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PubMed1997

Application of the low vacuum scanning electron microscope to the study of biomaterials and mammalian cells.

The use of the scanning electron microscope (SEM) in 'low' (reduced) vacuum (lvac) mode permits observation of specimens which have not been coated with a conductive material such as gold or carbon. We have evaluated the use of this mode of observation to the study of biomaterials using the bone-substitute material Interpore as an example. On this material, rat bone cells were visible in lvac mode only in cells traversing pores, when they were readily identified by their cell nuclei. Rat calvarial bone examined uncoated in lvac mode showed the bone structure clearly through the overlying layer of osteoblast cells, which were subsequently revealed by gold coating. Immunogold labelling of alkaline phosphatase was imaged in lvac mode, following silver enhancement and carbon coating. These studies demonstrate the complementary use of the lvac and high vacuum (hvac) SEM to study material composition, the behaviour of mammalian cells on biomaterials and the potential use of lvac SEM to study mineralized tissues without removal of overlying soft tissue.

Alkaline Phosphatase↗
PubMed1990

Field emission scanning electron microscopic study on the noninfarcted myocardium after myocardial infarction.

Intracellular membranous ultrastructural changes in the noninfarcted myocardium of the left ventricle were studied by examining experimental myocardial infarction in rats with a field emission scanning electron microscope. The left coronary artery was ligated at its origin for 7 days. The resulting infarcts comprised approximately 40% of the total area of the left ventricles. In a light microscopic study, the transverse diameter of myocytes had increased to 17.1 +/- 2.9 microns in the noninfarcted myocardium, compared to 14.1 +/- 3.1 microns in the myocardium of sham-operated rats (p less than 0.01). For the scanning electron microscopic study, the specimens were processed according to the Osmium-DMSO-Osmium method. Marked morphological changes of intracellular membranous structures were found in the noninfarcted myocardium, especially in the lacelike network of sarcoplasmic reticulum which occasionally formed large flattened cisternae, and in the marked proliferation of surface caveolae. It is speculated that these early ultrastructural changes in the noninfarcted myocardium reflect an adaptation of microorganellae in the failing hearts of the rats.

Animals↗
PubMed1977

Correlation of scanning electron microscope and light microscope findings in uninflamed and pathologically involved human pulps.

The use of the scanning electron microscope has been investigated as a modality for pulpal diagnosis. Findings in ten normal, inflamed, and necrotic human pulps were correlated with light microscope findings. Inflammatory cell identification by SEM was found to be difficult. The inflammatory cells, especially lymphocytes, appeared in varying forms in SEM. Polymorphonuclear leukocytes and macrophages had similar surface structure. Degenerative changes of cells and fibers and dystrophic mineralizations were graphically depicted by SEM.

Abscess↗
PubMed1981

Rapid maxillary expansion and external root resorption in man: a scanning electron microscope study.

The effects of rapid maxillary expansion on the external root structure of thirteen appliance-attached and five unattached maxillary first premolars from nine patients have been investigated with the scanning electron microscope (SEM). Topographic features of cementum and dentine resorption, as well as initial and subsequent remineralization changes, are described in detail. All anchor premolars exhibited root resorption, which was mostly confined to the buccal surface. Generally, the longer an anchor tooth remained in fixed retention, the more extensive the buccal root resorption. In contrast, the unattached maxillary first premolars and the opposing mandibular first premolars showed no evidence of resorption. Active resorption was the dominant process in anchor premolars extracted almost immediately after rapid expansion. Subsequently, repair became the predominant process, but continuing resorption was apparent even after 9 months of retention. Repair of root defects occurred by the deposition of cellular cementum which revealed little evidence of principal periodontal fiber reattachment within the advancing mineral front. The resorption pattern identified in the scanning electron microscope was not detected by in vivo radiographic examination. The significance of the findings is discussed.

Activator Appliances↗
PubMedDate not supplied

Application of the low-loss scanning electron microscope image to integrated circuit technology. Part 1--Applications to accurate dimension measurements.

Scanning electron microscopes (SEMs) are the most extensively used tools for dimensional metrology and defect inspection for integrated circuit technologies with 180 nm and smaller features. Currently, almost all SEMs are designed to collect as many secondary and backscattered electrons as possible. These signals are mainly secondary electrons (SE1, SE2, and SE3) detected with various detection schemes. To facilitate the electron collection, very strong electric and magnetic fields are applied not just in the path of the primary electron beam but to the emerging electrons as well. These new systems provide strong signals, thus better signal-to-noise ratio, and thus resulting in higher throughput than older ones. On the other hand, the use of secondary electrons means that measurement results are much more prone to the detrimental effects of electron beam interactions, sample charging, and sample contamination than measurements with higher-energy backscattered electrons. The use of backscattered electrons, especially low-loss electrons (LLE), can provide better surface sensitivity, edge accuracy, and repeatability, possibly at the expense of measurement speed. This two-part study investigates the benefits and drawbacks of low-loss electron imaging to edge characterization for dimensional metrology and enhancement of fine surface features done through filtration or separation of the generated LLE signal and the use of energy-dependent signals. Part 1 reviews and illustrates the potential for accurate dimensional measurements at low accelerating voltage by LLE, and Part 2 will concentrate on the enhancement of surface features in chemical-mechanically planarized specimens with the use of a novel LLE detector.

Journal Article↗
PubMed1986

Differential diagnosis of Crohn's disease of the colon from ulcerative colitis: ultrastructure study with the scanning electron microscope.

Mucosal biopsies from patients with Crohn's disease and with ulcerative colitis were studied by scanning electron microscopy. Important abnormalities of the mucosal surface were found in both diseases. For Crohn's disease, the characteristic abnormality was loss of the regularity of the polygonal units, but with preservation of the mucosal integrity and of the normal mucosal design. For ulcerative colitis, the abnormalities were disorganization of the cells, signs of sloughing, and superficial erosions. Patients with Crohn's disease always had a significantly increased number of muciparous cells, while those with ulcerative colitis had obvious signs of decreased mucus production. The lesions of ulcerative colitis could be seen under the scanning electron microscope in mucosal areas that appeared normal endoscopically. We feel therefore that scanning electron microscopy of biopsy specimens from patients with inflammatory bowel diseases can be of great help in differential diagnosis.

Colitis, Ulcerative↗
PubMed1988

Studies on the chromosome by scanning electron microscope--a new trial with long-term Giemsa staining.

Chromosomes, which can be seen under a light microscope (LM) as bands, are too thin to see with a scanning electron microscope (SEM). We noticed that chromosomes increase in thickness with Giemsa staining, so that scanning microscopic specimens could be prepared by long-time Giemsa staining for SEM observation, and in the present study the following results were obtained. 1) When the duration of the trypsin treatment was kept constant, and the Giemsa staining was performed from 30-min to 24-h, it was found that the thickness of the chromosomes increased with the length of treatment time, and the fibrous structures were clearly seen. 2) While a sufficient thickness of the chromosomes was obtained with the long-time Giemsa staining, the bands became unclear as the time of staining was extended. 3) A long-time Giemsa staining without trypsin treatment showed more "highly packed" fibers, so that the trypsin treatment was felt to be related to the dispersion of the fibers.

Azure Stains↗
PubMedDate not supplied

Scanning electron microscopic appearance of rat otocyst of the twelfth postcoital day: elaboration of a method.

A method for removal, fixation, microdissection, and drying of early rat otocyst for examination by the scanning electron microscope is elaborated. Tissues were dissected, fixed as for conventional transmission electron microscopy and dried by critical point evaporation using amylacetate as the transitional fluid and carbon dioxide as the pressure head. Otocysts were either dissected at the time of initial fixation, or subsequent to drying. The otocyst of the 12th postcoital day was used as a model system in this preliminary report. Critical point drying retained the overall configuration and the fine ultrastructural detail of the otocyst. The interior otocystic surface was visualized and cilia bearing cells of the luminal surface were identified. Most if not all of these cells had a comspicuous, but short kinocillum which terminated in an ovoid bulb. The scanning electron microscopic appearance was correlated to the transmission electron microscopic image seen in the second paper in this Supplement.

Animals↗
PubMed2003

Smear layer production by 3 rotary reamers with different cutting blade designs in straight root canals: a scanning electron microscopic study.

OBJECTIVES: The design of the cutting blade of rotary instruments may affect the outcome of root canal instrumentation in terms of cleanliness. The aim of this scanning electron microscopic study was to compare the quality and amount of smear layer generated in the apical third of straight root canals by 2 rotary nickel-titanium reamers and 1 rotary steel reamer with different cutting blade designs. STUDY DESIGN: Seventy intact, single-rooted human mandibular premolars with straight, fully developed roots were selected for this study. Before instrumentation, the cervical portion of all teeth was removed by using a microtome (Isomet), leaving 13-mm-long roots. Automated preparation was performed with ProFile (n = 20) and Hero 642 (n = 20) reamers by using the crown-down technique and with a stainless steel engine reamer (Mani; n = 20) by using a reaming motion. All root canals were instrumented to No. 40. A control group (pulp extirpation with barbed broaches; n = 10) was also included. Irrigation with 3 mL of a 1% sodium hypochlorite (NaOCl) solution was performed after each instrumentation. After the instrumentation, each root was split longitudinally, and a scanning electron microscope was used to examine the selected areas of the canal walls at the apical third from 2 different perspectives. A 4-category scoring system for smear layer was used, and the resulting scores were statistically analyzed. RESULTS: The least smear layer remained in the Hero 642 group at the selected apical third of straight root canals (P < .05). However, all instruments left a smear layer. The surface texture of the smear layer, in addition to the depth and the frequency of packed materials into the dentinal tubules, varied with instrument type. CONCLUSION: These data revealed that the design of the cutting blade of rotary instruments can affect root canal cleanliness in straight root canals. This information may be useful in the selection of nickel-titanium rotary reamers.

Dental Alloys↗
PubMed1981

Shunting in renal microvasculature of the rat: a scanning electron microscopic study of corrosion casts.

We reinvestigated the still controversial existence of arterial pathways by-passing glomeruli within kidneys of rats from weaning to more than 12 months old (i.e., body weight ranging from 39 g to 643 g). For this purpose, the arterial injection of microspheres 7.5 micrometer to 17 micrometer in diameter was combined to corrosion-replication of the arterial bed of a vasodilated perfused kidney preparation. This procedure allowed easy detection of arterial by-passes with light microscope and detailed observation with scanning electron microscope. Our results clearly demonstrate the existence of various categories of arterial by-passes throughout renal cortex regardless of age. Some of them had never been described before. These vascular by-passes were found with increased frequency from superficial to juxtamedullary cortex. In the latter area, frequency was not age-dependent, and approximately 10% (range 4-22%) of juxtamedullary glomeruli were involved. Data derived from previous microsphere studies would suggest that these structures are (partially) nonfunctioning in basal physiological conditions, but more information is needed to assess their possible functional role in the rat.

Animals↗
PubMed1990

A scanning electron microscope study of the iatrogenic fractures produced by intra-radicular dental techniques.

Iatrogenic fractures are frequently produced by certain dental techniques, such as lateral condensation or the use of intra-radicular screws or pins. In the present study, we have described these fractures by means of the scanning electron microscope. Although several authors have pointed out the difficulty to visualize the iatrogenic fractures, they can be easily showed under the scanning electron microscope.

Humans↗
PubMed2004

Micromorphology of sialoliths in submandibular salivary gland: a scanning electron microscope and X-ray diffraction analysis.

PURPOSE: Sialoliths are common in the submandibular gland and its duct system. The exact cause of formation of a sialolith is still a matter of debate. The aim of this study was to analyze 6 sialoliths ultrastructurally to determine their development mechanism in the submandibular salivary glands. MATERIALS AND METHODS: Six sialoliths retrieved from the hilus and duct of the submandibular salivary glands of 6 patients with sialadenitis were analyzed ultrastructurally by scanning electron microscope and x-ray diffractometer. RESULTS: Scanning electron microscope revealed mainly irregular, partly rudely hexagonal, needle-like and plate-shaped crystals. The cross-section from the surface to the inner part of the sialoliths showed no organic material. X-ray diffraction showed that the sialoliths were composed of hydroxyapatite crystals. Energy dispersive x-ray microanalysis showed that all of the samples contained high levels of Ca and P, and small amounts of Mg, Na, Cl, Si, Fe, and K. CONCLUSION: The main structures of the submandibular sialoliths were found to be hydroxyapatite crystals. No organic cores were observed in the central parts of the sialoliths. In accordance with these preliminary results, sialoliths in the submandibular salivary glands may arise secondary to sialadenitis, but not via a luminal organic nidus.

Calcium↗
PubMed1996

Measuring the performance of scanning electron microscope detectors.

A simple digital method of measuring the performance of detectors in the scanning electron microscope (SEM) is described. The value derived is absolute and can therefore be used to compare both different detectors on the same instrument as well as different detectors on different instruments. The technique can be applied to secondary electron, backscattered electron, and energy-dispersive x-ray detectors. Examples are given of measurements made on a variety of commercial detectors installed on a number of current SEMs.

Microscopy, Electron, Scanning↗
PubMed1980

Scanning electron microscopic observations on glomeruli: its use in thermally injured patients with renal impairment.

Previous scanning electron microscopic (SEM) studies have suggested that morphological changes occur in the glomeruli of animals with experimental acute renal failure (ARF). No SEM studies have been reported on human glomeruli in ARF. Sixteen thermally injured patients were studied by SEM and the observations were correlated with the light microscopic findings and clinical data. The group studied contained patients with normal renal function as well as patients with varying degrees of renal impairment, including ARF. The findings failed to demonstrate specific morphological alterations associated with ARF in the human.

Acute Kidney Injury↗
PubMed1987

Carotid plaque as a source of emboli in humans: a scanning electron microscopic study.

Ten fresh carotid plaques obtained from patients undergoing carotid endarterectomy were fixed, and their luminal surfaces were examined with a scanning electron microscope. Luminal surface defects, characterized in scanning electron microscopy as endothelial discontinuities having diameters of 50 to 1500 microns, were a frequent finding, but their presence did not correlate well with the location of ulcers seen on angiography. Potential sources of emboli found were peels of subendothelial matrix, fibrin-platelet aggregates, fibrin-red blood cell clusters, and, possibly, damaged endothelial cells. Areas of endothelial cell injury consisting of small denuded patches, sheets of endothelial cytoplasm, and distorted endothelial cell profiles were observed. These areas resembled the type of damage seen in experimental ischemic vessel lesions and were believed to be the result of carotid cross clamping. Their presence suggests that a similar mechanism may result in loss of endothelial cells and exposure of the "raw" plaque surface in vivo.

Brain Ischemia↗