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Results for “scanning electron microscope”

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PubMed1998

[Scanning electron microscope observation and image quantitative analysis of Hippocampi].

The "scale-like projects" on the derma of 3 species of Hippocampi, H. kuda Bleerer, H. trimaculatus Leach and H. japonicus Kaup were observed by scanning electron microscope (SEM). Results showed that some characteristics such us size, shape and type of arrangement of the "scale-like projects" can be considered as the evidence for microanalysis. Image quantitative analysis of the "scale-like project" was carried out on 45 pieces of photograph using area, long diameter, short diameter and shape factor as parameters. No difference among the different parts of the same species was observed, but significant differences were found among the above 3 species.

Animals↗

PubMed1977

Scanning electron microscopic observations on bone.

The maceration technique employed in the preparation of specimens of bone for museum purposes has also been found to be of use in the preparation of fresh specimens for study with the scanning electron microscope. The technique requires less technical supervision, permits a greater underprocessing to overprocessing margin, and allows comparability of recent biopsy material with previously macerated bone specimens with no less detail than that found by other authors using other techniques on biopsy material.

Bone and Bones↗

PubMed1981

Mitosis as discerned in the scanning electron microscope.

Endosperm cells of Haemanthus katherinae Baker were flattened out between coverslips and fixed by perfusion with glutaraldehyde. Suitable preparations, with mitotic figures which lacked or had a minimum of covering cytoplasm were analyzed in the scanning electron microscope. The different stages of mitosis were documented, and the chromosomes and the spindle were easily differentiable. The observations made on prophase nuclei, the intact mitotic apparatus at metaphase and anaphase, and the phragmoplast at telophase agreed well with what is known about plant mitosis and cytokinesis. Scanning electron microscopy, providing a topographical view of structures, is a complementary means for studies on the structure and function of the mitotic apparatus.

Anaphase↗

PubMed1991

Morphological changes of hepatic microcirculation in experimental rat cirrhosis: a scanning electron microscopic study.

Morphological changes of hepatic microcirculation, especially peribiliary plexus, in experimental rat cirrhosis that resulted from the repeated intraperitoneal injections of N-diethylnitrosamine, 100 mg/kg body weight/one shot/week, were examined by scanning electron microscope. Control rats were treated with saline. Whole blood vessels of the rats were perfused by saline and stuffed with methylmethacrylated resin. Multiple nodular changes were seen in the livers after the five injections (5 wk) of N-diethylnitrosamine, and diffuse nodular transformations mimicking human cirrhosis after six injections (6 wk) were also seen. Overall changes in experimental rats were numerous vascular channels mainly composed of venous branches around the parenchymal nodules, increased arterioportal anastomoses and flattening of veins, especially hepatic vein branches. Peribiliary plexuses of the experimental rats were much richer in the vessels than those of the controls, and many dilated veins, ramified from portal vein branches, were present in the former. Direct connections between peribiliary plexuses and sinusoids or between peribiliary plexuses and portal veins increased in the experimental rats. Studies concerning microcirculatory changes of peribiliary plexuses in experimental rat cirrhosis are rare. It was concluded that the abnormal peribiliary plexuses in this experimental series might participate in a collateral circulation under a state of portal hypertension.

Animals↗

PubMed1982

A scanning electron microscope study of the development of a peripheral sensory neurite network.

The formation of the sensory neurite plexus on the basal lamina of trunk skin in Xenopus embryos has been examined using the scanning electron microscope. It is formed by Rohon-Beard and extramedullary neurons which provide the first sensory innervation of the skin. By observing the distribution of growth cones on the inside surface of the skin of embryos at different ages, the development of the plexus has been followed and related to the development of sensitivity to sensory stimulation. The general features of the plexus are illustrated using a photomontage taken at x 1100. Measurements on neurites from this, and of growth cone orientations demonstrate a general ventral growth pattern with some small regional variations. Interactions of neurites within the plexus are examined. Neurites meeting at shallow angles tend to fasciculate, while those meeting at close to 90 degrees tend to cross each other. Angles of incidence and separation of neurites show few angles less than 30 degrees, which suggests that active adjustments occur after a growth cone meets or leaves another neurite. The observations allow comparison of behaviour of growing neurites in vivo and in vitro. Our evidence suggests that adhesion between growth cones and neurites is stronger than that between growth cones and the basal lamina of the skin.

