摘要:

SummaryTwo modifications to the conventional procedure of cross‐correlation are described, widely used for establishing the relative alignment of the members of a set of images from which a higher resolution or more interpretable restoration is sought. Both achieve a high and sharp peak in circumstances where the conventional peak is too ill defined to be recognizable; neither involves significant additional computation time. The more general method requires rough knowledge of the imaging conditions, but a variant applicable to images with axial resolution has no such requirement. In addition, a least‐squares procedure is presented for achieving an optimum compromise between many pair‐wise displacement measurements, preventing the accumulation of alignment errors across a set of i

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03449.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe lateral and depth resolution of nonlinear microscopy was studied systematically. Nonlinear microscopy can be classified into several categories depending on the coherence properties of the process that generates the imaging signal from the illuminating light, on whether a single‐ or a two‐beam geometry is used, and whether the optical setup is Type I or Type II. An evaluation of the imaging equations shows that (i) lateral and depth resolution improve with increasing nonlinearity, (ii) the differences between coherent and incoherent imaging diminish, and (iii) nonlinear imaging allows depth discrimination in Type I microsc

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03450.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe use of fully automated data collection methods for electron tomography allows a substantial reduction in beam dose. The goal has been to develop new protocols for data collection defining optimal approaches for maintaining data self‐consistency and maximizing the useful resolution of the reconstruction. The effects of irradiation and post‐cure microwaving were examined for a variety of embedding media (Epon, Epox, Lowicryl) in order to quantify beam damage with the goal of identifying the most beam stable embedding medium. Surprisingly, the substantial dose reduction made possible by automated data collection did not result in a significant decrease in specimen shrinkage even for samples stabilized by preirradiation. We believe that the accelerated shrinkage is a direct consequence of the stroboscopic illumination patterns inherent to automated data collection. Further‐more neither the choice of embedding resin nor microwave post‐curing greatly affected shrinkage. Finally, cryogenic data collection was investigated as a means to minimize the effects of secondary radiation damage. Minimal preirradiation coupled with low‐temperature automated data collection greatly reduces shrinkage and should result in high‐quality data for three‐dimensional re

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03451.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryA novel method is described for the estimation of the mean cell volume of cell populations grown in suspension. The cells are filtered onto a nitrocellulose filter to form a cylindrical pellet which is embedded in epoxy resin. Using estimates of pellet height and radius, the number of cells in the pellet and of the volume density of the cells in the pellet, it is possible to produce an unbiased estimate of the mean cell volume. This method is compared, using cell suspensions of the blood parasiteTrypanosoma brucei, with mean cell volume estimation using a Coulter channellizer. A Coulter channellizer was also used to compare the mean cell volume of living trypanosomes with that of aldehyde‐fixed populations, and the values obtained were compared with those obtained using the new method. The estimated mean cell volume of aT. bruceiclone was used to derive values from volume densities obtained by point and intersection counts for the absolute volumes of the flagellar pocket, the nucleus, and endocytic organelles containing internalized horseradish peroxidase and transferrin‐gold after 30‐min incubations at 310 K. Estimated values for the surface area of the flagellar pocket and the surface area of a cell were also obtained. From known data on the total amount of variant surface glycoprotein molecules per cell and the known packing density of membrane proteins, it was estimated that approximately 80% of the molecules must reside in intracellular compartments. It was estimated that the equivalent of 5% of the surface membrane may be internalized per minute, an amount which is almost the size of the entire flagellar pocket mem

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03452.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryObjective grading of breast cancer by morphometry has been suggested for improving the precision of the prognostic prediction. However, the tissue components evaluated might be influenced by variations in the processing, reducing the clinical value. In the present study, the impact of the period of fixation, of the acidity of the fixative and of the embedding medium was investigated by allocating tissue samples from 27 surgical breast cancer specimens systematically randomly to different modes of processing. The volume‐weighted mean volume of cancer cell nuclei, v̄V(nuc), was estimated using the method of point‐sampled intercepts on vertical sections. In addition, estimates of the mean nuclear profile area, āH(nuc), the nuclear volume fraction, VV(nuc), the nuclear profile density,ND, and the mitotic profile frequency,MF, were obtained.The quantitative histopathological estimates were stable with respect to the investigated variables of the tissue processing. No significant differences were found when comparing the estimates obtained in samples from five tumours fixed in formalin at pH 5·0, 6·0, 7·0, 7·4 and 8·0, respectively. Similarly, no significant correlations between the estimates and the period of formalin fixation (24 h, 3 days and 3 months) were found in samples from five other tumours. However, the v̄V(nuc) was 13% larger (2p= 0·004) and the meanND17% smaller (2p= 0·04) in hydroxyethyl‐methacrylate‐embedded samples from 17 tumours as compared to paraffin‐embedded samples. Thus, the shrinkage observed in paraffin seems to affect nucl

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03453.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryA series of three‐dimensional image analysis tools are used to measure the three‐dimensional orientation of nuclei of myocardial cells. Confocal scanning laser microscopy makes it possible to acquire series of sections up to 100 μm inside thick tissue sections. A mean orientation vector of unit length is calculated for each segmented nucleus. The global orientation statistics are obtained by calculating the vectorial sum of the nuclear unit vectors. The final orientation is expressed by a mean azimuth angle, an elevation angle and a measure of the angular homogeneity. The method is illustrated for two different regions of the myocardium (interventricular septum and papillary muscle) of a normal human fetal heart. This quantitative method will be used to assess and calibrate the information provided by polarized light micros

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03454.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryIn arterioles of the lung the intravascular blood pressures are lower than in comparable vessels in the systemic circulation and the arteriole walls are thinner. Therefore, it is very difficult to distinguish between arterioles and venules of the same size using scanning electron microscopy. This study describes a novel application of latex microsphere perfusion and scanning electron microscopy which distinguishes between pulmonary arterioles and venules on the basis of endothelial cell morphology. Microspheres, 90 and 45 μm in diameter, were perfused into the arterial side of the pulmonary circulation of guinea‐pig and rabbit lungs. Scanning electron microscopy of the arterioles on both sides of the lodged microspheres indicated that the endothelial cells are spindle shaped. In contrast, the endothelial cells of equal diameter venules are polygonal. Furthermore, the nuclei of the arteriolar endothelial cells were significantly (P= 0·019) narrower than those of endothelial cells in venules of equal diameter. Finally, it was observed that the differences between arteriole and venule endothelial cells persisted distally to the capillar

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03455.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe axial response of a basic confocal microscope is determined when the sample is a thick cylindrical or tubular structure. The response from the back wall of the cylindrical sample is split into two separate signals due to basic aberration or astigmatism effects.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03456.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe effect of two commonly used tissue clearing methods on the morphology of vascular casts formed by Microfil, a silicone rubber injection compound, was investigated. Microfil undergoes extreme shrinkage when the casted tissue is cleared by the alchohol‐methyl salicylate clearing technique. No shrinkage is observed when the alternative glycerin clearing method is used. The alcohol‐methyl salicylate clearing technique should be avoided in studies employing Micro

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03457.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb03458.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY