摘要:

SUMMARYIn this tutorial article, some basic concepts of image formation in conventional transmission microscopy are reviewed, particular attention being given to the meaning and role of partial coherence.The application of these ideas to scanning transmission microscopy is also discussed.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03962.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYThe effect of various fixatives on the path of the fracture plane during freeze‐fracturing was studied in red blood cells. In unfixed cells the fracture plane ran between the leaflets of the plasma membrane (membrane‐fractured cells) in 66% of the cells and across the cells (cross‐fractured cells) in 34%. Formaldehyde fixation greatly increased the proportion of cross‐fractured cells (up to 80%) and osmium tetroxide acted in a similar manner (up to 90% cross‐fractured cells). With glutaraldehyde fixation, small, smooth patches of cross‐linked material were often seen on the convex (A) fracture faces. Holes were found on the corresponding concave (B) fracture faces. Uranyl acetate had no effect on the fracture plane or distribution of particles. Thus osmium and formaldehyde might be a useful means of altering the fracture plane of membranes (e.g. in bacteria or envelop

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03963.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYA procedure is described for determining the joint distributionLv(r, ø, θ) of the radii (r) and orientation (ø, θ) of a filamentary structure from measurements on a single section. For tubular filaments it is also possible to determine the wall‐thickness distribution. The following assumptions are made: (1) that the filaments have a circular cross‐section; (2) that the length and radius of curvature of the filaments are large compared with their radii.The analysis is also applicable to transmitted images if the thickness of the slice is small compared with the average radius of the fi

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03964.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYOptical shadowing offers the possibility of combining the high resolution of the transmission electron microscope with the study of surface detail, commonly investigated with the scanning electron microscope.Image formation in this mode of operation is treated according to the formalism of Fourier optics, where we consider the objective aperture to be a spatial filter in a coherent imaging system. For a simple specimen it is shown theoretically as well as experimentally that the image appears to be a shadowed representation of the object, when the objective aperture is moved off centre so that half of the zero‐order diffraction spot is blocked. A computer model is presented that gives a faithful description of the theoretical and experimental image intensity profile for the simple test specimen. The computer model is then used to predict image profiles for more complicated (or more realistic) specimen profiles. The calculations show that a certain ambiguity arises when one attempts to interpret the optically‐shadowed image profiles: it would be difficult to distinguish the three different edge contours based only on their appearance in this mode of operation. As with any other EM technique, then, results obtained with optical shadowing must be compared with the results obtained using the oth

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03965.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYThe distribution of sodium antimony dimercaptosuccinate in the helminth parasiteSchistosoma monsoniwas determined using a transmission electron microscope (TEM) fitted with an X‐ray non‐dispersive analysis system. Both Araldite and cryosections of the parasite were examined.The drug was found to have a marked effect on some cells of the ovary and vitelline gland and it was within these cells that the drug was demonstrated. Within the vitelline cells the drug was confined to the vitelline droplets and the analysis of both Araldite and cryosections confirmed that the absence of drug from other tissues was genuine and not due to loss during processing. Maximum retention of elements was achieved in cryosections and this type of material also enabled one to distinguish elements genuinely associated with the tissues from those present in the Araldite matrix.The combination of X‐ray analysis with TEM and cryosectioning has provided a most valuable tool for the study of drug distribution at tissue and subcellular levels and also enabled the elemental characteristics of the tissue at the precise drug locus to be deter

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03966.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYThe design and operation of a simple, semi‐automatic video system for the analysis of geometric parameters of microscopic specimens is described. The system consists of standard video equipment and a custom built Electronic Integrator. The video signal from a camera attached to a microscope is mixed with the video signal from a second camera focused on a drawing board. A contour outline of the specimen to be analysed is drawn with the aid of a video monitor display of the combined images. The contour image is passed into the Electronic Integrator and analysed automatically. Logic circuitry in the Electronic Integrator permits analysis of complex contours independent of their orientation in the video raster. The area or volume of complex, overlapping specimens with restricted grey scale range can be rapidly analysed. The Electronic Integrator also is suitable for densitometric and specimen motion analyse

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03967.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYA prism‐mirror‐prism electron energy filter has been inserted into a fixed beam transmission electron microscope. The insertion of the filter has not degraded the spatial resolution of the microscope, while providing an energy resolution of 2.5 eV. The filter greatly reduces the chromatic aberration of the images, increasing resolution in dark field and contrast in bright field. Images of bacteriophage T4 and of polyoma virus indicate that thick unstained and unshadowed biological specimens can now be observed at high resolution in dark field. In addition, the increased contrast and definition observed in bright‐field images of conventional liver sections suggest that it should be possible to obtain sufficient contrast from stains containing atoms of lower atomic numbers than those employed at pr

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03968.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYA definite correlation and continuity has been obtained between the observations of ultrastructure of collagen fibres teased from rat tail tendon, by two different techniques; (1) polarizing optical microscopy and (2) scanning electron microscopy (SEM). The stereographic micrographs of the fibres taken by SEM shows that the surface periodicity is of the planar form and is similar to the model proposed by Diamantet al. (1972) from polarizing microscopic observations.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03969.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SUMMARYA simple and inexpensive device is described which allows the monitoring of structural vibrations present in ultramicrotomy laboratories. Information obtained with this device is described.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03970.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Book reviewed in this article:Scanning Electron Microscopy Systems and Application 1973. Ed. by W. C. Nixon.The Fine Structure of Cotton—An Atlas of cotton microscopy. By Inez V. deGruy, Jarrell H. Carra and Wilton R. Goyne

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1974.tb03971.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY