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Query: UMLS:C0276640 (TEM)
 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Seventeen cancers from lung and pleura were studied with scanning, transmission electron, and light microscopy (SEM, TEM and LM). Diffuse mesothelioma mimics bronchioloalveolar carcinoma at LM but shaggy microvilli were found on the cellular surface of the former, and short sprouts densely packed or loosely scattered, on that of the latter. Neolumen formation was found in both. Oat cell carcinoma had a smooth surface with occasional tiny projections and minute surface depressions. The cellular projections of squamous cell carcinoma were quite irregular. Differentiation between diffuse mesothelioma and bronchioloalveolar carcinoma appears feasible with SEM in tissue appropriately fixed either with formaldehyde or glutaraldehyde. The role SEM can play in diagnostic pathology is yet to be explored.
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PMID:A scanning electron microscopic study of diffuse mesothelioma and some lung carcinomas. 19 41

Human deciduous teeth undergoing physiologic root resorption were extracted and fixed with a mixture of formaldehyde and glutaraldehyde and processed for scanning (SEM) and transmission (TEM) electron microscopy, and for acid (ACPase) and alkaline phosphatase (ALPase) cytochemistry. The resorbant organ, rich in odontoclasts, cementoblasts, fibroblasts, and macrophages, formed prominent resorption lacunae in root dentin. SEM observations of resorption lacunae treated with trypsin solution showed islands of newly-formed cementum matrix in part of the resorbing dentin surfaces. Such cementum consisted of bundles of densely-arranged collagen fibrils and, in part, contained forming cementocytic lacunae and canaliculi. Active cementoblasts adjacent to odontoclasts on resorbing dentin surfaces showed cuboidal outlines and were characterized by the presence of numerous cisterns of rough endoplasmic reticulum, well-developed Golgi complexes, secretion granules, and many mitochondria. They sometimes formed a thin layer of cementoid and/or cementum matrix upon the resorbing dentin surface. These cementoblasts had ACPase-positive lysosomes in the cell bodies and exhibited intense ALPase activity along the plasma membranes of whole cell surfaces. These results suggest that, during root resorption, 1) active cementoblasts are present adjacent to active odontoclasts and 2) these cementoblasts are involved in remodeling the resorbing dentin surfaces.
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PMID:Possible role of cementoblasts in the resorbant organ of human deciduous teeth during root resorption. 214 74

The theoretical and practical bases for morphological evaluation of the respiratory system useful for inhalation toxicology are reviewed. For most studies we recommend a comprehensive gross examination followed by in vitro tracheal infusion of a fixative containing both glutaraldehyde and formaldehyde in cacodylate buffer. Lungs fixed in this manner are suitable for LM, SEM, and TEM and lung volumes can be determined. The airway orientation of many lesions and the potential for gradients of damage are considered in the lung sampling plan. While LM of paraffin sections continues to be the basic method for evaluation, the SEM and TEM, especially when ancillary methods are used, provide valuable additional information. The use of backscattered electrons and energy-dispersive X-ray analysis in the SEM provides information concerning the localization and elemental analyses of particles. Cytochemical procedures characterize biological activities of specific cell types and are becoming more widely used. Morphometry permits correlation of quantified structure with physiological and biochemical data.
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PMID:Structural evaluation of the respiratory system. 240 53

We present here a procedure for obtaining high-resolution topographical information about the spatial distribution of antigens at both sides of isolated plasma membranes. HeLa cells grown on coverslips and infected with measles virus served as a model system. Virus glycoproteins appearing at the cell surface were demonstrated by tagging them with rabbit anti-measles antibodies and protein A-gold probes. Cells were stabilized with tannic acid, covered with a cationized coverslip, and then split in potassium-containing buffer. Membranes adherent to the cationized coverslip were fixed in formaldehyde-glutaraldehyde and reacted with mouse monoclonal antibodies against various structural proteins of measles virus. Antibody binding sites at the cytoplasmic surface were visualized either by the antibody bridge method, using normal mouse Ig coupled to gold colloid of different sizes, or by the peroxidase-antiperoxidase procedure. After osmication and critical point-drying, the cytoplasmic surfaces were replicated by platinum-carbon evaporation and examined by TEM without prior cleaning from biological material. This new method permits concomitant localization of antigens present at the inner and outer leaflets of the plasma membrane, and provides high-resolution information about the three-dimensional organization of the cytoplasmic surface.
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PMID:Demonstration of antigens at both sides of plasma membranes in one coincident electron microscopic image: a double-immunogold replica study of virus-infected cells. 329 42

A method using low concentrations of formaldehyde and dithiothreitol was applied to obtain 'right-side out' luminal plasmalemma-derived vesicles from bovine aortic endothelial cells (EC) in culture, and from human umbilical vein and bovine or porcine aortas perfused ex vivo with the vesiculation solution. Vesicle formation and shedding were examined by phase-contrast microscopy and by transmission (TEM) and scanning electron microscopy (SEM). Vesicles showed the characteristic trilaminar pattern of the unit membrane and did not contain cellular organelles. As detected in freeze-fracture preparations, vesicle membrane displayed intramembrane particles and filipin-detectable cholesterol. Like EC plasmalemma, vesicle surface was heavily stained by Ruthenium Red and bound under a normal pattern cationized ferritin and ferritin hydrazide. As indicated by lectin agglutination assays and by ultrastructural cytochemistry, vesicles maintained on their ectodomains glycoconjugates bearing monosaccharides such as N-acetyl-neuraminic acid, beta-N-acetylglucosamine and beta-D-galactose, and expressed 5'-nucleotidase activity. The electrophoretic profiles of externally disposed 125I-labelled polypeptides of vesicles were found to be similar to those of intact EC. Chemically-induced vesiculation appears as a suitable method to obtain EC plasmalemma for studying its composition and functions in various vascular beds.
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PMID:Endothelial cell plasma membrane obtained by chemically induced vesiculation. 359 39

The characteristic morphology of a not intentionally stimulated hyalocyte is described, using TEM and perfusion fixation. The best results were obtained by retrograde perfusion via the abdominal aorta with a glutaraldehyde- and formaldehyde-containing fixative. The cells, situated in the cortical area of the vitreous body, show mostly an indented nucleus, primary and secondary lysosomes, mitochondria, cisterna, clusters of free ribosomes and a Golgi apparatus. Bristle-coated micropinocytotic vesicles can also be distinguished and in some cells a centriole is visible. Sometimes the cells show many cytoplasmic protuberances. Morphologically the majority of those cells can be considered as resting macrophages.
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PMID:Light and electron microscopic studies of the rat hyalocyte after perfusion fixation. 401 Nov 25

In previous studies concerning the morphogenetic movements in the invaginating lens placode of the chick eye, a discrepancy between the TEM and SEM images was observed. With a fixation procedure giving good results in the TEM, certain changes seemed to have occurred in the SEM specimens (opening of apical cell blebs, bubble-like swelling of microvilli). These changes were suspected of being artefacts arisen during processing. Comparing SEM and TEM images of the invaginating lens placode and the surrounding surface applying two different osmolalities of the glutaraldehyde/formaldehyde fixative vehicle, and comparing SEM as well as TEM images with LM images of living embryos using differential interference contrast, yielded to following information. Recent reports in literature that ideal fixation techniques for SEM, certainly those preserving delicate surface structures as apical blebs and microvilli, can differ from those suitable for TEM, were confirmed. Apparently, the cell blebs which can be demonstrated in vivo to be closed, burst during SEM processing as a consequence of a relative hypo-osmolality of the fixative vehicle (a too low effective osmotic pressure). The TEM images appeared to suffer much less from changes in the osmolality of the fixative vehicle. It is suggested, therefore, that the artefacts are brought about by some step specific to the processing for the SEM (E.g. critical point drying).
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PMID:The effective osmotic pressure of the fixative for transmission and scanning electron microscopy. 677 64

