and right‐handed helical components. Occasionally a more parallel arrangement is seen; this may represent a split filament. Shadows parallel to the myofilament axis reveal cross‐bridges linking thick and thin filaments. These bridges are readily detectable by optical diffraction techniques, giving an axial bridge spacing of approximately 40 nm. In unetched preparations cross bridges appear as vertical rows of beads. In all replicas the effects of plastic deformation of proteins must be considered.
X‐ray microradiography in the scanning electron microscope or microanalyser
Authors: Pugh D. J. , West P. D.
Published: August 2011

A technique is described which enables microradiographic examination to be carried out in a scanning electron microscope (SEM) or X‐ray microanalyser. Comparison can readily be made between the radiographic image, a conventional scanning electron image or X‐ray image. A wide range of materials have been examined in a Cambridge Scientific Instruments Microanalyser Mark 1 and a Stereoscan S1 scanning electron microscope and a resolution of 1 μm has been consistently achieved.
A technique for processing mucous coated marine invertebrate spermatozoa for scanning electron microscopy
Authors: Atwood D. G. , Crawford B. J. , Braybrook G. D.
Published: August 2011

A technique for preparing heavily mucous coated marine invertebrate spermatozoa for scanning electron microscopy (SEM) is described. This technique involves washing in 1500 NF units/ml hyaluronidase in millipored sea water to remove mucus, followed by fixation in glutaraldehyde and osmium tetroxide. Following primary fixation, spermatozoa are enclosed in Nuclepore membrane bags positioned within Teflon specimen capsules allowing them to be processed and critical point dried without excessive mechanical damage or loss.
The pore arrangement in the emu (Dromaius novæhollandiæ) eggshell as shown by plastic models
Authors: Board R. G. , Tullett S. G.
Published: August 2011

Pores arising in the cone layer merge with a plexus of tubules running just under and parallel to the outer surface of the emu eggshell. The outer surface of the shell is irregular due to dark green crystalline material arranged as flat domes. The plexus of tubules vent to the ambient environment via short pores opening in the valleys between these domes.
A technique for preparing human dermal and scar specimens for scanning electron microscopy
Authors: Sommerlad B. C. , Creasey J. M.
Published: August 2011

The aims in a current study of dermis and scar tissue using the scanning electron microscope are:

to maintain the orientation of the specimen

to preserve the in vivo architecture, and

to expose a satisfactory surface.

A technique which best fulfils these requirements involves glutaraldehyde fixation of a splinted specimen, freeze‐fracturing using a modified pair of pliers, freeze‐drying, incubation in a buffered saline solution of hyaluronidase and freeze‐drying again after washing.

Consistently satisfactory specimens have been obtained, which provide information about fibre architecture and cell distribution.
A magnetic holder for low angle rotary shadowing of electron microscrope grids
Authors: Watt P. Ridgway , Macdonald A. C.
Published: August 2011

Magnetic retention of nickel grids is incorporated into the design of a rotary shadowing turret. Other uses of the principle are suggested.
Timber—a review of the structure‐mechanical property relationship
Authors: Dinwoodie J. M.
Published: August 2011

Following a brief introduction concerned with present consumption and future prospects of timber and timber products the principal structure‐property relationships of this low density, cellular, polymeric composite are reviewed and discussed. Structure is examined at four levels of magnitude—macroscopic, microscopic, sub‐microscopic and chemical—and the various models used to interpret its composite nature are described.

The dimensional instability of timber and loss of strength on wetting are discussed in terms of its fine structure. At low levels of stressing, and for short periods of time, timber can be treated as an elastic material, but at higher stresses and prolonged periods, especially with alternating humidity, timber behaves as a linear orthotropic viscoelastic material; the various factors influencing the elastic constants and the relationship of creep to fine structure are discussed.

