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Results for “scanning electron microscope”

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At least 811 records · Page 45Linked to original sources

PubMed1975

Nature of deposits in a tubular membrane oxygenator after prolonged extracorporeal circulation: a scanning electron microscope study.

Although silicone fibers are among the most compatible with tissue and blood, numerous deposits are observed after their prolonged usage in a capillary membrane oxygenator, even when the blood has been properly heparinized. The scanning electron microscope (SEM) study shows that the morphology of these deposits varies greatly, depending upon the part of the unit from which the sample is taken. The area close to the inlet is the most severely affected. The outlet zone is affected to a lesser degree, and the areas in between are only slightly affected.

Animals↗

PubMed2004

A scanning electron microscope examination of silver cones removed from endodontically treated teeth. 1972.

Twenty-five silver cones were removed from teeth which had been treated endodontically from 3 months to 20 years previously. Examination by the scanning electron microscope revealed that these cones were moderately to severely corroded. The corrosion patterns were described as ranging from pitting to deep crater formation with globular or spherical agglomerations. Examinations with the electron probe showed sulfur peaks on the corroded portions of the cones. X-ray diffraction analyses indicated that the chemical compounds formed were silver sulfides, silver sulfates, silver carbonates, and silver amine sulfate amide hydrates. Tissue culture studies indicated that the corrosion products were highly cytotoxic. The mechanisms for the formation of the corrosion products have been postulated as being due to plastic deformations and metal transfer to the silver cones, plus contact of the silver with tissue fluids.

Corrosion↗

PubMed1989

Scanning electron microscopic study of periendothelial cells of the rat cerebral vessels revealed by a combined method of corrosion casting and KOH digestion.

A combined method of corrosion casting and KOH digestion was used for the scanning electron microscopic (SEM) observation of the external walls of the blood vessels running on the surface and in the parenchyma of the rat cerebral cortex. The plastic resin which was preliminarily injected into the cerebral vessels reinforced the preservation of the vessel walls during the chemical digestion. Using the present method, the walls of blood vessels running on the surface and in the parenchyma of the cerebral cortex were clearly seen with SEM. The arterioles showed a rich arrangement of smooth muscle cells embracing the external surface of the endothelia, and the venules had sparse, flat smooth muscle cells. The capillaries were surrounded by many pericytes which were extremely similar to those seen in the other organs of the animals. There were observed two different kinds of pericyte. One type of the pericytes in the present specimens extended very long cytoplasmic processes parallel to the long axis of the capillaries. Another type of the pericytes had relatively short, broad and flat cytoplasmic processes radiated to embrace the capillary walls. The former was frequently seen in the capillaries on brain surface and in the parenchyma, whereas the latter was relatively rare. The availability of the present method was also discussed in comparison with the previous descriptions.

Animals↗

PubMed1976

Scanning electron microscope studies of sea urchin fertilization. I. Eggs with vitelline layers.

The surface coats of sea urchin eggs and the events of fertilization which take place on these surfaces were examined with the scanning electron microscope (SEM). Gametes of Stronglyocentrotus purpuratus and Lytechinus pictus were considered in detail; eggs of seven other echinoids were examined for comparative purposes. Jelly coats, preserved by varying the pH of fixation, were found to vary in morphology and solubility properties between species. The vitelline layers of the nine echinoids are characterized by arrays of projections which are impressions of cytoplasmic microvilli in the vitelline layer. After sperm bind to the egg surface via the acrosomal process, fine filaments, apparently an egg response to insemination, further connect some sperm heads and tails to the egg. The cortical reactions spread out as a wave from where the fertilizing sperm fused with the egg; separation of the vitelline layer proceeds as a smooth wave from S. purpuratus eggs and as a series of localized separations in L. pictus eggs. The fertilization membranes of S. purpuratus and Allocentrotus fragilis zygotes are expanded replicas of their respective vitelline layers, suggesting that fertilization membranes are formed by an unfolding of the vitelline layer.

Animals↗

PubMedDate not supplied

Microvascular anastomosis: a scanning electron microscopic study.

The single most important factor determing the patency of a microvascular anastomosis is the surgical precision with which it is performed. Inaccurately placed sutures, damage of the intima, exposed media and adventitia, and stenosis of the lumen at the site anastomosis all contribute to decreased patency rates. The first 50 consecutive microvascular anastomoses performed by a single microvascular surgeon were analyzed in vivo and with the scanning electron microscope. The frequency and significance of various technical errors are discussed. Scanning electron microscopy is recommended as a convenient and quick technique for assessing the evenness and accuracy of intimal apposition in microvascular anastomosis.

Animals↗

PubMed1998

[Observation on the surface characteristics of the leaves of Dysosma and its related genus by scanning electronic microscope].

OBJECTIVE: To observe the surface characteristics of leaves of Dysosma and its related genus by SEM for identification. METHOD: Leaf surface characteristics of seven species of Dysosma and tow species of its related genus were observed by scanning electronic microscopic method. RESULT: The leaf surface characteristics of upper epidermis and lower epidermis of the nine plants are different from each other. A key and illustrations were listed. CONCLUSION: The leaf surface characteristics observed by SEM can be used for identification of Dysosma and its related plants.

Magnoliopsida↗

PubMed2002

[Study of the insoluble remainder of human gallstones by scanning electron microscope and Fourier transform infrared spectrum].

The insoluble remainder of brown pigment and mixed gallstones which were dissolved with chloroform, ethanol, ether, and hydrochloric acid were studied by Fourier transform infrared (FT-IR) spectrum and scanning electron microscope. It was found that bilirubinate salts, proteins, fatty salts, phosphate and calcium carbonate are the main components in the insoluble remainder of gallstones. The secondary structure of proteins in brown pigment gallstones may be predominated by alpha-helix. The microstructure of proteins in brown pigment stones is membranous, phosphate and bilirubinate salts were trapped within the membranes. The relationship between the insoluble components and formation of gallstones was discussed.

Bilirubin↗

PubMed1983

Scanning electron microscopic studies of adverse effects of ammonia on tracheal tissues of turkeys.

Effects of 10 and 40 microliter of NH3/L of air (10 and 40 ppm) on the tracheal tissues of turkeys were examined under the scanning electron microscope. Turkeys maintained in the presence of either level of NH3 had deterioration of their normal mucociliary apparatus after prolonged exposure. Excessive mucous production, matted cilia, and areas of deciliation in the tracheal tissues were detected in birds exposed to NH3 concentrations as low as 10 microliters/L. The tracheal tissues of birds not exposed to NH3 appeared normal. The implications of respiratory tract damage caused by NH3 are discussed.

Ammonia↗

PubMed1984

A scanning electron microscopic study on the microflora of chronic pericoronitis of lower third molars.

In nine cases of chronic pericoronitis of lower third molars, the affected teeth were carefully removed with the follicles in situ and prepared for scanning electron microscopic (SEM) study. The study disclosed great heterogeneity in the distribution and density of microorganisms on hard as well as soft tissues surrounding the pericoronal pouch. Common features were presence of discrete microenvironments with clusters of bacteria, a decrease in the number of organisms toward the bottom of the pericoronal pouch, and the high proportion of spirochetes, which tended to increase in an apical direction. The study showed leukocytic activity in all areas, and phagocytosis apparently took place on the tissue surfaces within the pericoronal space.

Adult↗

PubMed1981

A scanning electron microscopic study of the two-step effect of cytochalasin B on Ehrlich ascites tumor cells.

The effect of cytochalasin B (CB) on the surface structure of Ehrlich ascites tumor cells was investigated using the scanning electron microscope. The effect occurs in two steps: formation of zeiotic knobs on the cell surface and subsequent grouping of the knobs at one pole of the cell. The early step of zeiotic knob formation occurs at low concentrations of CB (0.5-1 microgram/ml) at 37 degrees C and at high concentrations of the drug (5-10 microgram/ml) at low temperature but within 1 min at 37 degrees C. This step is only partially inhibited by 5 x 10(-3) M sodium azide. The subsequent grouping of zeiotic knobs lasts for more than 2 min at 37 degrees C and occurs only in the case of high concentrations of CB. It is inhibited by sodium azide and is often associated with grouping of the microvilli, which are then lost from all of the cell surface except the area of knob-grouping.

