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At least 811 records · Page 45Linked to original sources
PubMed1994

Study on gutta-percha points using scanning electron microscopy and analysis with electron microprobe.

A comparative study of the apical morphology and contour was performed with the scanning electron microscope at 45x, 70x and 300x, while the chemical composition of eight gutta-percha point brands was surveyed with an EDAX 9100 electron microprobe. They were classified according to their apical morphology as conical (25%) and truncate (75%), based on their contour as regular (50%) and irregular (50%) and according to their surface as without defects (50%) and with defects (50%). The analysis of inorganic compounds revealed the presence of varying proportions of Zn, Ba, Si, Mg. Ca, P, Cl and Al, possibly implying that the presence of Ba and Al could interfere with postendodontic repair or at least irritate the periapical area if inadvertently overfilled.

Electron Probe Microanalysis↗
PubMed1990

Correlative light microscopy, scanning electron microscopy, and transmission electron microscopy of osmium-macerated biological tissues.

A method facilitating correlation of light microscopic (LM), scanning electron microscopic (SEM) and transmission electron microscopic (TEM) images was developed. Rat kidney and heart were initially subjected to the osmium maceration procedure and then embedded in acrylic resin. Semithin sections of the tissue blocks were first provided for LM and then examined by SEM after resin removal. Furthermore, the ultrathin sections adjacent to the semithin sections were observed by TEM. The three-dimensional images of intracellular organelles provided an informative adjunct to LM and TEM.

Animals↗
PubMed1990

Scanning and transmission electron microscopy, and electron probe analysis of the interface between implants and host bone. Osseo-coalescence versus osseo-integration.

Bioinert materials (e.g., alumina implants) and bioactive ceramics (e.g., calcium phosphate ceramics, glass-ceramics) are now extensively used in dentistry. However, the physico-chemical interactions at the interfaces between the implant and the host bone are poorly understood. The purpose of this study was to define the interactions at these interfaces using a combination of analytical techniques: light microscopy, scanning and transmission electron microscopy, electron probe microanalysis, X-ray microradiography, X-ray diffraction, and infrared spectroscopy. Bioinert (pure titanium) and bioactive materials (hydroxyapatite, beta-tricalcium phosphate and biphasic calcium phosphate) were implanted in dogs, and the implants, recovered after various periods of implantation, were analyzed. The results demonstrated the following: the bioactive materials interact with the biological fluid and the living tissues in a specific manner. This process includes biodissolution/biodegradation, apatite crystal precipitation, and bone formation on the implant surface at the expense of the material. The results are discussed according to the limitations of the analytical techniques used. The medical and chemical word coalescence is suggested to describe the specific interactions of bioactive materials and interaction for the phenomenon of physical contact of the bioinert materials with the host bone.

Animals↗
PubMed1987

Tumor vasculature in young and old hosts: scanning electron microscopy of microcorrosion casts with microangiography, light microscopy and transmission electron microscopy.

Tumor growth in vivo is dependent upon new blood vessel formation. When B16-F10 melanoma cells are implanted subcutaneously in young (3 mo) and old (24 mo) C57BL/6 mice the rate of growth is dependent on the age of the mice. This study involved a wide range of histological and microscopic techniques but was limited primarily to the initial phase of tumor growth. Stereological point counting from light microscopy (LM) of standard histological sections has been used to yield data regarding blood content. Tumor-bearing mice were perfused through the aorta with a fixation solution and were infused with a low-viscosity radiopaque gel (Microfil) or resin (Mercox). Soft x-rays of the whole animal were used for identifying the feeding vessels to the tumor. Tumors with Microfil were sliced and used for microangiography and light-microscopic observation while those with resin were used to make corrosion casts for scanning electron microscopy (SEM). The different characteristics of the tumor blood vessels in different aged mice were most obvious through SEM of vascular corrosion casts. In comparison with tumors in young mice those of similar size in old hosts had more necrosis, reduced presence of angiogenic features, decreased vessel density, reduced penetration into the tumor, and enhanced tortuosity of the vessel lumen. Transmission electron microscopy (TEM) revealed incompletely developed wall structure of the vessels regardless of host. The above results are consistent with the hypothesis that retarded angiogenesis may be responsible in part for the limited growth of tumors in old hosts.

Animals↗
PubMed1985

The ultrastructure of the electric burn in man: a transmission electron microscopy-scanning electron microscopy study.

The authors describe the ultrastructural aspects of the electric burn observed with the transmission electron microscope (TEM) and the scanning electron microscope (SEM). With the TEM the most apparent feature is the homogenization and arrangement of the filamentous cytoplasmic material in elongated and parallel bundles together with elongation of the nuclei and junctional structures. SEM studies present a three-dimensional vision of the filamentous material that confirms and clarifies the cellular deformation as a whole. An hypothesis is advanced suggesting that the phenomenon is due to the effects produced by the extremely rapid dehydration of the tissue or that the electric current and Joule effect can act upon the filaments and contractile proteins, causing the cell deformation.

Burns, Electric↗
PubMed1988

Scanning electron microscopy and electron probe microanalyses of the crystalline components of human and animal dental calculi.

A review of the use of scanning electron microscopy (SEM) and electron probe microanalyses in the study of dental calculus showed that such studies provided confirmatory and supplementary data on the morphological features of human dental calculi but gave only limited information on the identity of the crystalline or inorganic components. This study aimed to explore the potential of combined SEM and microanalyses in the identification of the crystalline components of the human and animal dental calculi. Human and animal calculi were analyzed. Identification of the crystalline components were made based on the combined information of the morphology (SEM) and Ca/P molar ratios of the crystals with the morphology and Ca/P molar ratio of synthetic calcium phosphates (brushite or DCPD; octacalcium phosphate, OCP; Mg-substituted whitlockite, beta-TCMP; CO3-substituted apatite, (CHA); and calcite. SEM showed similarities in morphological features of human and animal dental calculi but differences in the forms of crystals present. Microanalyses and crystal morphology data suggested the presence of CaCO3 (calcite) and CHA in the animal (cat, dog, tiger) and of OCP, beta-TCMP and CHA in human dental calculi. X-ray diffraction and infrared (IR) absorption analyses confirmed these results. This exploratory study demonstrated that by taking into consideration what is known about the crystalline components of human and animal dental calculi, combined SEM and microanalyses can provide qualitative identification.

Adult↗
PubMed1979

A semithin light microscopic, transmission electron microscopic and scanning electron microscopic study of macrophages in the lateral ventricle of mice from embryonic to adult life.

A developmental study of intraventricular macrophages was carried out from 11 days post-conception up to 90 days post-natum, using semithin sections, transmission electron microscopy and scanning electron microscopy. In semithin sections and in the TEM three main morphological types (and some transitional forms) were identified and are described as circular, irregular and flattened, respectively. In the SEM three corresponding types were identified, a relatively smooth spherical type, a highly ruffled type and a fairly smooth flattened type. A fourth, multi-blebbed type, was occasionally seen in late prenatal and early postnatal mice. It seemed most likely that these cells were mitotic. The likely sequence of development is that the spherical or circular type is the most primitive, although capable of phagocytosis; and that this differentiates into the ruffled or irregular variety, which in turn differentiates into the flattened type, which is by far the most common type found after birth.

Aging↗
PubMed1984

Smooth-surfaced control and transformed C3H/10T-1/2 cells differ in cytology: a study by secondary electron, backscattered electron and image analysis.

7,12 dimethylbenz-a-anthracene (DMBA)-treated C3H/10T-1/2 mouse embryo fibroblasts have been characterized by the occurrence of pleomorphic microvilli (PMV) in contrast to the non-treated smooth-surfaced C3H/10T-1/2 cells. Recent studies by semiquantitative secondary electron image (SEI) have demonstrated a significant correlation between the number of cells with numerous PMV and the development of oncogenic potential. In these studies, so-called type III transformants scored highest in oncogenic potential and occurrence of cells with pleomorphic microvilli, but always contained a small fraction of cells displaying rather smooth surfaces. Quantitation of the size of nuclei and nucleoli and the number of intranucleolar silver granules after nucleolar organizer region (AgNOR) staining and back scattered electron image (BEI) with an automatic image analysis system (IBAS) revealed that these smooth-surfaced type III cells were significantly different (p less than 0.001) from the non-DMBA transformed smooth-surfaced control C3H/10T-1/2 cells. Compared to PMV transformants, the smooth transformants exhibited smaller nucleoli, a lesser nucleoli/nuclei fraction and fewer AgNOR sites, indicating reduced cellular activity. The biological significance of the smooth-surfaced fraction in PMV-covered type III transformants remains unclear.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Scanning electron microscopic and electron microprobe X-ray analysis of cortical bone of fluoride-treated rabbits.

Sodium fluoride was administered to rabbits through the intragastric route at the rate of 10 mg/kg every day for a period of 8 months. Cortical bone from the diphyseal region of the femur was studied morphologically with a scanning electron microscope, and significant structural changes in collagen fiber were observed in the fluoride-treated animals as compared to normal bone. Similar bone samples were assessed physically for their CaK alpha/PK alpha ratio by electron microprobe x-ray analysis, and chemically for their calcium and phosphorus content. The bone from the rabbits to which sodium fluoride had been administered showed a higher Ca/P ratio than that from untreated control animals by both of the methods of assessment. Possible explanations for the increased Ca/P ratio in relation to the observed structural changes are discussed.

Animals↗
PubMed1984

The presence of siderosomes in synovioblasts (B cells) of chronic spontaneous hemarthrosis. Histologic, electron microscopic, and roentgenographic electron microanalysis studies of three cases.

The synovium of three patients with chronic spontaneous hemarthrosis was examined by light and electron microscopy and roentgenographic electron microanalysis. The synovium showed hyperplastic villous processes with proliferation of synovioblasts (B cells) and synovial macrophages (A cells). Erythrophagocytosis was observed in synovial macrophages but not in synovioblasts. Synovioblasts, however, had more numerous siderosomes than did synovial macrophages. Ferritin granules were identified in the cytoplasms of synovial macrophages and synovioblasts as well as in the intercellular space. It was noted that the longer the interval following the hemorrhagic episode, the fewer the siderosomes and erythrophagosomes in synovial macrophages. Therefore, it is likely that synovioblasts take up ferritin and/or inorganic iron released from synovial macrophages in chronic local iron overload.

Adult↗
PubMed1983

Scope of scanning electron microscopy, transmission electron microscopy and freeze fracture technique in diagnostic cytology of effusions.

A review of the literature on the application of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to cytodiagnosis of neoplastic cells in effusion fluid reveals a lack of consensus as to which of the techniques is most beneficial to a cytologist for a satisfactory diagnosis. The purpose of this study is therefore to critically evaluate the relative merits of SEM, TEM and freeze-fracture (FF) techniques in enhancing the diagnostic "sensitivity" of ultrastructural cytology. Two cases of adenocarcinoma, one case of mesothelioma and one case of small cell undifferentiated carcinoma of the lung were studied in detail by SEM, TEM and FF techniques. A comparative analysis of the results demonstrates that SEM is a rapid and useful technique where the microvilli on the tumour cell surface is the most prominent feature especially in adenocarcinomas. The major handicap of SEM becomes evident in cases where the extreme variability of the surface morphology amongst tumour cells makes it difficult to establish a diagnosis with confidence. TEM along with light microscopy (LM) of toluidine blue sections gives us the most comprehensive method for cyto-diagnosis and is particularly useful in cases where LM cytology alone is inconclusive. It has the added advantage of revealing diagnostically significant nuclear and cytoplasmic features which are helpful in differentiating a benign from a malignant cell and in some instances the probable site of the primary neoplasm. FF technique, though not conducive to a routine diagnostic situation, is of benefit in demonstrating the organization of junctional complexes. From preliminary studies it appears that the tight junctions in adenocarcinoma are different from those seen in small cell carcinoma. In mesothelioma, gap junctions are invariably present, but they are not seen prominently in adenocarcinoma or small cell carcinoma. Thus in poorly differentiated tumours where LM and TEM are inconclusive, FF may prove useful. It is concluded that such coordinated studies in the future have the potential to better our understanding of the nature and behaviour of tumour cells in effusion fluid.

Adenocarcinoma↗
PubMed1994

Scanning electron microscopy and electron probe microanalysis studies of human pineal concretions.

The calcareous concretions of human pineal bodies were investigated with scanning electron microscopy and electron probe microanalysis. The initial concretions measuring 5-7 microns in diameter may have started at the calcified pinealocytes. They grew appositionally forming concentric laminations, and then the simple calcospherulites over 20 microns occasionally aggregated with each other. Some of them became numerous spherulite-aggregated concretions. Others individually grew with scallop-shaped concentric laminations at intervals of 0.05-1 microns and became lobated calcospherulites up to 0.5 mm. The concretions over 0.5 mm were formed by their attachments. The major elements were Ca and P, while traces of S, Mg, and Na were detected. In the calcification and crystallization values, the center of the concretions over 50 microns was significantly higher than the periphery, while there were no differences among the centers and also among the peripheries. The Ca and P amounts in the center were 30.8% and 14.2% by weight and the Ca/P molar ratio was 1.68; thereby the sand-grain-shaped crystals may be nearly hydroxyapatite, as reported previously.

Aged↗
PubMed1995

A new scanning electron microscopy approach to the quantification of bone mineral distribution: backscattered electron image grey-levels correlated to calcium K alpha-line intensities.

The introduction of backscattered electron (BSE) imaging in scanning electron microscopy (SEM) has led to new possibilities for the evaluation of mineral distributions in bone on a microscopic level. The different grey-levels seen in the BSE-images can be used as a measure for the local mineral content of bone. In order to calibrate these BSE-grey-levels (BSE-GL) and correlate them to mineral contents, various attempts, using reference samples with known weighted mean atomic number and/or using simulated bone tissues with known hydroxyapatite concentrations, have been made. In contrast, a new approach is presented here based on measurements of the X-ray intensities of the calcium K alpha-line on selected areas of real bone samples; the measured intensities are then related to the corresponding BSE-GL. A linear positive correlation between weight percent (wt%) calcium and BSE-GL was found. When the BSE-mode is standardized using carbon and aluminum as references, the different mineral contents in bone samples can be recorded as BSE-GL, calibrated to wt% of calcium or hydroxyapatite (HA), respectively. The resulting mineral concentration histograms have a dynamic range from 0 to 89 wt% HA and have a binwidth resolution of 0.45 wt% HA. The presented modifications of the BSE method strongly enhance its feasibility in the field of bone research and its application as a special diagnostic tool for bone diseases.

Bone Density↗
PubMed1997

Analytical electron microscopy as a powerful tool in plant cell biology: examples using electron energy loss spectroscopy and X-ray microanalysis.

Energy filtering transmission electron microscopy in combination with energy dispersive X-ray analysis (EDX) and quantumchemical calculations opens new possibilities for elemental and bone analysis at the ultrastructural level. The possibilities and limitations of these methods, applied to botanical samples, are discussed and some examples are given. Ca-oxalate crystals in plant cell vacuoles show a specific C K-edge in the electron energy loss spectrum (EELS), which allows a more reliable identification than light microscopical or cytochemical methods. In some dicots crystalline inclusions can be observed in different cell compartments, which are identified as silicon dioxide or calcium silicate by the fine structure of the Si L2,3-edge. Their formation is discussed on the basis of EEL-spectra and quantumchemical calculations. Examples concerning heavy metal detoxification are given for some tolerant plants. In Minuartia Zn is bound as Zn-silicate in cell walls; Armeria accumulates Cu in leaf idioblasts by chelation with phenolic compounds and Cd is precipitated as CdS/phytochelatin-complexes in tomato.

Calcium Compounds↗
PubMed1994

Transmission electron and high-voltage electron microscopy of osteocyte cellular processes extending to the dental implant surface.