The gastric parietal has two characteristic membrane systems. One is the intracellular canaliculus, which is specialized networks of enfolded luminal membrane channels lined with numerous microvilli. The other structures common to all parietal cells are the tubulovesicles or the tubulovesicular membranes, a system of tubules and vesicles. The tubulovesicular compartment is drastically depleted during maximal gastric acid secretion and this is coincident with an increase in the canalicular cell surface membrane. A plausible explanation for this redistribution is the fusion and transfer of tubulovesicular membranes to the plasma membrane. However, for many years there was no convincing evidence of connections between these two membrane systems. The mechanism of the transformation of tubulovesicular membrane into the plasma membrane without demonstrable connections has been an enigma to electron microscopists. Using a recently developed fixation technique for parietal cells [Sugai et al. (1995) Acta Anat Nippon 74:S101], we have investigated the organization of the cytoplasmic membrane systems in the rat resting and tetragastrin stimulated stomachs by ultra-high-resolution scanning electron microscopy (SEM). Gastric mucosae were microwave-fixed in a cacodylate buffer, (334 milliosmoles/kgH(2)O (mOsm)), to which 1.0% glutaraldehyde and 0.5% formaldehyde were added. Specimens examined by TEM of thin sections revealed the cytoplasm packed with tubular membranes similar to images detected by rapid-freeze/freeze-substitution fixation. To render the cytoplasmic membranes visible by SEM, fixed mucosae were treated by the aldehyde-osmium-DMSO-osmium maceration procedure. With much of the cell matrix and filaments removed, SEM revealed numerous 30-60-nm tubules, which formed a meshwork with small cisternae. Vesicles or isolated tubules were not found in adequately macerated parietal cells. The cytoplasmic surface of the intracellular canaliculus was smooth except for round openings representing the bases of macerated microvilli. In favorable sites, connections of the tubular membranes to the canaliculi were clearly visible. Stereo pair views were particularly useful to demonstrate these continuities. Connections between these two membrane compartments suggest the probability of rapid membrane transposition. In this article, the form and distribution of membrane systems of parietal cells in the resting state and after tetragastrin stimulation will be presented and discussed. Special emphasis is made to demonstrate connections between the tubulovesicular system and the intracellular canaliculus.
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PMID:Morphological studies on the translocation of tubulovesicular system toward the intracellular canaliculus during stimulation of the gastric parietal cell. 1070 45

The receptor organs of snakes with "thermal vision" were studied with ultra-high-resolution scanning probe microscopy (SPM) at close to in vivo conditions to elucidate their surface morphology and materials properties critical for prospective biomimetic design of "soft matter"-based infrared (IR) sensors. The surfaces of living tissues were scanned under wet ambient conditions in physiological solution, and the resulting parameters were compared with SPM data obtained for chemically treated (formaldehyde-fixed) tissue in ambient air and TEM studies in high vacuum. We found that the microstructural parameters for the living tissue are similar to ones observed for the formaldehyde-fixed snake tissues. However, previous data obtained from TEM analysis in high vacuum underestimated actual dimensions of surface microstructures. The average spacing of the nanopit array observed within receptor surface areas, which was suggested to play a critical role in selective IR adsorption, was determined to be 520 nm. This value is close to the grating spacing required for efficient reflection of electromagnetic radiation characteristic for sunlight without affecting IR adsorbance.
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PMID:Biological thermal detection in infrared imaging snakes. 1. Ultramicrostructure of pit receptor organs. 1171 29

Preparation and characterization of polymeric particles ultrafine on Hb-SDS-Ag have been reported. (Taking fixed quantity of Hb, SDS to be putting in a beaker, then Ag(NH3)2NO3 solution, pH--12 buffer, n-heptane and iso-amyl-alcohol were added. And fixed quantity formaldehyde, n-heptane and iso-amyl-alcohol were added in another beaker. They were stirred emulsification respectively, both of mixture were mixed in a three-well flask and which were reacted for 1.5 h at 60 +/- 0.5 degrees C. After cooling, the precipitation was separated and washed once and again, it was dried) The structure of surface have been investigated by XRD, TEM and FT-IR for this polymeric ultrafine particles, and size of diameter is about 120 nm. It is shown that Ag+ ion first formed chemical binding with Hb, then reduced to Ag particles and finally collected to a network polymers of coated by Hb.
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PMID:[Preparation and characterization of polymeric ultrafine particles on Hb-SDS-Ag hydrogeles (I)]. 1293 49


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