摘要:

AbstractCryotechnical processing of cartilage has the potential to solve many of the tissuespecific problems associated with various routine chemical fixation protocols. This is particularly the case with respect to extracellular matrix architecture, the distortion or destruction of which (caused by extraction and/or precipitation of proteoglycan molecules) may be prevented. Adoption of such techniques also permits high‐sensitivity immunoelectron‐microscopy of the extracellular matrix space (carbohydrate epitopes). However, a number of difficulties still remain to be resolved, particularly that of matrix‐cell interface separation occurring during freeze substitution and low temperature embedding. These problems are briefly addressed and possible solutions outlined. © 1993 Wiley‐L

ISSN:1059-910X    

DOI:10.1002/jemt.1070240602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this study, we have applied the techniques of high pressure freezing and freeze substitution to embryonic cell types which are usually difficult to fix properly for electron microscopy. In bothDrosophilaandStrongylocentrotus purpuratus, we see improved preservation of both membrane systems and cytoskeleton when compared to published results on the same cells using conventional electron microscope (EM) fixation methods. Finally, we have seen that postembedding labelling of sections is possible even after light osmium fixation during freeze substitution. © 1993 Wiley‐Liss, I

ISSN:1059-910X    

DOI:10.1002/jemt.1070240603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractAs compared to classical chemical fixation, the physical immobilization of ultrastructures by fast‐freeze fixation (FFF) and the subsequent exchange of water in its solid state by freeze substitution (FS) improve the preparation procedure for immunogold labeling (IGL).FFF‐FS results in a morphological preservation of unchallenged quality, as well as in a better preservation of antigenic reactivity, thus allowing remarkable precision of labeling on sections.However, FFF, particularly over a cooled metal plate, requires a heavy and expensive machine. It is not suitable for all biological specimens and in the best conditions, which remain difficult to standardize, the thickness of the well‐preserved portion of the specimen does not exceed a few μm for compact tissues, and exceptionally 30–40 μm for isolated cells.The FS procedure is long and must be adjusted empirically for every new specimen and antigenic detection. The preservation of a given antigen's reactivity in the presence of fixative agents and embedding resins remains unpredictable. The action of fixative agents is different and milder in FS than when they are used classically in chemical fixation. By chance, one of the best FS procedures for the preservation of both ultrastructure and antigenicity appears to be by using acetone alone, together with a molecular sieve to improve the water exchange process. A large choice of embedding resins usually allows us to find a compromise between ultrastructural and antigenic preservation. © 1993 Wiley

ISSN:1059-910X    

DOI:10.1002/jemt.1070240604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractMethods of plunge freezing and freeze‐substitution (FS) for insect antennae and similar body appendages are described. In these more or less cylindrical specimens, usually a layer below the cuticular surface of 10–15 μm thickness is well preserved without freezing damage, further inwards ice‐crystal ghosts of increasing size are encountered, but in the very centre of antennal branches (diameter ∼80 μm) of the silkmoth,Bombyx mori, freezing damage is usually reduced again. The frost‐hardy species,Poecilocampa populiandBoreus hiemalis, exhibit regions free from freezing damage up to 40 μm below the cuticular surface. Secondary freezing damage in silkmoth sensory hairs is observed only after deliberately warming the specimens to –43°C for>>10 min before FS. Secondary artefacts due to the substitution process are investigated by comparison with freeze‐etching and by comparing different FS media and protocols. Methanol is not recommended as a substitution medium for insect specimens. Structures particularly liable to substitution damage are the stimulus‐conducting pore tubules of olfactory sensilla and the receptor cell membrane. Extraction of soluble components is more likely with pure organic solvents without added chemical fixing agents and with prolonged substitution at elevated temperatures. Such extraction may also be a possible artefact with soluble antigens in immunocytochemical studies. A review is given of the major achievements attained with these techniques in insect functional morphology and immunocytochemistry. ©