Animals↗

PubMed1977

Scanning electron microscopic observation of spermiophage cell within the lumen of the epididymal duct of the vasectomized Japanese monkey (Macacus fuscatus).

The spermiophagic process by intraluminal macrophages in the epididymal ducts of the vasectomized Japanese monkey was well visualized with scanning electron microscope. The fragments of disintegrated spermatozoa were seen in the phase enveloped in bulk by flap-like cytoplasmic extensions or in the phase ingested within the cytoplasm.

Animals↗

PubMed1989

Morphological changes in human spermatozoa as examined under scanning electron microscope after in vitro exposure to saponins isolated from Sapindus mukorossi.

Saponins isolated from Sapindus mukorossi have potent spermicidal activity. Morphological changes in human ejaculated spermatozoa after exposure to these saponins were evaluated under Scanning Electron Microscope. The minimum effective concentration (0.05% in spot test) did not affect the surface topography after exposure for 1 minute. However, incubation of spermatozoa for 10 minutes resulted in extensive vesiculation and disruption of plasma membrane in the head region. Higher concentrations (0.1%, 1.25%, 2.5% and 5.0%) caused more or less similar changes which included vesiculation, vacuolation, disruption or erosion of membranes in the head region. These findings suggest that the morphological changes observed are due to alterations in the glycoproteins associated with the lipid bilayer of plasma membrane of spermatozoa.

Humans↗

PubMed1998

Scanning electron microscope appearances of Lightspeed instruments used clinically: a pilot study.

The cutting heads of the first 18 instruments in six sets of clinically used Lightspeed instruments (sizes 20-65) were examined in a scanning electron microscope (SEM). Three sets had been used by full-time faculty and discarded as follows: instrument sizes 20-32.5 after 18 treated root canals; instrument sizes 35-47.5 after 36 treated root canals; and instrument sizes 50-65 after 54 treated root canals. Three other sets had been used by a private clinician who discarded all Lightspeed instruments after preparing 20 root canals. The cutting heads of the 108 instruments were examined for the presence of surface debris, metal strips, metal flash, disrupted cutting edges, microfractures, tears, pitting and fretting and fatigue cracks. Fewer instruments ultrasonically cleaned before examination in the SEM had debris than those not cleaned before examination. The prevalence of metal strips and metal flash was similar for both groups. In contrast, microfractures and tears were more prevalent in instruments used by the full-time faculty group, who used their instruments more frequently before discarding them. Pitting and fretting occurred equally frequently in both groups whilst no fatigue cracks were noted in any of the 108 instruments. Overusage of Lightspeed instruments may predispose the flutes of the cutting heads to microfractures and clinicians should be aware of this possibility.

Alloys↗

PubMed1976

Scanning electron microscopic observations of the common carotid artery of the rat. III. Heparin effect on platelets.

After administration of high systemic doses of heparin verified by assay, common carotid arteries in the rat were divided and sutured. Scanning electron microscope observations of endothelial surfaces showed a decrease in platelet adhesion, as well as a reduction in the adherence of other circulatory blood elements when compared to controls. This is the first report indicating the in vivo effect of high dose systemic heparin on platelets.

Animals↗

PubMed1983

Scanning electron microscopic observation of the parasitic forms of Fonsecaea pedrosoi in a human skin lesion.

The parasitic form of Fonsecaea pedrosoi in the superficial hyperkeratotic layer of the skin, in a patient with chromoblastomycosis, was observed by a scanning electron microscope using some technical improvements. The fungus elements were comprised of branched septate hyphae with spherical cells and sclerotic cells. It was observed that the sclerotic cells, divided into two or three parts, formed a germ tube.

Aged↗

PubMed1984

Scanning electron microscope specimen preparation technique for dissociated strial marginal cells.

Single strial marginal cells from the cochleas of guinea pigs and chinchillas were successfully isolated in tissue culture medium using the enzyme dissociation technique. Such single cells were successfully preserved for scanning electron microscopic observation in special glass wells following the freeze drying technique. Judging by transmission electron microscopic examination of such cells, the ultrastructural preservation of the dissociated strial marginal cells was excellent.

Animals↗

PubMed1980

Scanning electron microscopic studies of the surface morphology of the vomeronasal epithelium and olfactory epithelium of garter snakes.

Fixed vomeronasal and olfactory epithelia from normal adult garter snakes were microdissected, fractured, and examined with a scanning electron microscope. The method permits a detailed comparative study of the structural organization and morphological characteristics of the constituent cells of the vomeronasal and olfactory epithelia. Despite similarities in the nomenclature of the constituent cells in both epithelia, significant differences exist in their surface morphology. A unique columnar structure composed of non-neuronal elements is present in the vomeronasal epithelium. These columns house the bioplar neurons and undifferentiated cells. Such a columnar organization is absent in the olfactory epithelium. In vomeronasal epithelium the bipolar neurons possess microvillous terminals at their dendritic tips, while the dendritic tips of the bipolar neurons of the olfactory epithelium possess cilia. Vomeronasal supporting cells are covered with microvilli, while olfactory supporting cells are covered with cytoplasmic protuberances in addition to the microvilli. In the vomeronasal epithelium the pear-shaped neurons have a grossly smooth surface and are organized into clusters, while in the olfactory epithelium the elliptical bipolar neurons are spinous, aligned side-by-side and interdigitate. The basal (undifferentiated) cell layer in the vomeronasal epithelium has a high packing density and is composed of several layers of irregularly shaped cells. In the olfactory epithelium the basal cell layer is loosely organized and composed of a single layer of oval cells. This information on the three-dimensional cell structure of both epithelia provides a basis for experimental observations on changes in morphology of the bipolar neurons during genesis, development, maturation, degeneration, and regeneration in postnatal, adult animals.

Animals↗

PubMedDate not supplied

Scanning electron microscopic study of the organ of Corti in normal and sound-damaged guinea pigs.

A method was evolved by which the organ of Corti could be examined in its entirety with the scanning electron microscope, the organ meanwhile retaining its spiral form. This made it possible to assess traumatic effects on the cochlea and qualify lesions in terms of extent, localization and pattern. It was also found possible eventually to cut the same specimen into sections for cellular and subcellular studies. The number of guinea pigs examined totalled 91, divided into three groups. The first group was used to study the anatomy of the organ of Corti with special reference to normal variations and artifacts. Unmistakable indications were found that the longest stereocilia of the inner hair cells are linked to the tectorial membrane. The animals of the second group were exposed to pure tones of high intensity, whereupon, lesions of the organ of Corti were described according to intensity, time, and frequency. Three different types of otologic drills were used to perform mastoidectomies on temporal bones and on the cadaver. The noise produced was analyzed as to intensity and frequency range. It was found that the drill with the lowest rpm (and highest torque) produced the highest noise intensities, at levels which can be traumatic to the human organ of hearing. The animals of the third group were exposed to the amplified noise produced by otologic drills of three different types. The resulting lesions in the organ of Corti were examined by the method described for scanning electron microscopy and compared. In spite of the wide variation in individual lesions, patterns of degeneration of three different types could be distinguished. The high-speed and the very-high-speed drill inflicted less damage on the organ of Corti than the low-speed drill. It is therefore advised to refrain from using the latter drill in prolonged operations.

Animals↗

PubMedDate not supplied

Scanning electron microscopic study on the shape of infertile seminiferous tubules: a hypothesis of pathogenesis of idiopathic male infertility.

The shape of infertile seminiferous tubules was studied on testicular biopsied specimens from patients with idiopathic male infertility using the scanning electron microscope. A parallel study of the same sections was performed by ordinary light microscopy. Normal seminiferous tubules were revealed to be shaped like a weaving cylinder, whereas infertile seminiferous tubules were strangulated in various places, or appeared similar to a tail-like rope which became gradually more slender. These strangulated or slender parts of tubules seemed to correspond to the smaller tubules with thickened tubular walls that were recognized under the light microscope. It is suggested that these thickened tubular walls suppress spermatogenesis by a nutritional disturbance, and the strangulations of infertile tubules interfere with sperm transport by tubular blockage or germinal disorganization and interrupted contractions of the tubules.

Adult↗

PubMed1992

[A scanning electron microscope assessment of the changes induced by wear on subsonic endodontic instruments].

The aim of the present work was to study the wear of a special kind of subsonic instruments with usage. We have examined with scanning electron microscope new and used instruments: the first to estimate the features and degree of final touches; the second to examine how they wear after 1, 3 and 5 minutes. We tested for each period 3 instruments per size. In all we controlled 72 instruments. The results of the study show that after 5 minutes the instruments are very worn.

Materials Testing↗

PubMed1981

Excitation under the scanning electron microscope of DNA-associated fluorescence from chicken erythrocyte nuclei, polytene chromosomes and adenovirus 2 virions.

Biological structures not seen by conventional light microscopy, such as longitudinal striations in polytene chromosomes, and, at the limit of sensitivity, virions of adenovirus 2, have been detected via DNA-associated fluorescence excited under the scanning electron microscope. The maximum sensitivity realized, about 1 detected photon per 700 base pairs, falls short by about an order of magnitude of that required to achieve, in unreplicated specimens, the 2 nm intrinsic resolution of the method. A combination of D2O-H2O substitution with freeze-drying provides the best unquenching procedure found for in situ DNA. DNA-associated fluorescence for light microscopy can be created by moderate exposure of the specimen in the electron microscope.

Adenoviruses, Human↗

PubMed1990

A clinical scanning electron microscope study of tooth surface preparation and bonding.

This clinical study utilized cut dentine surfaces on which the Creation Bond System and Scotchbond were applied after various surface treatments. It was observed under the scanning electron microscope that preparation with a tungsten carbide bur left a smear layer on the dentine. When this surface was pumiced, the smear layer remained and the tubules were plugged with smear debris. Polyacrylic acid and citric acid removed the smear layer from the dentine surface. When the Creation Bond System was applied to the surface treated with polyacrylic acid, hollow depressions were produced. Application of the Creation Bond System to the surface treated with citric acid resulted in some resin tag formation into the dentinal tubules as well as hollow depressions on the resin surface. The presence of these irregularities in the resin indicated fluid from the dentinal tubules prevented contact of the bonding resin with the dentine surface. This degree of contamination was not observed when Scotchbond was applied to a pumiced dentine surface.

Acid Etching, Dental↗

PubMed1999

Signal components in the environmental scanning electron microscope.

We demonstrate that the gas-amplified secondary electron signal obtained in the environmental scanning electron microscope has both desired and spurious components. In order to isolate the contributions of backscattered and secondary electrons, two sets of samples were examined. One sample consisted of a pair of materials having similar secondary emission coefficients but different backscatter coefficients, while the other sample had a pair with similar backscatter but different secondary emission coefficients. Our results show how the contribution of the two electron signals varies according to the pressure of the amplifying gas. Backscatter contributions, as well as background due to gas ionization from the primary beam, become significant at higher pressure. Furthermore, we demonstrate that the relative amplification efficiencies of various electron signals are dependent upon the chemistry of the gas.

Journal Article↗