The anisotropy of wood is related to cell arrangement and microfibrillar orientation: strength and its variability are discussed in terms of structure at all four levels. Comparison of the strength of timber with that of other constructional materials especially on a weight basis shows timber in a very good light; the combination of high stiffness and high toughness is unique. Recent models using three‐dimensional anisotropic elastic analysis to understand strength and deformation of timber are described. The morphology of fracture under different forms of stressing is illustrated.
Structural components influencing the permeability of ponded and unponded Sitka spruce*
Authors: Bolton A. J. , Petty J. A.
Published: August 2011

Study of the gaseous permeability of wood stored in ponds to promote bacterial decomposition of the bordered pit membranes has shown that the pit aperture/pit cavity contributes to the total resistance to flow of liquids through both ponded and unponded wood. In ponded wood the contributions of the pit apertures/pit cavities ranged between 5% and 46% of the total resistance, the tracheid lumina making up the remaining 96–54%. This large variation is attributed to the presence of different proportions of earlywood and latewood in specimens tested. In air‐dried unponded wood, however, the pit membrane pores contribute an average of 81% of the total resistance to liquid flow, the tracheid lumina an average of 16%, and the pit aperture an average of only 3%. An implication of these results is that previously used analytical techniques for the determination of the radius and number of conducting flow paths in wood, based on the assumption that only two structural components offer resistance to flow, are not wholly satisfactory.
Wood substance as a water‐reactive fibre‐reinforced composite
Authors: Cave I. D.
Published: August 2011

A constitutive relation for an elastic fibre composite material consisting of an inert fibrous phase embedded in a water‐reactive matrix has been derived. The relation is determined in terms of the overall stiffness of the composite, the volume proportion of the matrix, and stiffness and sorption functions of the matrix that are dependent on moisture content. The proposed model of the matrix is believed to be appropriate to wood substance. The constitutive relation is, therefore, applicable to a basic element of wood substance and can be applied to models of wood structure to calculate mechanical properties such as shrinkage, moisture‐induced creep and other moisture‐related properties.
Adsorption of DNA molecules to different support films
Authors: Sogo J. M. , Portmann R. , Kaufmann P. , Roller Th.
Published: August 2011

Protein‐free adsorption of the DNA of the Escherichia coli bacteriophage T7 to carbon, collodion, aluminium‐beryllium and aluminium films was studied. It was found that the appearance of DNA strands depended greatly upon the kind of support film used. Direct adsorption of DNA to aluminium‐beryllium or aluminium films yielded specimens with ‘thin and long’ and ‘thick and short’ regions along the strand. Well extended, uncoiled and unaggregated DNA molecules were obtained only when DNA was adsorbed to carbon, collodion or mica in the presence of intercalating dyes such as ethidium bromide. Adsorption properties of the different films are well correlated with their surface charge. Aluminium‐beryllium films carry a strong positive surface charge, aluminium films a weak positive charge and carbon films a weak negative charge.

It is suggested that for the preparation of specimens by spontaneous adsorption of well extended and unaggregated strands it is necessary that the DNA molecule is stiffened by a ligand such as an intercalating dye, and that the charge on the surface of the support film is opposite to the charge of the macromolecule.
A freeze‐fracture replication apparatus for biological specimens*
Authors: Stolinski C.
Published: August 2011

A freeze‐fracture apparatus of original design has been constructed which can be fitted onto a standard vacuum evaporator unit. In it, cell suspensions and organized tissue may be processed by inserting a sample into a cylindrical holder. By leaving a small part of the tissue protruding from the holder, pre‐selected and aligned portions of the specimen can subsequently be revealed by fracture under vacuum. After rapid freezing, the specimen remains firmly attached to the inner wall of the sample holder, preventing its possible loss during fracturing. A mechanism, in the form of a double‐sided converging wedge, which is operated from outside the vacuum chamber, is used to produce a fracture in the specimen. The device gently induces a fracture in the desired part of the tissue and lifts the protruding part of the specimen out of the way. In this way, reasonably flat fracture faces are produced for subsequent replication. As the fracturing mechanism comes into contact only with the outer edges of the specimen, damage and contamination liable to occur when the entire specimen is traversed by a blade, is avoided. In addition the specimen stage is surrounded by a cold metal shroud which acts as an efficient trap for contaminants. In this way, favourable vacuum conditions are produced in the vicinity of the specimen. Such effective enclosing of the specimen also facilitates controlled sublimation of the sample.
Abel type integral equations in stereology. II. Computational methods of solution and the random spheres approximation
Authors: Anderssen R. S. , Jakeman A. J.
Published: August 2011

