共查询到20条相似文献,搜索用时 15 毫秒
1.
Two methods of sample preparation, originally developed for transmission electron microscopy and better at preserving bacterial exopolymers than the traditional fixation with glutaraldehyde, were adapted for scanning electron microscopy. The first involves a glutaraldehyde-lysine mixture as a fixative. The second, based on the use of polycationic ferritin, was modified to include a post-fixation step with either glutaraldehyde or a glutaraldehyde-lysine mixture. These techniques were found to improve considerably the preservation of exopolymers secreted by three bacterial strains. 相似文献
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Improved ultrastructural preservation of yeast cells for scanning electron microscopy 总被引:1,自引:0,他引:1
The processing of yeast cells for scanning electron microscopy by conventional sequential fixation with glutaralde-hyde and osmium tetroxide and subsequent dehydration and critical point-drying caused pronounced deformation and visible shrinkage in all basidiomycetous and ascomy-cetous yeast strains studied. The mean cell diameter decreased to nearly 60 and 70%, respectively. After an additional sequential fixation with 1% tannic acid and 0–5% uranyl acetate the cell shrinkage was significantly reduced, but the most important result was a considerable reduction of wrinkling and deformation of the yeast cells. 相似文献
3.
Due to the solubility of lipids during dehydration of specimens for SEM (Scanning Electron Microscopy), the relation of lipids to special tissue structures remains obscure. The tricomplex flocculation as described by Elbers, Ververgaert and Demel (1965) is found to be an excellent method of fat and tissue preservation. The steps of the procedure are explained in the preparation of a tuberous xanthoma. 相似文献
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The preservation of surface-associated micro-organisms prepared for scanning electron microscopy 总被引:3,自引:0,他引:3
Scanning electron microscopy (SEM) has become a popular means of studying micro-organisms which associate with surfaces. However, as yet no detailed examination has been made of the influence of specimen preparation on the number of organisms finally seen on the SEM screen. In this investigation critical assessment is made of the influence of a wide range or preparative factors on the preservation of filamentous bacteria associated with the epithelial surfaces of rat intestine. Organisms were quantitated using a rigorous counting method (transect line analysis); statistical testing of these counts enabled the comparison of different preparative factors. The composition of the fixative was found to significantly influence the number of organisms preserved; of the fifteen fixatives studied, Karnovsky's fixative with ruthenium red best preserved surface-associated organisms. The influence of other factors on the number and appearance of preserved organisms was also examined. These factors included the washing of specimens prior to fixation, the storage of fixed specimens, and the handling and storage of critical point dried specimens. The results are discussed with reference to the optimal methods for preparing specimens for SEM. 相似文献
7.
The preservation of mitochondria, cytoplasmic vacuoles and cytoplasm by various fixatives after various pretreatments of ethothelial heart cells from Xenopus laevis tadpoles in tissue culture was investigated. The study was based on phase contrast cinemicrographic recordings and on qualitative and quantitative observations with the electron microscope. Three fixatives were used: 3% glutaraldehyde in phosphate buffer, followed by 1% osmium tetroxide postfixation, fixation only with 1% osmium tetroxide in phosphate buffer and the fixing medium according to Dalton. Cells were either not treated or pretreated for 20 min: 10 microM FCCP (Carbonylcyanide-p-trifluoromethoxy-phenylhydrazone) or 4 mM KCN. The superiority of glutaraldehyde was exemplified by its very rapid action, good preservation of cytoplasm, vacuoles, and mitochondria. It was the only medium which maintained an electron density of the mithochondria matrix. In both of the other fixatives swelling of mitochondria and coagulated appearance of cytoplasm (in phase contrast) was more pronounced in cells pretreated with metabolic inhibitors than in controls. Observations with the light microscope have been confirmed by morphometry of electron micrographs of mitochondria. The relation of matrix space to intracristal space is changed in opposite directions after glutaraldehyde and after the Dalton-type fixation. The results indicate a higher sensitivity against fixation artifacts in cells under pathological conditions than normal cells. 相似文献
8.
A technique is described for arresting rapid movement of living cells and preserving their fine surface structures for scanning electron microscopy. Rapid freezing is recommended as the method of immobilization and freeze substitution has been employed to fix and dehydrate the specimens; this technique is more reliable than osmium fixation, both in terms of obtaining a much higher proportion of good results and in the improved preservation of detail. Various techniques of substitution have been investigated for best preservation, and the roles of the constituents of the substitution mixture have been discussed. 相似文献
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H H Mollenhauer 《Journal of microscopy》1978,113(2):215-216
A method that utilizes samples preserved and stored in Lugol solution is described. The samples are postfixed in osmium tetroxide, rapidly dehydrated in absolute ethanol and dried by the critical point drying technique. Aliquots of several samples can be processed simultaneously. Surface details of algae stored in Lugol and processed by this method are comparable to those found in conventional preparative procedures. No loss of nannoplankton or other small sized fractions have been observed. 相似文献
11.
