Electron Microscope Techniques

Rats were anaesthetised by intraperitoneal injection of 30 mg pentobarbital/kg and perfused from the abdominal aorta with 2.5 % glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 7.4), postfixed with 1 % osmium tetroxide in sodium cacodylate buffer and embedded in Epon 812. Sections cut at 50 nm were stained with lead citrate and uranyl acetate. 

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Given the difficulty of obtaining three-dimensional crystals of membrane proteins, it is not surprising that the electron microscope technique is now widely used to study large membrane-bound complexes such as the acetylcholine receptor, rhodopsin, ion pumps, gap junctions, water channels and light-harvesting complexes, which crystallize in two dimensions. 

Qualmann and Kessels have reported the synthesis of carborane-containing lysine dendrimers (123) (Fig. 72), with a better defined number of boron atoms, for use as protein labels in immunocytochemistry using electron microscopic techniques such as electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI).149... 

IMS is a new, developing technique to visualize biomolecule maps in tissue. IMS has opened a new frontier in medicine as well as in clinical applications. Lipids and low-molecular-weight compounds in tissue sections cannot be observed with conventional microscopic or electron microscopic techniques therefore, no distribution map of these molecules in a tissue structure has been described in the scientific literature or in medical textbooks. However, IMS is bringing to light the characteristic distribution map of lipids (Fig. 21.11) this map made a major impact to lipid research. 

Multilayer assemblies of -0.5 pm thickness were built up on quartz plates and the films were characterized in detail using spectroscopic (vis. IR) and electron microscopic techniques. 

The process of infection of lupine nodule cells by Rhizobia was examined by the thin-section electron microscopic technique, as well as the freeze-fracture technique. Different membranes such as infection thread membranes, peribacterioid membranes, plasma membranes, membranes of cytoplasmic vesicles, and membranes of the Golgi bodies and ER were stained with uranium-lead, silver, phosphotungstic acid, and ZIO (31). ZIO stained the membranes of the proximal face of the Golgi bodies and endoplasmic reticulum. ZIO staining has given good contrast in thick sections such as a cotyledon cell, a root cell, and an aleurone layer for ER, dictyosomes cisternae, mitochondria, and nuclear envelopes (17,32-37). 

Stelzer R, Lehmann H. Recent developments in electron microscopical techniques for studying ion localization in plant cells. Plant Soil 1993 155 33-43. 

Figure 7.26 EMSI images from a Pt(l 10) surface during CO oxidation at 480 K and total pressure in the 10 mbar range. The image represents an area about 1 mm wide. Electron microscopic techniques such as PEEM would be able to image at higher resolution, but cannot be applied at these relatively high pressures (from Ertl and Rotermund [75]).

Size analyses are commonly carried out by mixing the pigment powder with an organic solvent or with water and adding appropriate surfactants to enhance the dispersibility of the powder. Aqueous dispersions frequently undergo size separation in ultracentrifuges, while organic solvents are more appropriate for electron microscopic techniques. 

Tissues are being examined by conventional histologic and electron microscopic techniques. An atlas of normal gross and microscopic mussel structure is being prepared using animals col-... 

Electron microscopic techniques can be used in order to visualize the architecture of the network. We have adapted (P. Favard, N. Favard, M. Djabourov, J. Leblond, to be published) a method recently proposed by Heuser (9) (1978), for the observation of biological cells and tissues. ... 

Transmission electron microscopy (TEM) can provide valuable information on particle size, shape, and structure, as well as on the presence of different types of colloidal structures within the dispersion. As a complication, however, all electron microscopic techniques applicable for solid lipid nanoparticles require more or less sophisticated specimen preparation procedures that may lead to artifacts. Considerable experience is often necessary to distinguish these artifacts from real structures and to decide whether the structures observed are representative of the sample. Moreover, most TEM techniques can give only a two-dimensional projection of the three-dimensional objects under investigation. Because it may be difficult to conclude the shape of the original object from electron micrographs, additional information derived from complementary characterization methods is often very helpful for the interpretation of electron microscopic data. 

H. Ngo, G.J. Mount, M.C.R.B. Peters, A study of glass-ionomer cement and its interface with enamel and dentin using a low-temperature, high-resolution scanning electron microscopic technique. Quintessence Int. 28 (1997) 63-69. 

Chemical and electron microscopic techniques have been used to verify the presence of an adsorbed layer surrounding emulsion globules. Proteins are examples of hydrocolloids that exhibit... 

Aerosol Heterogeneity. The variation of the chemical composition from particle to particle within an aerosol size class has been probed in a number of ways. Single-particle chemical analysis has been achieved by using the laser Raman microprobe (25) and analytical scanning electron microscopy (26). With the electron microscope techniques, the particle can be sized as well as analyzed chemically, so the need for classification prior to sample collection is reduced. Analyzing hundreds to thousands of particles provides the information necessary to track the particles back to their different sources but is extremely time consuming. 

Most electron microscopic studies of BBB endothelial cells suggest the presence of relatively few observable endocytic vesicles in the cytoplasm of these cells compared with other endothelia. For example, the BBB contains only a fifth to a sixth of the endocytic profiles seen in muscle capillary endothelia [54], although they may increase to comparable levels with inflammation of the BBB [55]. However, when a comparison is made of the ability of capillary endothelia in a variety of different tissues to trancytose protein, there is a very poor correlation between the protein permeability of a microvessel and the number of observable endocytic profiles [54]. Brain capillary endothelia are very thin cells, the luminal and ablum-inal membranes only being separated by some 500 nm or less (5000 A), and caveoli are 50-80 nm in diameter and thus the events of transcytosis may be difficult to capture within the cell using conventional electron microscopical techniques. 

Shukla, D. D. and Gough, K. H. (1983) Characteristics of the protein A-immunosorbent electron microscope technique (PA-ISEM) for detecting plant vims particles. Acta Phytopathol. Hung. 18,173-185. 

Leppard, G.G. (1992) Evaluation of electron microscope techniques for the description of aquatic colloids. In Environmental Particles (eds Buffle, J. and van Leeuwen, H.P.), Vol. 1. Lewis Publishers, Chelsea, MI, pp. 231-289. 

The flux of horseradish peroxidase from the mucosal to serosal sides is jnwsrimiuj hy in vital KinmmenN jn slrinnpJ anlrffijih intestinal epithelium. Through enzymology and electron-microscopic techniques the intestinal uptake is shown [50],... 

In high vacuum processes, which are related to our subject only by electron microscope technique, the rate at which a substance evaporates has an ultimate limit depending on the number of molecules having momentarily enough energy to break away. Thereafter, they follow a straight line until they collide with an object. When a substance evapo-... 

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