As mentioned in Part I of this paper, Part II is mainly concerned with the construction of stable computational methods for the solution of integral equations of Abel type which occur in stereology. However, in order to develop a rationale for the types of methods which we shall propose, it is first necessary to review the different types of methods which have been suggested to date in the stereological literature. This is done in section 2. From the review, we conclude that the construction of stable methods can be based on the use of spectral differentiation and product integration to evaluate appropriate inversion formulae, when they are known. Using the Random Spheres Model as exemplification, we examine the nature of such methods in section 3. The potential of the proposed methods is illustrated in section 4 by examining the reliability of the random spheres approximation—an unsolved problem in stereology proposed by Moran (1972). We conclude from this examination that the random spheres approximation is quite reliable for particles which approximate spheres.
Redundancy of washing in the preparation of biological specimens for transmission electron microscopy
Authors: Ockleford C. D.
Published: August 2011

A marine unicellular organism, human trophoblast tissue and cultured trophoblast cells of human origin have been satisfactorily preserved for electron microscopy without resort to washing either before dehydration or between different stages of fixation.

The time required to fix and dehydrate a specimen using this method is 55 min.
Preparation of vascular endothelium for scanning electron microscopy: a comparison of the effects of perfusion and immersion fixation
Authors: Gertz S. David , Rennels Marshall L. , Forbes Michael S. , Nelson Erland
Published: August 2011

A comparison of currently used methods of tissue fixation for scanning electron microscopic study of vascular endothelium revealed that in situ fixation by intravascular perfusion is superior to immersion for the preservation of endothelial surface morphology.
High resolution electron microscope study of lattice images in biological apatites
Authors: Spector M.
Published: August 2011

Lattice (Fourier) images of crystallites in human bone and teeth, and calcified atherosclerotic plaque were studied using high resolution transmission electron microscope techniques. The lattice images observed in the normal and diseased calcified tissue were compared with the images of synthetic hydroxyapatite crystallites.
Identification of nerve fibres in the scanning electron microscope
Authors: Sætersdal Thorvald Selmer , Myklebust Reidar
Published: August 2011

The use of silver as a ‘stain’ for nerve fibres in scanning electron microscopy (SEM) preparations has been investigated. Samples of cardiac tissues were treated according to the Bielschovsky silver impregnation method. Following embedding in paraffin, successive sections were selected for light microscopy and for SEM studies, respectively. The silver impregnated fibres, when examined in SEM preparations, appeared nearly white against a greyish background of cardiac tissue. They were therefore easy to localize even at a low magnification. These nerve fibres were identified in the same tissue, but different blocks by means of transmission electron microscopy (TEM) studies and by fluoroescence microscopy.
Handling and staining epoxy resin sections for light microscopy
Authors: Roberts I. M. , Hutcheson A. M.
Published: August 2011

Epoxy resin sections 0.1‐1.0 μm thick of specimens embedded for electron microscopy, were collected from the ultramicrotome using strips of cover slip, and, after drying on a hot plate, were bulk stained in specially made troughs. After treatment with periodic acid, the sections were stained first in basic fuchsin at 70°C and then in alkaline methylene blue at room temperature. The handling technique allows accurate collection of serial sections without interrupting the sectioning process, and the stain combination is suitable for different specimens in different epoxy resins and is unaffected by storage for more than 1 year.
The preparation of human articular cartilage for scanning electron microscopy
Authors: Cameron C. H. S. , Gardner D. L. , Longmore R. B.
Published: August 2011

This paper compares sixteen preparative techniques thought to be of advantage in the study by scanning electron microscopy (SEM) of human articular cartilage surfaces. The adequacy of surface preservation obtained with the techniques, was judged subjectively, first, by the reproducibility of secondary electron images of normal cartilage, and second, by comparing the results with those obtained by reflected light microscopy of the fresh unfixed cartilage surface over a magnification range of × 20 – × 240.

Adequate surface preservation was confirmed when cartilage surfaces had been dehydrated through ethanol to propylene oxide and vacuum dried; dehydrated through amyl acetate and quenched in Freon before freeze‐drying; dehydrated and passed through amyl acetate at low temperature before freeze drying.

Valuable information can be obtained from different specimens by varying the technique of preparation. At different ages, different surface features are best preserved. In a systematic study it has been found essential to adopt a uniform preparative method and to control the results by reflected light microscopy. Even with the most perfect preparation, the surface appearances cannot be identical with those that function under load in vivo.
High resolution microanalysis in materials science using electron energy loss measurements
Authors: Williams D. B. , Edington J. W.
Published: August 2011

The physical basis of microanalysis using measurements of electron energy losses associated with atom ionization or plasmon excitation in thin electron microscope specimens is explained in a simple manner. In addition the equipment used to resolve both the high and low energy regions of the loss electron spectrum is described. It is shown that ionization loss analysis is still in its infancy, but plasmon loss analysis has now been providing quantitative microanalytical data on light metal alloys for 8 years. The results obtained from both techniques and their application to specific metallurgical problems are reviewed. Conclusions are drawn concerning the future use of these techniques in high resolution microanalysis.
The identification of asbestos
Authors: Champness P. E. , Cliff G. , Lorimer G. W.
Published: August 2011

Techniques are described for identifying and distinguishing between the six varieties of asbestos. When the fibres are large and numerous, as is the case for insulation materials, simple optical or X‐ray methods suffice. For environmental samples one must normally resort to electron microscopic techniques for a positive identification. When asbestiform minerals are to be distinguished from other fibrous silicates it is often necessary to use both electron diffraction and X‐ray spectrometry.
Potential hazards of uranium and its compounds in electron microscopy: A brief review
Authors: Darley James J. , Ezoe Hisanori
Published: August 2011

Uranium and its compounds are radioactive and highly toxic. Although well documented in the specialized literature the potential hazards are little known among microscopists. Labelling of these compounds does not indicate potential hazards sufficiently.
Molecular hybridization of RNA and DNA in situ: visualization at the electron microscope level
Authors: Jacob J. , Moar M. H. , Gillies Katherine , Macleod D. , Jones K. W.
Published: August 2011

Electron microscopic visualization of molecular hybrids formed in situ is feasible at the present time. It can be accomplished by two alternative approaches. In one, the in situ hybridization is carried out on ultrathin sections of target embedded in glycol methacrylate. In the other, whole cells are used for hybridization and they are subsequently prepared for electron microscopy. The choice of the method to be adopted depends on the type of target tissue. When there is a choice, the second approach seems preferable. Some of the important technical steps in the hybridization procedure, such as DNA denaturation in ultrathin sections, have been discussed and attention has been drawn to practical problems that may arise during the preparatory steps. Our light microscope experiments demonstrate that preparations made after glutaraldehyde fixation have a lower hybridization efficiency than those fixed with 3: 1 methanol‐acetic acid. Attempts are therefore being made to explore the possibility of using methanol‐acetic acid for electron microscope in situ hybridization. First results of straightforward fixation show that the preservation of nuclear structure may be fairly satisfactory for the purpose. However, the cumulative effects of subsequent treatments in the procedure still remain to be examined.

For electron microscope autoradiographs (EM ARG) of hybridized preparations, the most suitable emulsion at present appears to be Ilford L4. Various factors conducive to optimum resolution consistent with maximum efficiency in this emulsion have been pointed out. Practical problems that may arise in autoradio graphs of hybridized preparations such as background and variation of grain density in adjacent sections have also been considered.
Cell proliferation in the prostate complex of the castrate mouse
Authors: Alison M. R. , Wright N. A. , Morley A. R. , Appleton D. R.
Published: August 2011

Cell proliferation during 100 h of continuous androgen challenge was studied in the seminal vesicle and coagulating gland of Balb/c mice castrated 3 days or 14 days prior to the first daily injection of 250 μg testosterone propionate. Continuous labelling with [3H] thymidine indicated that the seminal vesicle was almost totally responsive to androgen, as early as 3 days after castration, whereas the androgen sensitivity of the coagulating gland increased from 30% at 3 days after castration to 85% at 14 days after castration. In both tissues the magnitude of the proliferative reaction could be related to the extent of cell loss prior to stimulation. The duration of the pre‐replicative phase in the response of the seminal vesicle to androgen was 20–25 h both at 3 and 14 days after castration. In the coagulating gland the pre‐replicative phase was 40 h at 3 days after castration and 20 h at 14 days after castration.

The maximum uptake of [7α‐3H] testosterone administered to mice 3 days after castration was significantly greater (P < 001) in the seminal vesicle compared to the coagulating gland. At 14 days the seminal vesicle and coagulating gland exhibited a similar capacity for uptake.

The in vivo metabolism of [7α‐3H] testosterone was studied by thin layer chromatography 30 min and 120 min after administration. A high proportion of the radioactivity extracted from all the tissues was associated with highly polar steroids. At 3 days after castration, the seminal vesicle, 2 h after administration of radioactive testosterone, retained a much higher proportion of radioactivity associated with dihydrotestosterone than did the coagulating gland.

The localization of steroid in mice 3 days after castration was studied by drymount autoradiography at intervals up to 2 h after the injection of [1,2,6,7(n)‐3H]‐testosterone. A heavier deposition of silver grains was observed over autoradiographs of the seminal vesicle. In the seminal vesicle the grains were primarily located over nuclear areas whereas in the coagulating gland the grains were diffusely distributed over both nuclear areas and over cytoplasmic areas.
Production of multi‐level radioactive source for autoradiographic calibration
Authors: Stevens G. W. W.
Published: August 2011

Many reactions are known for converting developed silver images into chemical forms containing a wide variety of elements. By application of this principle to step‐wedge images and by use of labelled reagents, multi‐level flat sources for autoradiographic calibration can be made simply. Detailed procedures have already been published for the use of 131I, 110Ag, and 60Co, and the method can probably be extended to other radionuclides.
Anhydrous fixation of dry plant tissue using non‐aqueous fixatives
Authors: Hallam N. D.
Published: August 2011

Non‐aqueous preparation techniques such as freeze fracture of the dry tissue, fixation using dimethylsulphoxide as a vehicle for glutaraldehyde, and osmium vapour as a fixative have been used to investigate the fine structure of plant material in the dry state. Fixation using anhydrous glutaraldehyde dissolved in dimethylsulphoxide preserves existing cell structure and cell wall characteristics whereas conventional aqueous fixation methods hydrate the tissue during fixation and this gives a distorted impression of true cell structure.
A simple electrode for metallic replication
Authors: Bank Harvey , Robertson J. David
Published: August 2011

A simple resistive heating electrode has been designed for use in metallic replication procedures. These electrodes are relatively small, reliable, adaptable to most vacuum systems, and are compatible with ultra‐high vacuums. They are easily aligned, have good electrical conductivity and adjustable tensions. Using these electrodes with full wave rectified a.c, we found reduced specimen heating, lower background granularity, and improved resolution compared to commercially available designs.
Quantifying ‘pattern’: A stereological approach
Authors: Orive Luis‐M. Cruz
Published: August 2011

At present, a number of stereological techniques are available for the estimation of size parameters of aggregates (such as VV, SV, size distributions, and so forth) from data measured on plane sections.

In this paper, an attempt is made to find a suitable quantification of spatial relationships which can be satisfactorily used for discrimination purposes whenever the traditional size parameters fail to do so.

The proposed techniques of pattern analysis are very simple and strongly connected with the classical theory and practice of stereology; this should render them very accessible to scientists working in different fields, such as biology, geology, ecology, geography, etc.
Cell surgery by laser micro‐dissection: A preparative method
Authors: Isenberg G. , Bielser W. , Meier‐Ruge W. , Remy E.
Published: August 2011

A new UV‐laser device is introduced as a micro‐manipulator and micro‐dissection apparatus for experimental cell research. High energy irradiation is produced by a quasi‐continuous N2‐laser. The laser micro‐beam can be focused to a minimal diameter of 0.75 μm. The micro‐laser can be used for cutting and, hence, as a micro‐surgical instrument at the level of cellular organelles.

Cytoplasmic actomyosin fibrils (AM fibrils) from tissue culture cells (RMCD–cells) are isolated from the surrounding ground cytoplasm. It is shown that the contractile proteins are not damaged by the laser dissection method to an extent that would prevent their normal function, e.g. contraction.
Precise and general conditions for the validity of a comprehensive set of stereological fundamental formulae
Authors: Miles R. E. , Davy Pamela
Published: August 2011

The usual derivations of the well‐known fundamental formulae of stereology are unsatisfactory. Precise and general conditions for the validity of a comprehensive system of such formulae are given. They take the form of unbiased ratio estimators of stereological fractions. These estimators are defined for various types of ‘weighted’ random plane and line sections of the specimen. Thanks to certain probabilistic equivalences, these sections may in practice be implemented fairly easily. The system includes new formulae which allow the estimation of the mean lineal and areal projections of embedded features. The mean square errors of several alternative estimators of the same feature characteristics are compared.
Particle size‐shape distributions: The general spheroid problem
Authors: Orive Luis‐M. Cruz
Published: August 2011

The development of stereological methods for the study of dilute phases of particles, voids or organelles embedded in a matrix, from measurements made on plane or linear intercepts through the aggregate, has deserved a great deal of effort.

With almost no exception, the problem of describing the particulate phase is reduced to that of identifying the statistical distribution—histogram in practice—of a relevant size parameter, with the previous assumption that the particles are modelled by geometrical objects of a constant shape (e.g. spheres). Therefore, particles exhibiting a random variation about a given type of shape as well as a random variation in size, escape previous analyses. Such is the case of unequiaxed particles modelled by triaxial ellipsoids of variable size and eccentricity parameters. It has been conjectured (Moran, 1972) that this problem is indetermined in its generality (i.e. the elliptical sections do not furnish a sufficient information which permits a complete description of the ellipsoids). A proof of this conjecture is given in the Appendix. When the ellipsoids are biaxial (spheroids) and of the same type (prolate or oblate), the problem is identifiable. Previous attempts to solve it assume statistical independence between size and shape. A complete, theoretical solution of the spheroids problem—with the independence condition relaxed—is presented.

A number of exact relationships—some of them of a striking simplicity—linking particle properties (e.g. mean‐mean caliper length, mean axial ratio, correlation coefficient between principal diameters, etc.) on the one hand, with the major and minor dimensions of the ellipses of section on the other, emerge, and natural, consistent estimators of the mentioned properties are made easily accessible for practical computation.

Finally, the scope and limitations of the mathematical model are discussed.
Plastic deformation during freeze‐cleavage: a review
Authors: Sleytr U. B. , Robards A. W.
Published: August 2011

Examples of plastic deformation are illustrated from a wide range of specimens that have been prepared for electron microscopic examination by fracturing at low temperature prior to replication of the frozen surface. Deformation has been shown to occur in some specimens when fractured at temperatures as low as 4 K.

Plastic deformation is recognized in non‐biological polymers such as polystyrene and polyacrylate latex spheres, as well as in similar biological molecules such as poly‐β‐hydroxybutyrate (PHB). However, it is also demonstrated that plastic deformation occurs widely in more complex biological systems, including membranes and protein macromolecules.

The interpretation of the structure of fracture faces of frozen membranes, and particularly the lack of complementarity on opposing fracture faces, is discussed in relation to deformation artifacts.

It is concluded that very considerable energy must be dissipated as heat during the cleavage process. In the case of some of the latex spheres, the glass transition temperature (Tg) of the bulk polymer can be more than 200 K above the cleavage temperature, and yet plastic deformation still occurs.

Once a molecule has deformed, its appearance in the final replica may be significantly changed by heating during evaporation of the replica. An empirical attempt has been made to define the factors leading to the ‘survival’ of a deformed particle.

Although the evidence in this review has been drawn from freeze‐fracture and freeze‐etching studies, it is emphasized that the process of cleaving at low temperature—whether in freeze‐fracture techniques or in cryoultramicrotomy—is essentially the same. Therefore the interpretation of structure in ultra‐thin frozen sections will also need to allow for the possibility of deformation artefacts.
On the choice of quadrats in stereology
Authors: Miles R. E. , Davy Pamela
Published: August 2011

It is described how inference concerning the geometrical structure of a two‐phase specimen may be carried out on the basis of sampling subregions or ‘quadrats’. Two basically different situations are considered—firstly when the specimen itself is the centre of interest, and secondly when the specimen is only part of a larger body of interest Weighted random quadrats are shown to be useful in the first case. Serial and multistage sectioning, and the incorporation of supplementary information via Monte Carlo techniques, are also discussed.
A technique for obtaining clean cut surfaces on wood samples prepared for the scanning electron microscope
Authors: Exley R. R. , Meylan B. A. , Butterfield B. G.
Published: August 2011

A technique is described for obtaining clean cut surfaces on wood samples prepared for the scanning‐electron microscope.
Relative frequencies of random intercepts through convex bodies
Authors: Warren R. , Naumovich N.
Published: August 2011

A computer simulation of the random linear intersecting process has been used to derive the relative frequency distributions of random intercepts through selected convex shapes. The classes of shapes chosen for investigation were ellipsoids, rounded cubes, orthogonally‐faceted spheres, rectangular prisms and triangular prisms. Certain shape‐related characteristics of the distributions are pointed out.
Ponceau 2R staining on semi‐thin sections of tissues fixed in glutaraldehyde‐osmium tetroxide and embedded in epoxy resins
Authors: Gori Paolo
Published: August 2011

Proteins were stained (brilliant red) by using 0·5% Ponceau 2R (C.I. 16150) in sulphuric acid (pH 2) at 40°C on sections 1–2 μm thick of tissues fixed in glutaraldehyde‐osmium tetroxide and embedded in epoxy resins. The staining is free from precipitates and does not require the removal of the embedding media.

Section bleaching with 1–2% periodic acid at 40°C for 30–90 min was also carried out in order to obtain a more brilliant colour of the proteins which may be photographed using black and white films.
Polymeric cryoproteetants in the preservation of biological ultrastructure
Authors: Echlin Patrick , Skaer Helen le B. , Gardiner B. O. C. , Franks Felix , Asquith M. H.
Published: August 2011

A study has been made of the physiological effects of three non‐penetrating polymeric cryoprotective agents on sixteen different plant and animal cells and tissues. The cryoproteetants, when used at concentrations at which they are effective in preventing ice‐crystal formation, generally have a lower toxicity to cells and tissue than similar concentrations of glycerol. The relatively low toxicity of these substances suggests that they would be more suitable as cryoproteetants for morphological and analytical studies than the commonly used low molecular weight compounds.
Notes on the estimation of the numerical density of arbitrary profiles: the edge effect
Authors: Gundersen Hans Jørgen G.
Published: August 2011

A description is given of a family of test‐frames for obtaining an unbiased estimate of the numerical density of arbitrary profiles on a section. The counting rule pertaining to the test‐frame is simple and requires no corrections based on other estimated quantities.
Removal of serum from virus suspensions in preparation for immune electron microscopy
Authors: Beesley J. E.
Published: August 2011

Serum from viral suspensions is precipitated by shaking with Freon 112, and after concentration the virus is observed by immune electron microscopy.
A resistance monitor with power cut‐off for automatic regulation of shadow and support film thickness in freeze‐etching and related techniques
Authors: Steere Russell L. , Erbe Eric F. , Moseley J. Michael
Published: August 2011

A resistance monitor with sensors and automatic power cut‐off has been developed to control the thickness of Pt‐C shadow and C replica films in freeze‐etching and related techniques. The monitor and sensors, in conjunction with newly modified evaporators, should considerably reduce the amount of C and Pt required and should prove useful in other applications employing vacuum evaporation of thin films of Pt, C, or other conducting materials.
Optical character of thermally metamorphosed coals of northern England
Authors: Jones J. M. , Creaney S.
Published: August 2011

The Carboniferous sediments of northern England have formed the context for an optical study of the effects of differing geothermal history on the included organic material. In the north of the area, the Northumbrian Trough contains 5000 m of cyclothemic Carboniferous sediments with frequent coals and is probably underlain by Old Red Sandstone rocks. To the south, the Alston Block comprises 1500 m of basically similar Carboniferous sediments underlain by highly metamorphosed Silurian slates and a Caledonoid granite. The contrasting nature of the basements has produced variable geothermal gradients and consequently varying coal rank throughout the Carboniferous succession.

Alteration of the coals and dispersed organic matter in the sediments by the intrusion of a quartz dolerite sill, the Whin Sill, during Stephanian times has been closely examined. The optical changes induced by the thermal metamorphism depend on the initial rank of the sediments. It has been possible to deduce rank profiles through the succession at the time of intrusion; these can be closely related to the character of the basement. The area was subsequently subjected to hydrothermal (lead, zinc) mineralization.
A new semi‐automatic device for autoradiographic coating
Authors: Marshall John , Faulkner David
Published: August 2011

A semi‐automatic device is described for the coating of slides with nuclear emulsions for autoradiography. The design embodies a metal heatsink for warming the emulsion, and an elevating gantry which withdraws coated slides at a controlled constant speed.
Quantitative analysis of particle growth in TiC‐Ni alloys*
Authors: Chermant J. L. , Coster M.
Published: August 2011

The methods of quantitative metallography and stereology have been used to determine the distribution of the diameter of equivalent spheres and hence study the change in particle size of titanium carbide undergoing growth/coarsening in a nickel matrix. The distribution obtained, using the Saltykov method, is in agreement with that proposed theoretically by Hanitzsch for the kinetics of growth controlled by an interface reaction. The change in the Smith shape factor shows that growth of titanium carbide is isotropic.

This is thus an example of the possibilities offered by stereology. The crystal size distribution in three dimensions is closest to the theoretical models.
The use of PIPES buffer in the fixation of mammalian and marine tissues for electron microscopy
Authors: Baur P. S. , Stacey T. R.
Published: August 2011

PIPES, an organic based buffer, was used in the preparation of a variety of marine and mammalian tissues for electron microscopic study. The ultrastructural results demonstrate that this buffer renders superior ultrastructural details to those obtained with some of the more common inorganic buffers especially when long fixation times are required. Furthermore, this buffer system does not appear to contribute extraneous anions or cations to the tissues and thus permits accurate elemental determinations to be performed on thin sections of the plastic embedded specimens by means of energy dispersive X‐ray analysis.