ISSN:1059-910X    

DOI:10.1002/jemt.1070240605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe preparation of cross‐sectional specimens for AEM studies of materials such as ceramic coated tungsten carbide presents some unique problems. Pieces joined by the use of epoxies often separate at the interface between the WC and ceramic coating during the initial mechanical grinding and subsequent thinning process as a result of the vibration and physical strain placed on the sample. These problems have been overcome through the use of a preparation process which essentially encapsulates the sample within the confines of an epoxy filled quartz tube. This preparation process has allowed for facile AEM cross‐sectional analysis of TiN/TiCN coatings on WC‐Co substrates, and has revealed two distinct grain morphologies within the TiCN coating. © 1993 Wiley‐L

ISSN:1059-910X    

DOI:10.1002/jemt.1070240606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractWe have found significant differences between the results of computer simulations of HOLZ line patterns. The computations in question are made in the kinematical approximation. After trivial errors are eliminated the programs fall into two groups. There is a discrepancy between the two that increases with distance from the zone axis. The difference is small but not negligible at the level of precision used in determining lattice parameters or strain.We show which of the two is correct in the kinematic approximation and that the discrepancy between the two groups is of the order of the error introduced by dynamical interaction. © 1993 Wiley‐Liss, I

ISSN:1059-910X    

DOI:10.1002/jemt.1070240607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA new rapid fixation and embedding technique using microwave energy was evaluated for immunolabelling and examination of ultrastructure of plant and insect cells. Tissues in gluteraldehyde‐paraformaldehyde were fixed for fifteen seconds in a microwave at 100% power, and dehydrated. Microwave energy was then used to polymerize the London Resin White (LR White) acrylic resin during the embedding process. Embedded specimens were then thin sectioned (90 nm) and treated with anti‐tomato spotted wilt tospovirus (TSWV) antiserum followed by protein A‐gold label, or antisera against a TSWV encoded nonstructural protein followed by goat anti‐rabbit gold label. Using this technique, structural and nonstructural proteins of TSWV were readily detected and specifically labelled in cells of the insect vector, the western flower thrips,Frankliniella occidentalis(Pergande), and in infected cells of the plant species,Emilia sonchifoliaL. © 1993 Wiley

ISSN:1059-910X    

DOI:10.1002/jemt.1070240608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe membrane specializations of the fresh unfixed kidney cortex of adult and neonatal ICR mice were examined by using rapid freezing replica methods. In proximal tubular cells, numerous apical intracellular tubules exhibited helical patterns on the E face with a pitch of about 12 nm. This regular pattern was often continuous with similar striped indentations on the edge of the vacuoles connecting with the tubules. On the luminal surface (ES) of these vacuoles, membrane surface particles were arranged regularly in striped patterns with a center‐to‐center spacing of about 12 nm. We could not identify differentiations on the PF or PS of the same membrane systems. Another membrane specialization was a plaque or patch of clear pits in tilted lattice alignments on the P face of the large vacuoles with a center‐to‐center spacing of about 20 nm. This type of specialization was often observed in the neonatal mice proximal tubular cells. These membrane specializations may indicate the active membrane functions in the proximal tubules and suggest the functional continuity and structural relationship of these apical endocytic membrane systems. © 1993 Wiley

ISSN:1059-910X    

DOI:10.1002/jemt.1070240609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper describes the coupling between a scanning electron microscope (SEM) and an image analysis workstation. The system was designed in order to drive the SEM and to analyse any sample. It allows automatic (edge detection) or semiautomatic (pointing, marking, drawing) object detection. Two types of data can be obtained: (1) topographical information, such as the location of the object within a region of interest drawn at any magnification of the microscope, or (2) quantitative data, such as morphometric characteristics of objects. In addition, high resolution maps of the section, regions of interest, and objects can be obtained with a laser printer. This software was first applied to quantitate the adhesion of the bacteriaPseudomonas aeruginosato human respiratory epithelial cells in culture.P. aeruginosawas shown associated with ciliated cells. The second application concerned the study of the distribution of specific carbohydrate residues at the surface of the respiratory cells. The gal residues were revealed using the lectinRicinas communisagglutinin II, adsorbed to colloidal gold particles. A relationship between the presence of adherent bacteria and labelling was shown. © 1993 Wiley‐Liss, I

ISSN:1059-910X    

DOI:10.1002/jemt.1070240610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070240611

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY