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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The major task of biological high resolution SEM and TEM is to provide structural information for correlating structure and function. It is the only methodology with the inherent power needed to observe structures down to molecular dimensions within the context of complex biological systems. Specimen preparation and imaging techniques should therefore be directed towards the preservation and imaging of the smallest significant details in order to fully exploit this unique, integrating feature of biological electron microscopy, complementing the progress of the techniques used in cell biology, biochemistry, and molecular biology.
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PMID:Towards high resolution SEM of biological objects. 129 Jun 66

The peritoneal stomata in sixteen human specimens were studied by SEM, TEM and ODO freeze fracture techniques. In order to prove that the peritoneal stomata are the passage ways by which ascites is absorbed from the peritoneal cavity, animal experiments were performed. The results showed that the peritoneal stomata, which were only found between the cuboidal cells, were formed by the cytoplasmic processes of nearby cells. There were no basement membranes in the peritoneal stomata or the cuboidal cells which formed the peritoneal stomata. Microfilaments were observed in the cuboidal cells. Cytoplasmic processes of mesothelial cells and networks of connective tissue were found in the peritoneal channels. These had networks which formed the floor of each stomata and the roof of each lacunae. We observed that numbers and diameters of the peritoneal stomata were increased in mice with ascites. Red cells and carbonic particles injected into the peritoneal cavity were absorbed by the peritoneal stomata. So the microfilaments of the cuboidal cells, the cytoplasmic processes, and the fiber networks in the peritoneal channels can adjust the absorptive properties of the peritoneal stomata. The peritoneal stomata are an important pathway for draining ascites from the peritoneal cavity.
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PMID:[Study on the peritoneal stomata and absorptive mechanism of ascites]. 129 36

The effects of ozone in low concentrations on animals and human beings were studied. The animal observations included biochemical tests, cellular analysis of bronchoalveolar lavage fluid (BALF) and blood, lung morphological observations by TEM and SEM. The human observations included pulmonary function test, behavior function test, etc. Through three years of study certain sensitivity indices and different threshold concentrations of ozone action have been found, and an environmental health criterion for ozone has been proposed, namely, the average concentration in one hour should not exceed 0.1 mg/m3.
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PMID:[Studies on ozone toxicity and its environmental health criterion]. 130 50

Twenty four patients, who had marked reduction of vision due to secondary-cataract developed after an ECCE, were treated by surgical cleaning of the posterior lens capsule. During this procedure globular secondary-cataract material was removed and collected for morphological examination by SEM and TEM. Fragments of various sizes and shapes, including some with a 'golf ball' structure, were seen; these closely resembled particles frequently found in cataractous lenses. In addition, in 18 patients micro-organisms were found: rod-shaped bacteria, cocci, and in 2 cases yeasts. These findings were the more remarkable because these were clinically quiet eyes with no signs of intra-ocular inflammation and cultures have been persistently negative. We imagine that these bacteria must have entered the eye during the cataract extraction and have settled there without causing an infection.
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PMID:(An)aerobic bacteria found in secondary-cataract material. A SEM/TEM study. 130 16

Lens tissue from a Morgagni cataract was examined by SEM and TEM. For SEM, after prefixation with glutaraldehyde and postfixation with the tannic acid/arginine/OsO4 non-coating (TAO) technique, and for TEM, after prefixation with glutaraldehyde, postfixation with OsO4/K4Fe(CN)6 and poststaining with uranyl acetate/lead citrate. The TAO technique seems to be a particularly suitable postfixation method for the SEM investigation of cataract tissue because of the presence of the protein structures present. The cortical region showed areas of radially, instead of concentrically, arranged lens fibres, degenerated lens fibres with holes (vacuoles), broken ball and socket connections between the lens fibres, and oval or spherical structures varying in size from 0.5-20 microns, the largest resembling a golfball, arising from the cytoplasm of degenerating lens fibres. The smallest, 0.2-0.5 microns, appear to have been expelled from the furrowed lens epithelium.
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PMID:Study of the substructure of the Morgagni and Brunescens cataract with the TAO non-coating technique. Part 1: Morgagni cataract. 130 20

Lens tissue from a Brunescens cataract was prepared for SEM study by prefixation with glutaraldehyde and postfixation with the tannic acid/arginine/OsO4 combination; for TEM study the material was prefixed with glutaraldehyde, postfixed with OsO4/K4Fe(CN)6 and poststained with uranyl acetate/lead citrate. At low magnification, in contrast to the Morgagni cataract, no difference could be seen between the lens fibres in the cortical and nuclear areas. Morphologically, the destruction of the ball and socket system and the development of holes and spherical structures was striking. The latter appeared to have a thin coating and, after fracture, were either empty or showed remnants of material resembling membranes. In sections of the cataractous material, larger vacuoles containing smaller spheres were indistinctly visible.
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PMID:Study of the substructure of the Morgagni and Brunescens cataract with the TAO non-coating technique. Part 2: Brunescens cataract. 130 21

The attachment of Salmonella typhimurium var. copenhagen to the intestinal epithelium of pigeons was studied. After experimental infection, the intestines of both young and adult pigeons were examined in vivo and in vitro. Investigations were carried out by electron and immunofluorescence microscopy. Attachment of the Salmonella strain to duodenal epithelium was established. Following repeated washing after inoculation, bacterial cells could be seen by SEM and TEM in association with the surface structure of the tissue. The adhesive properties of fimbriae, which are also involved in haemagglutination, could be demonstrated.
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PMID:Adhesion of Salmonella typhimurium var. copenhagen in the intestines of pigeons. 135 60

The in vivo effects of the anthelmintics taenifugin, VUFB 14170 and VUFB 15269 on the tegument of Hymenolepis fraterna have been examined by SEM, TEM and cytochemistry. The drugs were given to H. fraterna-infected mice on the 14th day post-infection in a single oral dose of 150, 200 and 200 mg/kg, respectively. By 72 h post-treatment, the drug-induced pathomorphological changes in the tegument indicated that all three drugs had a significant effect. Changes were most pronounced on the brush border and in the intercellular material. On the apical surface, there was blebbing as well as accumulation of membrane fragments over the microthrix tips and erosion of the brush border. The intercellular material was changed in structure, showing increased electron density in some areas and oedema of the intercellular spaces in other areas. There were also fractures of the tegument of variable depth, sometimes reaching to the parenchyma. These results suggest altered tegumental integrity and, occasionally, complete disruption of the selective permeability barrier created by the normal tegument. This suggestion is further supported by the penetration of ruthenium red into some tegumental areas and its distribution into the intercellular spaces, down to the parenchyma. The intrategumental lysosomes also appeared to be significantly activated. There was evidence of autophagy in both distal cytoplasm and tegumental cells. Mature and gravid proglottides were more susceptible to drug damage than those in the anterior strobila and neck.
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PMID:Effects of three anthelmintics on the tegument of Hymenolepis fraterna (Cestoda). 137 75

We used scanning (SEM) and transmission (TEM) electron microscopy to examine ultrastructural changes in the olfactory epithelium (OE) of rainbow trout following unilateral olfactory nerve section. Both ciliated receptor cells (CRC) and microvillar receptor cells (MRC) degenerated and subsequently differentiated from unidentified precursor cells. The following changes took place in fish that were held at 10 degrees C at the stated period following olfactory nerve section: on day 7, MRC and CRC contained intracellular vacuoles; on day 12, the olfactory knobs appeared disrupted; by day 26, olfactory receptor cells were absent from the OE; on day 42, there were receptor cell bodies and a few CRC with short cilia at the apical surface; and on day 55, a small number of both CRC and MRC had differentiated. By day 76, both CRC and MRC repopulated the OE. Degenerative changes in the cytoplasm of the sustentacular cells (SC) and ciliated nonsensory cells (CNC) were observed in the first 26 days following olfactory nerve section, but these cells remained intact throughout the experiment. The degeneration and subsequent differentiation of CRC and MRC supports and extends previous observations that both cell types are olfactory receptor neurons with axons that extend along the olfactory nerve to the olfactory bulb.
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PMID:Ciliated and microvillar receptor cells degenerate and then differentiate in the olfactory epithelium of rainbow trout following olfactory nerve section. 139 69

This paper describes four investigations of the olfactory mucosa of the brown trout: 1) the ultrastructure of the olfactory mucosa as revealed by scanning (SEM), conventional transmission (TEM), and high voltage (HVEM) electron microscopy; 2) light and electron-microscopic investigations of retrograde transport of the tracer macromolecule horseradish peroxidase (HRP) when applied to the cut olfactory nerve; 3) SEM and TEM investigations of the effects of olfactory nerve transection on cell populations within the olfactory epithelium; and 4) ultrastructural investigations of reversible degeneration of olfactory receptors caused by elevated copper concentrations. The trout olfactory epithelium contains five cell types: ciliated epithelial cells, ciliated olfactory receptor cells, microvillar olfactory receptor cells, supporting cells, and basal cells. The ciliated and microvillar olfactory receptor cells and a small number of basal cells are backfilled by HRP when the tracer is applied to the cut olfactory nerve. When the olfactory nerve is cut, both ciliated and microvillar olfactory receptor cells degenerate within 2 days and are morphologically intact again within 8 days. When wild trout are taken from their native stream and placed in tanks with elevated copper concentrations, ciliated and microvillar cells degenerate. Replacement of these trout into their stream of origin is followed by morphologic restoration of both types of olfactory receptor cells. Ciliated and microvillar receptor cells are primary sensory bipolar neurons whose dendrites make contact with the environment; their axons travel directly to the brain. Consequently, substances can be transported directly from the environment into the brain via these "naked neurons." Since fish cannot escape from the water in which they swim, and since that water may occasionally contain brain-toxic substances, the ability to close off--and later reopen--this anatomic gateway to the brain would confer a tremendous selective advantage upon animals that evolved the "brain-sparing" capacity to do so. Consequently, the unique regenerative powers of vertebrate olfactory receptor neurons may have their evolutionary origin in fishes.
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PMID:Ultrastructural neurobiology of the olfactory mucosa of the brown trout, Salmo trutta. 139 70


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