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Preface
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- By D.C. Sigee, Manchester, A.J. Morgan, Cardiff, A.T. Sumner, Edinburgh, Alice Warley, London
- Edited by David C. Sigee, University of Manchester, John Morgan, University of Wales, Aberystwyth, Adrian T. Sumner, Alice Warley
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- Book:
- X-ray Microanalysis in Biology
- Published online:
- 04 August 2010
- Print publication:
- 22 April 1993, pp xiii-xiv
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- Chapter
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Summary
The technique of electron probe X-ray microanalysis (XRMA), by which the elemental composition of specimens can be determined on a microscopical scale, has now been applied to biological materials for about 30 years, and in that time has made many valuable contributions to a variety of biological problems. To improve awareness of the technique, and to provide a discussion forum for those interested in biological XRMA, the Biological X-ray Microanalysis Group was formed in Britain some five years ago. Although its primary purpose was to hold regular meetings, the possibility of producing a book which reviewed both developments in the equipment and the wide variety of applications for which XRMA could be used was another aim, now realised in the present volume. This book arose out of a meeting held by the Biological X-ray Microanalysis Group in Manchester, England, in April 1991. What we have tried to produce is not simply another set of conference proceedings, but a well balanced and integrated series of chapters describing the hardware and software used for XRMA, the necessary procedures for specimen preparation and quantification, and the enormous range of applications of the technique in biology.
It might be supposed that after 30 years' application of biological X-ray microanalysis, the field might be settling down to a comfortable but perhaps rather routine maturity. The contributions in this book show, however, that this is far from being so, with many exciting developments in all aspects of the subject.
9 - X-ray microanalysis in histochemistry
- from SECTION C - SPECIMEN PREPARATION
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- By A.T. Sumner
- Edited by David C. Sigee, University of Manchester, John Morgan, University of Wales, Aberystwyth, Adrian T. Sumner, Alice Warley
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- Book:
- X-ray Microanalysis in Biology
- Published online:
- 04 August 2010
- Print publication:
- 22 April 1993, pp 133-150
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Summary
The suitability of X-ray microanalysis for histochemistry
The great majority of applications of X-ray microanalysis (XRMA) in biology may be regarded as histochemical, in the sense that they are studies of the chemical composition of cells or tissues in situ. Conventionally, however, the term histochemistry is used to denote the investigation of the chemistry of cells and tissues in situ using specific reactions that produce a distinctive reaction product that can be detected by some microscopical method. For light microscopy, a coloured reaction product is normally used. Although this approach has been extremely successful, not every cellular substance of interest can be identified in this way. In addition, coloured reaction products may diffuse, or dissolve in mountants, and can rarely be quantified satisfactorily. For electron microscopy, reliance is placed on reaction products which are electron dense. As well as the problems of diffusion and quantification noted above for light microscopical histochemistry, it may also be difficult at times to distinguish the reaction product from the normal staining of the section. Alternatively, if the section is left unstained, the histochemical reaction product may be clearly visible, but difficult to localise because of the low contrast of the rest of the material. X-ray microanalysis has the potential to help with all these problems.
Problems of diffusion of histochemical reaction products are likely to be greatest in multi-step reactions, such as those for many enzymes.