Examination of the morphology of osteocytes within the bone supporting endosteal dental implants was performed using conventional transmission and high-voltage transmission electron microscopy (HVEM). The in vivo dog model used 72 implants inserted into the premolar region of 18 experimental animals. Forty-eight implants in 12 dogs were used as anterior abutments for fixed bridges for periods up to 12 months. The mineralized matrix of the supporting bone was either directly apposed to the implant surface or was separated from the implant by a narrow region of unmineralized matrix. Osteocytes were routinely observed to be closely associated with the bone-implant interface, as well as at a distance from the implant. Osteocytes were found to extend cellular processes directly to the implant surface through canaliculi. The osteocyte processes contained microfilaments. The three-dimensional capabilities of HVEM elucidated the nature of these cell processes at the point of exit from the osteocyte, as the processes extended through the mineralized matrix, and as the processes terminated at the implant interface. This report suggests that avenues of communication may exist between the implant and the osseous cells, providing intriguing hypotheses regarding biomechanical forces and osteogenesis at the implant interface. Furthermore, an electron-dense deposit was observed upon the inner confines of the canalicular wall, upon the outer aspects of the osteocyte lacuna, and upon the outer aspect of the bone interfacing the implant.

Animals↗
PubMed1992

Degradation, amorphization, and recrystallization of ion bombarded Si(111) surfaces studied by in situ reflection electron microscopy and reflection high energy electron diffraction techniques.

In this paper we report the effect of noble gas ions bombardment on the degradation of atomically flat Si(111) surfaces at room and high (400 degrees C-600 degrees C) temperatures. Reflection high energy electron diffraction (RHEED) and reflection electron microscopy (REM) have been used to characterize the topography and structure of the as-implanted and post annealed surface layers. It is shown that the fading of the specularly reflected beam is not directly related to the amorphization of the surface. This experimental study has also evidenced the difficulties one meets to regrow a defect-free material after amorphization by noble gas bombardment. For high temperature for which the amorphization is not possible, the surface loses its stepped structure and turns into a monocrystalline but atomically rough surface. This roughness is a function of substrate temperature.

Argon↗
PubMed1998

Investigation of cholesterol, bilirubin, and protein distribution in human gallstones by color cathodoluminescence scanning electron microscopy and transmission electron microscopy.

The application of color cathodoluminescent scanning electron microscopy (CCL-SEM) for qualitative luminescence analysis of cholesterol, bilirubin, and protein in human gallastones was demonstrated. Images of these deposits (cholesterol, bilirubin, and protein) were formed in real colors (blue-cholesterol, red, orange-bilirubin, yellow, green-protein) in accordance with the cathodoluminescent spectrum for each control material. The other method described for transmission electron microscopy (TEM) of ultrathin sections provides more detailed characterization of the ultrastructure of cholesterol-containing regions and their spatial interrelations with bilirubin-containing regions. Using CCL-SEM combined with TEM permits the receipt of more complete information about the chemical composition and ultrastructure of gallstones and may lead to more effective understanding of the pathogenesis of cholesterol cholelithiasis.

Bilirubin↗
PubMedDate not supplied

Surface roughness of preparations for backscattered electron-scanning electron microscopy: the image differences and their Monte Carlo simulation.

Patterns and levels of mineralisation in the biological hard tissues have been studied using the backscattered electron (BSE) mode in the scanning electron microscope (SEM). To prevent gross topographic detail overwhelming changes in signal from composition, samples are embedded in polymethylmethacrylate (PMMA) and a flat block surface produced by polishing or micromilling. This study was undertaken to establish the degree of residual topography achieved in these finishing processes. A sample of human rib was embedded in PMMA and prepared, as for examination in the SEM, by polishing on graded abrasives and pre- and, finally, ultramilling. After each preparation step, the block face was imaged using a confocal reflection microscope surface mapping facility. The recorded topographies were used in a Monte Carlo simulation to model the surface interface and thus, for each of the sample preparation techniques, to calculate predicted variations in BSE signal. The latter were compared with experimental data derived under standard operating conditions in the SEM. Micromilling produced block faces with typical peak-trough relief of 80 nm, while hand polishing left occasional scratches 1.5 microns deep with a general undulation of 150-250 nm. Monte Carlo simulations of a rough surface of bone using these data predicted that additional contrast levels of 5% could be expected from micromilled surfaces and > 10% for hand polished samples of bone. Thus, micromilling is the best preparation method for bone, since this tissue develops a collagen orientation-related relief on polishing, which may be largely responsible for the (incorrect) supposition that lamellation in bone is related to changes in net degree of mineralisation.

Humans↗