摘要:

AbstractConventional treatment of tissues for sectioning and transmission electron microscopy uses aldehyde fixation and osmium tetroxide postfixation. Although the result is aesthetically pleasing, osmication destroys some cell components and reduces the chemical activity of others, such as reactions with antibodies and lectins. We have found that aldehyde fixation followed by uranyl acetate preserves and contrasts most structures and visualizes some that are not easily seen after osmication. Aldehyde/UA treated tissues have enough contrast to be observed without section staining while retaining some of the chemical activity that is lost through osmication. Sections of tissues with good preservation and contrast can be used for immunogold and lectin‐gold labelling of at least some molecules. © 1994 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070290102

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

年代:1994

数据来源: WILEY

摘要:

AbstractConventional fixation of the delicate, highly folded rat ciliary body and its iridial extension, as well as of vitreal structures, is associated with the induction of a number of artifacts, thus limiting the reliability of morphological interpretations. Improved ultrastructural preservation may be achieved by microwave heating in combination with osmium tetroxide fixation. This protocol, although simple and cheap, yields results, particularly with respect to the extracellular matrix compartment between inner and outer ciliary epithelial cells, which are not greatly inferior to those obtained by implementing the sophisticated high pressure freezing and freeze substitution technique. The latter affords good to very good ultrastructural preservation of epithelium and stromal components, such as blood vessels, neural elements, smooth muscle cells, fibrocytes, and free cells, up to a depth of 50–100 μm from the tissue surface. Its superiority over osmium tetroxide/microwave fixation is revealed in the cytoplasmic, intraorganellar, and vitreal matrix compartments, which incur no obvious losses. © 1994 Wiley‐Liss

ISSN:1059-910X    

DOI:10.1002/jemt.1070290103

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

年代:1994

数据来源: WILEY

摘要:

AbstractUltra‐thin frozen sections are ideal substrates for immunolabeling in high resolution electron microscopy. However, visualization of subcellular structures is inferior to that obtained with corresponding plastic sections. Although negative staining is generally effective and even superior to positive staining, the accumulated stain is often too heavy, obscuring morphology and markers used for immunocytochemical localization of antigens. This paper describes the development of a modified negative contrast staining technique in which a high concentration of uranyl acetate is mixed with methyl cellulose at a low pH. Application of this stain to cryosections of cells and tissue resulted in improved visualization of morphological structures characterized by negative images of membranes and cell organelles. Use of this stain is advantageous for morphological and immunocytochemical studies involving ultra‐thin frozen sections. © 1994 Wiley‐Lis

ISSN:1059-910X    

DOI:10.1002/jemt.1070290104

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe different functional conditions of pre‐ameloblasts, secretory ameloblasts, and maturation ameloblasts in 9 day rat incisors were recognized using high resolution light microscopic alkaline phosphatase histochemistry: Digital backscattered electron imaging was performed using the block surfaces from which thin sections were taken for histochemical study. It was possible to correlate exact locations in histochemical sections with positions in the block face at all stages of enamel mineralization from early secretion through late maturation. The first steep increase in the rate of mineralization of completed enamel matrix occurs after the first transition from smooth ended ameloblasts to ruffle ended ameloblasts. In the 9 day rat incisors used for this purpose, there are only two smooth to ruffle cyclical transitions, and the width of successional smooth ended bands of ameloblasts in the maturation cycling process is always narrow. Nevertheless, there seems to be a good correlation between mineralization increase and the acquisition of the high alkaline phosphatase activity in the deeply enfolded distal cytoplasm of the ruffle‐ended maturation stage ameloblasts. © 1994 Wiley‐Lis

ISSN:1059-910X    

DOI:10.1002/jemt.1070290105

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

年代:1994

数据来源: WILEY

摘要:

AbstractTritrichomonas foetuswas studied using different physical and chemical fixation methods such as fast‐freezing (by high pressure, “slam‐freezing,” and jet‐propane), freeze‐substitution, conventional freeze‐fracture and deep‐etching, cryoultramicrotomy, and routine preparation for transmission electron microscopy. The use of fast‐freezing fixation (FFF) proved to be superior in terms of structural preservation due to the rapidity of this fixation compared to that obtained using conventional chemical fixation. The low temperature techniques used here were useful to confirm data already obtained by conventional freeze‐fracture using chemical fixation and cryoprotection, such as the presence of flagellar rosettes and costa structure. Cryoultramicrotomy and slam‐freezing also demonstrated the presence of hair‐like structures projecting out from the protozoan surface. New aspects of organelles ofT. foetuswere demonstrated. Published

ISSN:1059-910X    

DOI:10.1002/jemt.1070290106

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

年代:1994

数据来源: WILEY

摘要:

AbstractA simple method for the fabrication of a Au/p‐Si Schottky barrier suitable for electron beam induced current (EBIC) study has been developed. The mechanical and electrical properties of the fabricated Au/p‐Si Schottky barriers have been tested, and EBIC measurements of the dislocation contrast have been conducted using the fabricated Schottky barriers. © 1994 Wiley‐Lis

ISSN:1059-910X    

DOI:10.1002/jemt.1070290107

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe aim of the work is to visualise nuclear pore complexes (NPCs) in mammalian cells by high resolution scanning electron microscopy. A detergent‐free isolation protocol was employed to obtain clean nuclei from the haemopoietic cell line K 562. Nuclear isolation was performed by mechanical homogenisation under hypotonic conditions followed by purification of the nuclear fraction. The isolated nuclei were attached to silicon chips, fixed, critical point dried, and sputter coated with a thin film (3–4 nm) of tantalum. Analysis of the nuclear surface by scanning electron microscopy (SEM) revealed a strong sensitivity of the outer nuclear membrane (ONM) to disruption during the isolation procedure. A significant reduction of the characteristic pattern of damage to the ONM was achieved by means of an isopicnic centrifugation on an isoosmolar balanced Percoll gradient. Analysis of the population of isolated nuclei by flow cytometry showed no signs of cell cycle specific losses of nuclei during isolation. The SEM investigations of the morphology of the nuclear envelope (NE) and of substructural details of NPCs and polyribosomes were performed using an in‐lens field emission scanning electron microscope. © 1994 Wiley‐L

ISSN:1059-910X    

DOI:10.1002/jemt.1070290108

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

年代:1994

数据来源: WILEY

摘要:

AbstractA new method is described which enables the visualization of hidden cellular surfaces of biological tissues. The method does not depend on the kind of fixative solution, the duration of the fixation, or the quantity of extracellular matrix. The samples are chemically dissociated with potassium ethoxide until the first individual cells appear in the solution. This initial process is followed by phase contrast microscopy, and remaining tissue is investigated with scanning electron microscopy. The method has proved more effective than conventional enzymatic techniques and is a simple, quick, and effective way to investigate the three‐dimensional organization of different normal and pathological tissues. © 1994 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070290109

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

年代:1994

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070290110

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

年代:1994

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070290101

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

年代:1994

数据来源: WILEY