P.J.B. KOECK 《Journal of microscopy》2015,259(1):74-78
Zernike phase contrast has been recognized as a means of recording high‐resolution images with high contrast using a transmission electron microscope. This imaging mode can be used to image typical phase objects such as unstained biological molecules or cryosections of biological tissue. According to the original proposal discussed in Danev and Nagayama (2001) and references therein, the Zernike phase plate applies a phase shift of π/2 to all scattered electron beams outside a given scattering angle and an image is recorded at Gaussian focus or slight underfocus (below Scherzer defocus). Alternatively, a phase shift of ‐π/2 is applied to the central beam using the Boersch phase plate. The resulting image will have an almost perfect contrast transfer function (close to 1) from a given lowest spatial frequency up to a maximum resolution determined by the wave length, the amount of defocus and the spherical aberration of the microscope. In this paper, I present theory and simulations showing that this maximum spatial frequency can be increased considerably without loss of contrast by using a Zernike or Boersch phase plate that leads to a phase shift between scattered and unscattered electrons of only π /4, and recording images at Scherzer defocus. The maximum resolution can be improved even more by imaging at extended Scherzer defocus, though at the cost of contrast loss at lower spatial frequencies. 相似文献
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A post-polymerization en bloc staining method for high voltage electron microscopy is described. Embedded specimens were initially trimmed to an area close to the point of interest. Trimmed blocks were stained in 5% uranyl acetate/75% ethanol solutions for 36 h at 333 K. This procedure allowed specimens to be stained without the necessity of exposing Formvar films to damaging solutions. After such staining, both the contrast and fine detail of structures such as microfilament bundles were superior to that seen in material stained with aqueous solutions of uranyl salts. 相似文献
13.
Two specimen holders for use in scanning electron microscopy (SEM) of insect and other specimens glued to triangular cardboard points are described. They have important advantages over standard metal stub mounts. Diverse, precisely orientated, viewing angles are possible using single specimens, which can afterwards be re-pinned for return to the collection. 相似文献
14.
Growing and embedding monolayer cells in situ in beem capsule caps for light and electron microscopy
Edward Asafo-Adjei Eugene F. Bernard Tatsuo Hase 《Microscopy research and technique》1987,5(4):367-372
A method of growing and embedding monolayer cells in situ on the inner surface of the Beem capsule for light and electron microscopy is described. The results demonstrate that wandering cells in tissue and collected cells in suspension are readily grown on the Beem capsule and embedded in situ by a slight modification of the routine embedding procedure. The method seems to be particularly suited for studies of interactions between growing monolayer cells and various substances, infectious agents, or other types of cells added during the incubation period, where disruption by scraping and pelleting, or enzymatic reaction to remove the cells, would prevent such data from being gathered. The method is also suited for light and electron microscopic studies of minute tissue or organs, such as dissected mosquito salivary glands, whose embedding by the routine procedure is difficult. 相似文献
15.
Rose H 《Ultramicroscopy》2005,103(1):1-6
Future aberration-corrected electron microscopes that will enable sub-Angstroem spatial and sub-eV energy resolution are outlined . The sub-Angstroem transmission electron microscope (SATEM) only compensates for the spherical aberration and reduces the chromatic aberration disc by means of a monochromator. In order to correct for both aberrations, two novel correctors, the ultracorrector and the superaplanator are proposed which will yield a resolution limit of about 0.5A and a large field of view of more than 4 x 10(6) image points. The superaplanator is best suited for obtaining an achromatic aplanat required for the realization of the high-performance in situ electron microscope of the TEAM project. 相似文献
16.
Two different freeze-fracture methods are explored for preparation of biological material for scanning electron microscopy. In the simpler method the tissues are first fixed and dehydrated. They are then frozen and fractured, and after thawing, critical-point dried. This method has already been used in a number of studies of animal tissues (heart, liver, kidney). It is applied here to the examination of plant material (leaf mesophyll cells). In the second method tissues, or cells, are first infiltrated with cryoprotectant (dimethylsulphoxide) then frozen and fractured, and not fixed until after thawing. The fixed tissues are finally dehydrated and critical-point dried. This method also has previously been used in the study of animal tissues, and is applied here to carrot protoplasts, chicken erythrocytes, and leaf mesophyll cells. 相似文献
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In the past decade, investigators of cryo-planing for low-temperature scanning electron microscopy (cryo-SEM) have developed techniques that enable observations of flat sample surfaces. This study reviews these sample preparation techniques, compares and contrasts their results, and introduces modifications that improve results from cryo-planing. A prerequisite for all successful cryo-planing required a stable attachment of the specimen to a holder. In most cases, clamping with a screw mechanism and using indium as space-filler sufficed. Once this problem was solved, any of three existing cryo-planing methods could be used to provide successful results: cryo-milling, microtomy in a cold room, and cryo-ultramicrotomy. This study introduces modifications to the cryo-planing technique that produces flat surfaces of any desired plane through a specimen. These flat surfaces of frozen, fully hydrated samples can be used to improve observations from cryo-SEM as well as to enhance results from x-ray microanalysis and (digital) image analysis. Cryo-planing results of chrysanthemum (Dendranthema x grandiflorum Tzvelev) stems, hazel (Corylus avelane L.) stems, and repeseed (Brassica napus L.) pistils are presented to illustrate the use of the planing method on fibrous, hard, and delicate materials, respectively. 相似文献
18.
M Stewart 《Journal of microscopy》1973,97(3):381-383
Evidence is presented to suggest that staining biological material prior to examination by electron microscopy with poly-iodinated aromatic molecules may give contrast enhancement comparable to that obtained with uranyl acetate. This technique could enable the production of highly specific electron-opaque stains analogous to the organic dyes employed in light microscopy. 相似文献
19.
Z. Kristóf 《Journal of microscopy》1997,188(1):88-91
A rapid method is described for obtaining ultrathin sections from light microscopy sections. Five-micrometre epoxy sections, heat-flattened to slides, were affixed to the tips of plastic blocks by light-curable dental bond, and cured while still on the microscope stage by illumination with blue light for 2 min. Sections were detached from the slides by rapid cooling and then resectioned for electron microscopy. 相似文献