共查询到20条相似文献,搜索用时 10 毫秒
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Three-dimensional (3-D) information on nervous tissue is essential for the understanding of brain function. Especially, 3-D synaptic analyses on serial ultrathin sections with transmission electron microscopy (TEM) have contributed to the knowledge on neural plasticity associated with various pathophysiological conditions. The 3-D reconstruction procedures, however, not only require a great amount of expertise but also include time-consuming processes. Here, we carried out computer-assisted 3-D reconstruction of parallel fibre-Purkinje cell synapses based on 250 nm serial sections using high-voltage electron microscopy (HVEM). The 3-D synapse models were constructed more efficiently and rapidly compared with conventional serial TEM reconstruction. This result suggests that 3-D reconstruction with thicker sections and HVEM is a useful method to study synaptic connectivity. 相似文献
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Here we describe a computer-assisted method which, based on conventional transmission electron microscopy, renders simulated high-voltage electron micrographs. We perform arithmetic minimum filtering on stacks of aligned serial transmission electron microscopic images. In this way, the structural information of the separate images is fused into one compound image that highlights organization patterns otherwise easily overlooked or impossible to comprehend. Our method, like high-voltage electron microscopy, offers the possibility to build stereo-pairs for high-resolution three-dimensional analysis of tissue layers 1-2 microm thick. The use of background elimination and the development of a depth enhancement routine improved the three-dimensional effect and facilitated the analysis of the interior of objects. As an example, we use the method to display the distribution of axonal organelles at nodes of Ranvier and the shape and contents of a highly branched hippocampal dendritic spine. 相似文献
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Three-dimensional reconstruction was performed using scanning electron micrographs of serial semi-thin sections of Epon embedded specimens. Connective tissue in a rabbit ear chamber was fixed in glutaraldehyde and osmium tetroxide, and then embedded in Epon. One-microm-thick serial sections were cut with a diamond knife, mounted on glass slides and stained with toluidine blue. After observation with a light microscope, the sections were ion-etched with an ion-spatter coater. Following double staining with uranyl acetate and lead citrate, the consecutive sections were ion-coated with platinum. Each serial section was photographed with a scanning electron microscope. Profiles of a blood vessel and fibroblasts were digitized with a computer and computer reconstruction of the blood vessel was performed. Three-dimensional reconstructions showed that the newly formed blood vessel was a cylinder-like, bare endothelial tube with a rather smooth outer surface. Fibroblasts were situated around the endothelial tube. Several openings were found in the endothelial tube, suggesting the morphological feature of high permeability and fragility in newly formed blood vessels. The availability of three-dimensional reconstruction from scanning electron micrographs of serial semi-thin epoxy resin sections was discussed; structures of interest can be reconstructed (1) quickly and easily, (2) without skilful techniques, and (3) almost at the level of ultrastructure. 相似文献
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Three-dimensional ultrastructure of rat acellular glomerulus by scanning electron microscopy 总被引:1,自引:0,他引:1
H Makino 《Journal of electron microscopy》1988,37(6):294-304
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Canali C. Giannini M. Scorzoni A. Vanzi M. Zanoni E. 《Solid-State Circuits, IEEE Journal of》1988,23(2):597-603
The scanning electron microscopy (SEM) technique for the study of the local sensitivity to latch-up of CMOS integrated circuits is discussed. The technique is independent of a particular electric firing mechanism of latchup and does not require in-depth electrical characterization of the IC before the analysis. The electron beam in the SEM is adopted as a localized current injector, and the injected carriers are used to induce the latch-up state rather than to visualize its paths. A minicomputer-based system drives the beam position and automatically blanks the beam if the scan path has to cross areas which should be protected from charge injection. An example of application is described.<> 相似文献
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Ghosh K Gangodkar S Jain P Shetty S Ramjee S Poddar P Basu A 《Journal of electron microscopy》2008,57(3):113-118
Thrombocytopenia is frequently associated with dengue virus infection. Host factors such as anti-platelet immunopathogenic processes have been implicated in the origin of dengue-associated thrombocytopenia but the role of dengue virus in directly interacting with platelets and altering their hemostatic property remains incompletely understood. In the present study, we examined the effect of dengue 2 virus on the morphology and physiological activation profile of normal human platelets using atomic force microscopy, electron microscopy and flowcytometry. Platelets obtained from healthy donors were exposed to a cell culture-adapted 10(4) LD(50) dengue 2 virus isolate in vitro and the subsequent effect on morphology and activation biology studied. Our results show that dengue 2 virus exposure at doses comparable to natural viremic states in human infections can activate platelets with an increase in P-selectin expression and fibrinogen-binding property. Atomic force, scanning and transmission electron microscopy also showed typical activation-related morphological changes such as altered platelet membrane architecture, degranulation, presence of filopodia and dilatation of the open canalicular system in the dengue 2 virus-exposed platelets but not in the controls. Importantly, Japanese encephalitis virus exposure at the same dose did not activate platelets or show any morphological changes. Our findings suggest that dengue 2 virus may directly interact with and activate platelets - an event that might be important in the origin of dengue-associated thrombocytopenia. Detailed molecular characterization of this effect might provide key knowledge toward better prophylaxis of the hemostatic complications of dengue disease. 相似文献
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T Katsumoto M Asanaka S Kageyama T Kurimura K Nakajima A Noto H Tanaka R Sato 《Journal of electron microscopy》1990,39(1):33-38
The techniques of pre- and post-embedding immunocolloidal gold electron microscopy were tested for their usefulness for analyzing the morphogenesis of human immunodeficiency virus (HIV) strain LAV employing U-937 cells persistently infected with the virus (U-937/LAV). By both techniques the following results were obtained. (1) Budding process was restricted to a localized area at the membrane adjacent to the Golgi apparatus. (2) The distribution of viral envelope antigens was restricted to the electron-dense crescent structures on the cell surface. (3) Virions released from the cells could be classified mainly into 2 categories: virions with doughnut-shaped cores or with conical cores at the center of the particles. And p24 proteins localized on the thick electron-dense cores of both types. These findings support the idea that pre- and post-embedding immunogold electron microscopy is very useful for studying the morphogenesis of viruses. 相似文献
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Using single particle images taken by electron microscopy, pH-dependent conformational changes of human serum albumin were investigated. Despite the noisy particle images of negatively stained serum albumin (67 kDa), our novel algorithm for automated particle picking and reference-free classification resulted in the appropriate grouping of the particle images. Iteratively aligned particle images in the same group provided recognizable image features for individual groups. In a pH 7.0 study, monomer images were consistent with an available crystal structure model; the dimer images were separated into different classes. At pH 3.5, the monomer images were similar to those at pH 7.0; slight differences included a small number of elongated conformations and increased population of larger multimers. Our images were also compared with projection images of an atomic model from crystallography, and demonstrated consistency of the molecular conformation both at pH 7.0 and pH 3.5. Our classification method was effective in discriminating monomers from a mixture of different conformations of the protein, enabling the study of the conformational dynamics of small proteins, using the atomic model as a reference. 相似文献
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精确给出电离层的实时变化信息对现代通信和卫星导航等系统可靠应用具有非常重要的意义.为提高电离层经验模型电子密度的输出精度,提出了一种基于地基GNSS和COSMIC掩星数据吸收的三维电离层电子密度重构的新方法.以最新版国际参考电离层模型IRI-2016为背景模型,选择IG指数与Rz指数作为驱动量,采用Brent算法分两步实现了地基GNSS和COSMIC掩星数据的吸收.与欧洲区域8个垂测站实测数据的对比表明:数据吸收后模型重构的电离层NmF2的绝对平均误差和标准差分别下降了33%和29%;电离层hmF2的重构误差则分别下降了约55%和30%.对比结果验证了所提方法的精度和有效性. 相似文献
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Mitochondria in all eukaryotes are essential organelles responsible for adenosine triphosphate synthesis, calcium homeostasis and steroidogenesis. Because the structure and distribution of mitochondria are highly diverse depending on their function and cellular conditions, it is important to develop a rapid and accurate method to assess their morphology. In this study, we visualize whole mitochondria in cultured cells using high-voltage electron microscopy (HVEM). Compared with conventional transmission electron microscopic approaches, the present method does not require thin sectioning and thus requires less time for image acquisition and processing. Furthermore, compared with fluorescence-based light microscopic approaches, our method provides more accurate size information. Thus, we propose that HVEM is a useful tool for rapid and accurate analysis of mitochondrial morphology and distribution in a cell. 相似文献
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利用冷冻电镜单颗粒三维重建方法获得分辨率1.5nm家蚕质多角体(BmCPV);2.5nm,中蜂囊状幼虫病病毒(CSBV);1.4nm,伊蚊C6/36细胞浓核病毒(C6/36DNV)的三维结构体数据,对三维结构数据进行了数据归并,并找到对显示细节较为敏感的向量维度,用表面显示方法对病毒体数据进行三维显示,用基于空间的方法完成了任意区域的交互分割。显示时间和信噪比与原有显示方法有了提高。病毒表面细节和轴上突起清晰可见。所分割的部分结构准确完整,并可以对所分割的部分进行量化分析。为冷冻电镜单颗粒重构提供了新的三维可视与分析方法。 相似文献
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针对距离选通激光主动成像二维切片图像无法提供远距离目标全面空间位置信息的问题,提出了采用阈值法截断灰度级曲线与互相关法提取距离信息相结合的算法对远距离目标进行高精度三维重建。首先,利用阈值法剔除实测灰度级曲线中零值点,从而消除对后续互相关法计算距离值的影响;然后,将每一像素点实测截断灰度级曲线与理想灰度级曲线进行互相关,利用各像素点相关峰值对应的延迟时间推算各点距离值,并结合成像系统参数计算每一像素点的三维坐标;最后,对距离1.2 km处凉亭切片图像进行处理,得到了凉亭目标的三维图像。 相似文献
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肽泡的电子显微镜观察 总被引:1,自引:0,他引:1
本文用电子显微镜方法研究肽泡的形态结构及其特性。结果表明,肽泡大小不等,泡壁由厚度不均一且电子致密度较高的丝状物组成,轲与兔红血球碎片自然重组成双分子层结构,肽泡的包裹特性,有可能使之成为一种良好的药物载体。 相似文献
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A laser transillumination tomographic system, using red and near infrared lasers, to obtain cross-sectional images of human breast phantoms and human hand is proposed. The scanning assembly is consisting of upward, downward, rotational and pitch movements. The phantoms, made of paraffin wax, agar gel, and milk placed in a glass model, are embedded with abnormalities like blood, water, solid objects, and tissues. By illuminating the phantoms at various heights by either red or infrared laser the projection data are collected. Based on 64 projections the tomogram of each section is constructed. By volume visualization procedure applied to the tomograms the objects of varying composition embedded within the phantoms are detected and their size, shape, and location depth are determined. The cross-sectional image of a human hand obtained by this procedure further shows the possibility of application of this technique for imaging of organs. 相似文献
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水生动物病毒的电镜和荧光显微镜观察 总被引:2,自引:0,他引:2
应用透射电镜和荧光显微镜对三种水生动物病毒粒子形态、病毒感染细胞的超微结构变化及亚细胞定位进行比较和研究。负染电镜观察显示:鳜鱼弹状病毒(SCRV)粒子呈典型的子弹状形态,长约76~118 nm,直径约29~52 nm;鲈鱼呼肠孤病毒(LJRV)粒子呈正二十面体结构,具有双层衣壳,直径约70~80 nm;蛙虹彩病毒(RGV)粒子呈正二十面体结构,具有囊膜,直径大小约150 nm。超薄切片观察表明,宿主细胞的基本结构遭到不同程度的破坏,成熟病毒粒子分布在胞质中或以出芽的方式释放到胞外,且RGV增殖后在胞质中聚集形成晶格状结构。免疫荧光观察进一步显示,RGV感染细胞后能产生多个直径大小不一的包涵体。本研究结果有助于了解和认识水生动物病毒的超微形态特征、复制过程及致病机理。 相似文献