Animals↗

PubMed1983

[Scanning electron microscopic study of hyalin joint cartilage].

Guinea pigs (pirbright white) were subjected to fixed mechanical stress in an endless-belt experiment. Shoulder, elbow, hip, and knee joints were taken and the articular cartilage was prepared for examination with the scanning electron microscope. Ultrastructural findings of cartilage surfaces were described, using different techniques for preparation and fixation. Mechanically stressed animals showed defects in their superficial 'chondrosynovial membrane' with visible fibre networks.

Animals↗

PubMed1985

A morphological comparison of aortic elastin from five species as seen with the scanning electron microscope.

The elastic laminae were extracted from thoracic aortas of adult animals including sheep, dogs, rabbits, cats and rats by treating them in hot alkaline solution (0.1 N NaOH at 75 degrees C) and observed with a scanning electron microscope. The elastic laminae are comprised of sheet-like internal elastic lamina, fibrous and membraneous elastin in tunica media, interlamellar fibers and hollow spaces which we presume were formerly filled with smooth muscle cells in the tunica media. These structures are the same in all five species except that the number of layers and the total thickness of the wall differs.

Animals↗

PubMed1975

Transmission and scanning electron microscope studies of calcified cartilage resorption.

The authors' previous report (Savostin-Asling and Asling, '73) demonstrated that Meckel's carilage is a favorable site for study of calcified cartilage resorption. In the present study the ultrastructural features at this resorption front have been examined by transmission and scanning electron microscopes (19-day rat retus). Multinucleated giant cells chondroclasts) dominated the erosion front. The many features which they showed in common with osteoclasts included abundant mitochondria, vacuolation, lysonsomes, sparsity of rough-sufaced endoplasmic reticulum, and deep infoldings at loci of contact with calcified matrix. Crumbling of matrix (with mineral crystals penetrating between these foldings) and fragmentation of collagen fibrils were also seen. The propensity of chondroclasts for spanning several opened lacunae provided special opportunity to demonstrate cell surface modifications in presence or absence of matrix contact. Amebiod processes extending into lacunae were seen by both transmission and scanning procedures; they were sometimes tipped with a veil of filamentous processes as small as 0.3 mum in diameter. Most hypertrophic chondrocytes. when released from lacunae, appeared to be disintegrating. However, in accord with previous evidence of their possible merger with chondroclasts (in light microscopic studies) there was also evidence for breakdown of cell walls between a chondroclast and a chondrocyte in intimate contact, with possibility of cytoplasmic continuity.

Animals↗

PubMed1978

Thrombus formation in a staged capillary membrane oxygenator associated with a microaggregate blood filter: a scanning electron microscope study.

Blood contact at interfaces in extracorporeal devices is a source of traumas. Proteins are very rapidly adsorbed; then, depending on which proteins are left various degrees of platelet aggregation follow and thrombi develop. The scanning electron microscope reveals very instructive information on the morphology of the blood deposits which adhere to foreign surfaces. Oxygenators such as the Awad D, which is a staged one made of silicone rubber, become "thrombus invaded" after prolonged extracorporeal circulation in spite of adequate heparinization of the blood. In most cases, evaluation of membranes and devices is assessed with respect to transfer of blood gases. Careful examination of the morphology of deposits should be developed. This study shows the importance of blood flow rate, design, and materials.

Animals↗

PubMed2003

Attachment of human periodontal ligament fibroblasts to 3 different root-end filling materials: Scanning electron microscope observation.

OBJECTIVE: The attachment behavior of the human periodontal ligament (PDL) fibroblasts to root-end filling materials (amalgam and Super-EBA) was compared in vitro to gutta-percha by means of scanning electron microscope. STUDY DESIGN: Amalgam and Super-EBA were placed in a prepared cavity of root slices of freshly extracted human teeth and evaluated freshly prepared. Root slices of teeth with cold-burnished gutta-percha filling with AH26 sealer were used for comparison. The root slices were placed in tissue culture cluster, and 1 mL of cell suspension was added carefully over the root slice. They were incubated at 37 degrees C and 100% humidity for 4, 24, and 72 hours. RESULTS: Results showed that the cold-burnished gutta-percha provides a better substrate than amalgam and Super-EBA for cell growth and attachment. Amalgam was the most toxic material, showing early manifestation of cell injury. CONCLUSION: It was concluded that the composition and surface texture of the substrate have an influence on the morphology and the attachment of the PDL fibroblasts. It is suggested that cell attachment and morphology might reflect the biocompatibility of the substratum.

Adult↗

PubMed2000

The vascular supply of the villiform processes in the pharynx of the soft-shelled turtle, Trionyx sinensis japonicus. A scanning electron microscopic study of corrosion casts.

Following our observations of the fine structure of the pharyngeal villiform processes of the hibernating soft-shelled turtle, Trionyx sinensis japonicus (Yokosuka et al., 2000), this paper deals with a scanning electron microscope study of the resin casts of blood vessels supplying those processes. Each villiform process contained arterioles and venules which ran in the axial portion of the process; capillaries formed a network at the periphery of the connective tissue core of the villus. In the distal portions of the villus, the capillaries increased markedly in their caliber to form sinusoidal capillaries. Such a vascular architecture supports the view that the villiform processes serve in the aquatic respiration of the soft-shelled turtle. The casts indicated an occurrence of sphincters in the vascular bed of the villi.

Animals↗

PubMed1993

Scanning electron microscope (SEM) evaluation of clinical failures of single crystal ceramic brackets.

The objective of this work was to perform failure analysis on Starfire brackets that failed in clinical use. The failed brackets were examined with a scanning electron microscope (SEM) to obtain micrographs at magnifications of 20, 50, 100, and other magnifications, whenever necessary. With the aid of the micrographs, the fracture origin and the probable defect that initiated the fracture were identified. The percentages of failure origins for each area of the bracket were arch wire slot 36.0%, tie wing slot 22.0%, undetermined 11.0%, saddle 9.0%, impact 9.0%, during removal 7.5%, and parting area 5.5%. By observing the micrographs pertaining to each field failure, the primary causes of failure were internal defects 47.5%, machining interference 42.5%, and undetermined 10.0%.

Aluminum Oxide↗

PubMed1999

Scanning electron microscopic observation of apical sites of open-type paraneurons in the stomach, intestine and urethra.

The apical region of open-type paraneurons in tubular organs functions as a receptor site for chemical information in the lumen. Electron microscopic studies have demonstrated a tuft of microvilli on the luminal surface of cells, but failed to visualize it three-dimensionally. The present scanning electron microscope (SEM) observation succeeded in viewing, from the luminal side, open-type paraneurons distributed in epithelia of the stomach, intestine, and urethra. The pyloric antrum of avian species and the duodenum of human fetuses, the latter forming an endocrine cell colony at every villus tip, were chosen for SEM observation in order to eliminate visual obstruction by adjacent epithelial cells with developed microvilli. The luminal surface of gut endocrine cells was consistently covered with a tuft of 80-200 microvilli. Pyloric paraneurons possessed thick and stiff microvilli as compared with those of exocrine cells. The microvilli on intestinal paraneurons were more irregular in length and more loosely grouped than those composing the striated border of enterocytes. Urethral paraneurons containing serotonin were surrounded by three or four polygonal epithelial cells. Their narrow apical surface was provided with 30-100 microvilli which varied in length from cell to cell, and which were conspicuously projected above the luminal surface of the urethra. The microvillous crown of the gut and urethral paraneurons was so prominent and constant a structure on the apical surface as to allow easy identification of open-type paraneurons under the SEM.

Animals↗