ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00430.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00431.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00432.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYIt has long been known that tumour‐bearing tissues often have a significantly higher water content than the normal tissues from which they have been derived. Most of the evidence suggesting this in recent years has been obtained from methods employing nuclear magnetic resonance (NMR), which, although undoubtedly indicative of hydration, cannot at present be precisely quantified. Furthermore it has not been possible by these means to determine whether this overall increase in the water content of the tissue is principally an increase in the extracellular fluid or whether the water content of the tumour cells and the cells immediately adjacent to the tumours increases also. In this investigation, which is the first of its kind, a combination of NMR and immersion refractometry techniques have been used to examine the water content of normal and tumour bearing tissues. NMR measurements were made on pieces of normal and tumour bearing tissue from rat livers: intact living cells were also isolated from these pieces and their refractive indices measured by immersion refractometry from which the water content of their cytoplasm was calculated. It was found that all the cells so measured obtained from hepatomas had more water in their cytoplasm (usually over 5% more water) than any of the cells from normal livers; and that normal‐looking cells taken from the vicinity of hepatomas also all had more water in them than those of normal liver cells, although the differences in this case were less. These results were closely parallel to those obtained by NMR measurements. It is therefore concluded that an appreciable proportion of the increase in the water content of the tissue as a whole that occurs during carcinogenesis, must, in this tissue, be an increase in intracellular wa

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00433.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYThe development of quantitative interpretation of electron micrographs, in respect of contrast as well as resolution, has followed similar lines to those in optical microscopy, though on a faster time scale. A thorough understanding of phase contrast came relatively late in both disciplines. The definition of resolution is more complicated in the case of the electron image on account of the severe effect of lens aberrations, especially spherical aberration. Experimental measurement of the performance of an electron microscope requires an operational definition of resolving power, which must include contrast considerations as well as the limitations imposed by lack of spatial and temporal coherence of the electron source. Agreement on suitable test procedures is now being reached, at least for a very thin specimen.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00434.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYA simple vector analysis of the diffraction of light by an ideal, extended phase grating suggests that irrespective of the amount of retardation imposed on the light passing through a transparent microscopic object the diffracted light leaving the object plane is precisely 90° out of phase with the resultant direct (zero‐order diffracted) light. In positive phase contrast microscopy, with a 90° phase plate of transmittanceTfor the direct light, the image and halo respectively have intensities relative to the original illumination of (√T.cos 1/2Φ–sin 1/2Φ)2and (√T.cos 1/2Φ+sin 1/2Φ)2. The empty background has an apparent intensity ofT.Zero intensity of the image is seen ifT=tan2(1/2Φ), and reversal of contrast ifT≤tan2(1/4Φ). The same equations can be used to predict the intensities of the image and halo in negative phase contrast microscopy, if Φ is replaced by (360°‐Φ).Unlike the ‘standard’ description of phase contrast microscopy, exemplified by Barer's vector method, the present account is consistent with the conservation of energy and is not restricted to very small object retardations. Barer's method is, however, theoretically valid for objects of any shape, and the two approaches may perhaps be

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00435.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYThe interaction between histochemistry and microscopy for quantifying the morphology and function of cells in sections of tissue is reviewed.In principle, the morphological parameters of cells can be measured in suitably‐stained sections using image analysers. In practice, however, the individual cells often cannot be distinguished from each other in such systems. This problem might be overcome, at least in muscle, by visualizing types III and IV collagen in the connective tissue and basement membranes surrounding the cells.The functional capacities of cells within tissues can be inferred by measuring the activities of their key enzymes with quantitative histochemical techniques. At present, the wrong enzymes are frequently chosen for this purpose. Flux‐generating and physiologically significant enzymes are preferable, but this requires new histochemical techniques to be devised and validated quantitatively for use with the computer‐assisted analytical microscopes that are now becoming available commerc

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00436.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYThe endoplasmic reticulum has the enzymic machinery for the synthesis of both protein and phospholipid and hence plays a central role in its own biogenesis and that of other cellular membranes. The evidence available concerning the biogenesis of the phospholipid bilayer of the endoplasmic reticulum, particularly from the application of fine structural cytochemical methods for the localization of acyltransferases, is reviewed. The observations are consistent with a model in which phospholipid is synthesizedin situat the site of membrane growth. Synthesis is asymmetric, with most enzymes located at the cytoplasmic side of the membrane, and controlled transmembrane movement of phospholipid results in an asymmetric bilayer.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00437.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYThe present study was designed to clarify the morphological nature of epithelial‐connective tissue attachment by quantitative comparison of palatal and buccal mucosae. Tissue samples were obtained from ferrets and, following a strict sampling regime, sections were obtained for quantitative light and electron microscopy. Electron micrographs from the epithelial‐connective tissue junction were subjected to analysis by stereological intersection counting. Quantitative results show that palatal epithelium has a comparatively convoluted interface, and is twice as thick as buccal epithelium. Stereological data are presented for relative surface area of basal plasma membrane occupied by hemidesmosomes, mean hemidesmosomal diameter and numerical density of hemidesmosomes per unit area of basal plasma membrane. Larger hemidesmosomes are found in the palatal epithelium. Results suggest that a prominent rete‐ridge pattern, as seen in the palatal epithelium, along with a greater specialized surface for adhesion, may be responsible for providing epithelial‐connective tissue stability in regions subjected to high mechanical

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00438.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

SUMMARYThe autoradiographic methods used in biological and medical research are reviewed from an historical viewpoint. It is pointed out that early methodological research was directed at the selection of suitable detector substances for radiation (nuclear emulsions) and at the preparation and application of suitable layers of these detectors to biological samples. On the other hand, later research was more concentrated on aspects of the preparation of the biological components of the specimens. In particular, the retention of biochemicals in the tissue sample was studied in detail. Research in the quantification of the emulsion response to α and β radiation paved the way for certain quantitative applications of autoradiography. This has been followed by the derivation of models for the measurement of image spread and the evolution of image analysis methods which allow refined determinations of the specific radioactivity of fine structures taking into account losses and gains of silver grains by image spread.The sum of all these advances is a methodology capable of localizing and quantifying radioactivity and hence marking chemical processes from an organism and organ level down almost to the present limits of anatomical delineatio

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1982.tb00439.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY