摘要:

SUMMARYA scanning proton microprobe is described which operates in ultra‐high vacuum with a resolution of 10 μm. The operating principles and main features of the design are discussed and the ability of such an instrument to detect trace elements down to a few parts per million by mass is illustrat

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01175.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

SUMMARYA system of data recording and analysis has been developed by means of which simultaneously all data from a scanning instrument such as a microprobe can be quantitatively recorded and permanently stored, including spectral outputs from several detectors. Only one scanning operation is required on the specimen. Analysis is then performed on the stored data, which contain quantitative information on distributions of all elements and spectra of all regions.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01176.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

SUMMARYA procedure is described for the preparation and comparison of complementary freeze‐fracture‐freeze‐etch specimens. These complementary replicas reveal the value of etching some specimens even when the cryoprotectant concentration amounts to as much as 25% glycerol and 25% sucrose. As expected, the peplomers on the outer surface of the surrounding membrane of potato yellow dwarf virus are clearly revealed on the etched specimens but nearly invisible in the complementary freeze‐fracture specimen. Unexpected differences in the internal structure of vesicles within a freeze‐etched chloroplast have been revealed. The cross‐fractured surfaces of some other vesicles have a rough structure, whereas the complementary freeze‐etch surfaces, also shadowed at 123 K, are extremely smooth, suggesting that the contents must have been liquid at 175 K. Large ice crystals form within tobacco mosaic virus (TMV) crystals in infected cells frozen rapidly without cryoprotectant. Cryoprotectant consisting of 25% glycerol and 25% sucrose prevents formation of ice crystals when these specimens are frozen under the same conditions. When cryoprotectant concentrations are decreased from the above level, ice crystals within the TMV crystals are often clearly demonstrated in the freeze‐etch specimen but not in the complementary freeze‐fracture specimen. These results suggest that the complementary freeze‐fracture‐freeze‐etch procedure and the extremely fragile TMV crystalline inclusions are ideal for examining the value of various cryoprotectants and the effect of freezing rates, etching temperatures, and etching t

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01177.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

SUMMARYThe imaging characteristics of a confocal scanning light microscope (CSLM) with high aperture, immersion type, lenses (N.A. = 1·3) are investigated. In the confocal arrangement the images of the illumination and detector pinholes are made to coincide in a common point, through which the object is scanned mechanically. Results show that for point objects the theoretically expected improved response by a factor of 1·4 in comparison with standard microscopy can indeed be realized. Low side lobe intensity and absence of glare permits the imaging at high resolution of weak details close to strong features. A further improvement by a factor of 1·25 in point resolution in CSLM is found after apodization with an annular aperture. Due to the scanning approach all possibilities of electronic image processing become available in light microsco

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01178.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

SUMMARYThe optical arrangement for confocal scanning light microscopy can be incorporated in various imaging modes. Light microscopical specimens can be imaged with contrast enhanced, under γ‐control, inverted, etc. In interference, conditions can be set such that either pure phase or pure amplitude images result. Stereoscopic images at arbitrary aspect ratios can be realized in CSLM by electronic processing of the data obtained when the specimen is sampled with more than one confocal point concurrently. Also forms of differential imaging either amplitude or phase are possible. The coupling of these imaging modes with the improved resolving powers of CSLM results in some unique imaging opportunities, especially of value for high resolution light microscopy of living specime

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01179.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

SUMMARYAn electron microscopic study was carried out to examine the quality of ultra‐structural preservation of parenchymatous and mesenchymatous tissues and isolated cells fixed in glutaraldehyde with sodium azide (NaN3) as an additive.The dense tissues fixed with conventional glutaraldehyde containing calcium chloride demonstrated only a narrow zone of good tissue preservation on the surface of the specimens. Addition of azide at a concentration of 0·1% greatly improved the cellular preservation in the deeper region of tissues, in particular with respect to the mitochondrial morphology. There was no adverse effect on other cell organelles. The improvement in mitochondrial preservation and the enhancement of penetration of the fixative is presumably due to selective and instantaneous inhibition of mitochondrial metabolic activity by the azide, thus retarding anoxic degenerative effects on cellular structures until permanent fixation is completed by the comparatively slow‐acting aldehyde. However, the addition of azide offers no significant improvement in the ultrastructural preservation of isolated lymphocytes and liver cells, or fibroblasts maintained in cul

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01180.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

SUMMARYA method is described for the simultaneous demonstration of 6‐3H thymidine incorporation and acid phosphatase activity in cryostat sections of mouse thymus. The method enables a comparison of mitosis and acid hydrolase activity to be made in the same tissue section. In 8‐week‐old mice acid phosphatase positive cells represent 1·23 ±0·06% of the total population and 8·4 ± 0·27% of the cells incorporate tritiated thymidine. Acid phosphatase activity can be used to estimate cell autolysis and death. The implications of the method in relation to tissue dynamics i

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01181.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

SUMMARYThe present study was undertaken to report a new method which reveals the ultrastructure of freeze‐fractured membrane faces. The method consists of initial replication of fractured surfaces of frozen specimens with evaporated carbon and treatment of the replicas with a negative staining solution after dissolution of specimens. This negative staining‐carbon replica method reveals clear distribution, ultrastructures and precise size of intramembrane particles on the fractured membrane faces by means of density difference of negative staining solution which is deposited on the surfaces of carbon repli

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01182.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

SUMMARYAnalysis of pulmonary structure‐function relationships by microscopy requites that the lung be fixed under carefully controlled physiological conditions, since lung structure is extremely responsive to the relationship between airway and vascular pressures. Unfortunately, standard post‐mortem fixation techniques leave some doubt as to the exact relationship between these pressures during fixation. This problem can be circumvented by stabilizing lung structure by rapid freezing under carefully controlled physiologic conditions. Using ethylene glycol in a freeze substitution technique we have developed procedures which yield a degree of preservation compatible with the high degree of resolution of the electron microscope. These can be used to obtain a more detailed understanding of pulmonary structure‐function relationships under well‐defined physiological con

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01183.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

SUMMARYThe accuracy of absolute quantitation within thick, mineralized tissue specimens is influenced by count rate variations of characteristic X‐rays during electron microprobe analysis. The variations occur for electron doses10−10C/μm2and are primarily dependent upon the light element fraction within the irradiated volume. Specimen preparation procedures affect both count rate dynamics and interpretation of microanalytical results. X‐ray intensity data acquired at initial electron exposure and utilized in standard matrix correction schemes will project valid elemental concentrations for known calcium compounds over wide ranges of specimen density. Measurement error could approach ±2–3% for the major elemental constituents in mineralized tissues, but only with appropriate control or interpretation of electron irradiation

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1979.tb01184.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY