ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00418.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYSecondary ion mass spectrometry (SIMS) is a potentially valuable but not fully exploited technique for problems in biological research. It is valuable because of: (1) detection of all elements and isotopes from mass 1, hydrogen; (2) high sensitivity for physiologically important elements, Na, K, Mg, Ca; (3) ion imaging of elements in areas as large as 250 μm in diameter with a lateral resolution of 0·5 μm; (4) promising efforts at quantitation at levels as low as 0·1 mmol/kg; (5) ability to analyse sequential layers to form a three‐dimensional analysis. The problems which complicate its use are primarily variations in ion emission, presence of polyatomic interferences and tissue preparation. Examples are cited of SIMS analysis of biomineralization, botany, toxicology and physiology, mostly by ion imaging techniques. SIMS has not yet been fully exploited for any single biological problem. In particular, studies using isotope discrimination, quantitative analysis and depth profiling will enhance the usefulness of SIMS as a technique for biological res

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00419.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYPoint‐projection microscopy has been used to obtain the first images of closely spaced (but isolated) unstained ferritin molecules on a tungsten substrate. The microscopy, in conjunction with a digital processing algorithm, produces images which display a striking three‐dimensional quality usually associated with scanning electron micrographs. From these images, an apoferritin diameter of 13 nm has been deduced. This is identical to the diameter of apoferritin obtained from a reconstruction of the molecule using X‐ray coordinate data, but almost 70% larger than that deduced from TEM images of ferritin in which only its iron rich core can be

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00420.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYA stepper motor was attached by way of a speed reducer to the coarse focusing spindle of a light microscope. After exposure of a film frame the stepper motor displaces the microscope stage according to the programmed instructions laid down in the electronic control unit. In this manner the focal plane is changed and serial optical sections of the developing fish blastoderm were recorded on 16 mm film. This design facilitates the analysis of cell behaviour during early development of annual fishes, of either large numbers of cells simultaneously or of individual cells in detail.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00421.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYWe have developed a method utilizing relatively thick ground sections of plastic embedded tissue which affords the resolution obtained with 0·5 μm cut sections. The sections, which are permanently affixed to plastic microscope slides, are much larger in area than ultramicrotome sections. Additional advantages are: sections can be destained and restained and selected areas can be examined with various forms of electron microscopy. Autoradiographic studies are also possible. Although the method has a broader application, it is particularly useful in examining the interface between hard and soft tissue

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00422.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYA microscopic procedure to observe endogenous fluorochromes in superfused tissues is described. In this procedure, a 325 nm beam from a He‐Cd laser is directed through the objective lens of a microscope onto the surface of a brain slice. Fluorescent structures within the tissue can be observed, photographed and measured. A nerve fibre running from the corporis callosi to the dorsal cerebral cortex was studied with this approach. The 325 nm laser beam excited material with an emission peak at 420 nm within a fibre on the cut surface of a rat brain slice superfused with Krebs‐Ringer. A similar fibre was observedin vivoin the exposed mouse brain. Packets of the fluorescent material appear to move within the fibrein vitro.The fluorescence of the fibre was rapidly diminished by cyanide, colchicine, rotenone and the withdrawal of Ca2+. Elevation of [K+] in the superfusate caused a ‘haloing’ of the fibre's granularity without decreasing the total fluorescence. This phenomenon is possibly related to the depolarization by [K+]of neurones. Although the structure of the fluorochrome was not established, it is suggested that it may be a neurotransmitter‐related substance undergoing axonal

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00423.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYA striking network thought to consist of glycosaminoglycan in neonatal cartilage has recently been reported following glycol methacrylate (GMA) dehydration and embedding. This study attempted to learn why the network was not seen in other preparations previously reported.Comparative light and transmission electron microscopy of the network structures was carried out to determine their biological significance. We have shown the networks to be reproducible artefact, attained only following GMA dehydration of glutaraldehyde fixed neonatal cartilage.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00424.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYThe computational procedures and theoretical approximations used in the real space approach to dynamical electron diffraction calculations are discussed. Although the method is theoretically sound it is found to be unsuitable for rapid and accurate computation of electron wavefunctions.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00425.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYA technique of perfusion fixation following elective diastolic cardiac arrest was developed to obtain excellent preservation of foetal lamb hearts for morphological studies with electron microscopy. A technique was developed to markedly enhance the contrast of embedded material by treating thin sections with tannic acid prior to lead staining. This technique has been particularly useful for quantitative morphometric analysis.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00426.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYLeucocytes were isolated from the peripheral blood of normal individuals and prepared for SEM observation. The addition of the buffer Hanks and Hepes to the glutaraldehyde fixative was found to maintain the initial ambient pH throughout cell manipulation, and to allow satisfactory preservation of surface architecture.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00427.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY