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PubMedDate not supplied

Scanning electron microscope charging effect model for chromium/quartz photolithography masks.

We propose a new method for fitting a model of specimen charging to scanning electron microscope (SEM) images. Charging effects cause errors when one attempts to infer the size or shape of a specimen from an image. The goal of our method is to enable image analysis algorithms for measurement, segmentation, and three-dimensional (3-D) reconstruction that would otherwise fail on images containing charging effects. Our model is applied to images of chromium/quartz photolithography masks and may also work in the more general case of isolated metal islands on a flat insulating substrate. Unlike methods based on Monte Carlo simulation, our simulation method does not handle more general topographies or specimens composed entirely of an insulator; it is a crude approximation to the physical charging process described in more detail in Cazaux (1986) and Melchinger and Hofmann (1985), but can be fit with quantitative accuracy to real SEM images. We only consider changes in intensity and do not model charging-induced distortion of image coordinates. Our approach has the advantage over existing methods of enabling fast prediction of charging effects so it may be more practical for image analysis applications.

Journal Article↗
PubMed1979

The migration of lymphocytes across the vascular endothelium in lymph nodes: a scanning electron microscopic study.

Endothelial cells of Postcapillary Venules (PCV) and the passage of lymphocytes through the wall of PCV were investigated with Scanning Electron Microscope (SEM) in mesenteric lymph nodes of rats. Individual endothelial cells of PCV in the lymph node did not have flat surface or were not typically cubic, but swelled at the central part assuming a foot ball-like shape. Circulating lymphocytes are considered to migrate into lymphatic tissues through the wall of PCV from the blood stream. Two hypotheses, inter-endothelial cell passage and intra-endothelial cell passage, have been proposed. The three-dimensional studies on lymphocytes passing the wall with SEM confirmed that migrating lymphocytes pushes their way through the intercellular space with pressing the adjoining endothelial cells from beginning to end, supporting the former hypothesis. Invasion of lymphocytes into endothelial cells were not observed.

Animals↗
PubMed1987

Preparation of retinal vessels for scanning electron microscopic examination using microdissection by ultrasonication.

A method of microdissection by ultrasonication was used to prepare blood vessels of the retina for scanning electron microscopic examination. Eye cups were treated with 2% OsO4 that contained 2% CHAPS or 1% saponin (16 hrs.), dehydrated to 100% acetone, sonicated at 80 kHz (40 min.), and further processed by conventional means. This treatment resulted in the separation of the outer and inner retina at the level of blood vessels in the outer plexiform layer. The overall pattern of the blood vessels was maintained. Venules were distinguished from capillaries. This technique may provide information that is not possible to obtain with corrosion casts or trypsin digests.

Animals↗
PubMed1982

Views of the endothelial surface of the marginal sinus in rat spleens using the scanning electron microscope.

The cell-passing pores and the endothelial surface of the marginal sinus of the rat spleen were studied using a scanning electron microscope. The cell-passing pores were observed to be limited to the endothelial junction of the marginal sinus on the marginal zone side. They were so large that blood cells might easily pass through them. The cell-passing pores were thought to be the main pathway for blood cells moving from the marginal sinus to the marginal zone. The endothelial surface was relatively smooth, although some granular microvilli were distributed irregularly on the surface. At the endothelial junction, microvilli-like projections lined the junctional edge.

Animals↗
PubMedDate not supplied

Scanning electron microscopic study on the distribution of epithelial cells in the Eustachian tube.

Canine Eustachian tube epithelium was examined by means of the scanning electron microscope. The part of the tube at the bone-cartilage junction was found to be the most active. It is here that goblet cells and large numbers of ciliated cells were found. Cilia were dense and covered by a mucus blanket. Near the tympanic end of the Eustachian tube, goblet cells were more numerous and ciliated cells less so. Near the pharyngeal end, goblet cells were numerous, while cilia were scanty and not uniform in length. Our findings support the concept that middle ear clearance is carried out by an active mucociliary mechanism as in other parts of the upper respiratory system.

Animals↗
PubMed1986

Leptomeningeal cysts after spot freezing: transmission and scanning electron microscopic observations.

The sequential development of the early phases of leptomeningeal cyst formation was studied in an experimental model. Light, transmission and scanning electron microscopic data were compared with those from human arachnoid cysts. Common features observed were: the participation of leptomeningeal cells in the structure of the cysts with exclusion of dural components; the absence of internal traversing trabeculae; the hyperplasia of leptomeningeal cells, particularly in the dome of the cysts. Other features of the experimental cysts were: the splitting of the pio-arachnoid membrane; the scarcity of collagen at the early stages; the presence of areas of mineralization at more advanced stages; the presence of remodeling parenchymal changes at the underlying nervous tissue.

Animals↗
PubMed1993

[Scanning electron microscopic observation on the encysted and excysted metacercariae of Paragonimus heterotremus].

The surface ultrastructure of metacercariae of Paragonimus heterotremus was studied by scanning electron microscope. Encysted metacercaria was egg-shaped with a button-like structure on its end. The oral sucker of the newly excysted metacercaria was larger than the ventral sucker. Single-pointed spines were covered densely on all of the tegumental surface. There were two and three rings sensory papillae on the oral and ventral suckers, respectively. Six papillae of the most inner ring were distributed on the ventral sucker inner-pore symmetrically. A few sensory papillae were dispersed on each side of the anterior part of the worms. These papillae of some excysted metacercariae were arranged irregularly in two rows with 5 to 6 papillae in each row (Figs. 1-8).

Animals↗
PubMed2003

Scanning electron microscopic observations of the development of the chicken caecum.

The surface pattern of the caeca of the chicken was examined using the scanning electron microscope (SEM) in stages ranging from 11th day of foetal development to 60 days of post-natal life. During incubation the proximal region (basis) of the caecum presented a few irregular elevations, which were later regarded as villi and after hatching, gradually, became longer and wider. These structures were found to be similar to those of the small intestine. The middle (corpus) and distal (apex) regions of caecum presented ridges/folds with short and blunt villi that were even shorter in the apex. The ridges/folds were running longitudinally the inner surface of the corpus while those of the apex were not so well developed.

Animals↗
PubMed1980

Appearance of chemically treated root canal walls in the scanning electron microscope.

The dissolving effects of seven endodontic solutions on unprepared root canal walls of young intact human premolars were evaluated with the scanning electron microscope. After incubation at 37 degrees C in distilled water or isotonic saline for 10 min the predentinal surfaces showed no changes as compared with untreated controls. The demineralizers Decal and Largal Ultra had little effect on the organic tissues but caused some decalcification where mineralized dentin was exposed. Nelex caused concentration-dependent coagulation of the residual pulp tissue, making typical ring structures on the surfaces. Sodium hypochlorite at 2.5% and 5.0% dissolved most of the predentin, exposing the globular appearance of the mineralizing front. Salvizol produced small globules on otherwise intact surfaces. Dissolution of both the organic and inorganic tissue of the root canal wall would require the combined use of two of the solutions studied.

Acetates↗
PubMed1982

Microcirculation of the rat adrenal gland: a scanning electron microscope study of vascular casts.

Blood vascular beds of the rat adrenal gland were filled with methacrylate resin and observed with a scanning electron microscope. The classical findings on mammalian adrenal glands of Flint (1900), Bennett and Kilham (1940), and Gersh and Grollman (1941) were confirmed. The cortical capillaries arise from the cortical arteries and converge at the corticomedullary junction into the peripheral venous radicles which flow into the tributaries of the central vein. The medullary capillaries originate from the medullary arteries and drain through the deep venous radicles into the tributaries of the central vein. No direct connection between the cortical and medullary capillaries was noted except for rare communications via the peripheral venous radicles. These findings show that most of the cortical blood, rich in glucocorticoids, flows in the medulla, not through the medullary capillary plexus but exclusively through the radicles of the central vein. Evidence for adrenal portal vessels could not be found.

Adrenal Cortex↗
PubMed2002

Changes in dentin after insertion of self-threading titanium pins with 3 methods: a scanning electron microscope pilot study.

STATEMENT OF PROBLEM: Inserting a self-threading pin can cause dentinal cracks, but it is not known whether dentin bonding agents can penetrate these cracks. PURPOSE: Part I of this in vitro pilot study was conducted to document the presence of dentinal cracks after the placement of self-threading pins with 3 methods. Part II was conducted to observe changes in dentin when a dentin bonding agent was applied before insertion of the self-threading pins. MATERIAL AND METHODS: The crowns of 14 noncarious third molars were sectioned horizontally 2 mm above the cemento-enamel junction, and the occlusal portions were discarded. The teeth were put into a nontransparent bag and divided randomly into 2 groups. Group 1 consisted of 12 teeth. In each tooth, 4 pinholes were prepared with a handpiece at normal rotation speed (30,000 rpm). Self-threading pins were placed into 3 of the pinholes in each tooth: 1 manually, 1 by handpiece at 7000 rpm, and 1 by handpiece at 30,000 rpm. The fourth pinhole was left empty and served as the control. All group 1 teeth were sectioned vertically through the pins, dental hard tissue, and control pin holes. The examination surface of each specimen in group 1 was polished, and the smear layer was removed with Calcinase and NaOCl solutions. After dehydration in ascending grades of alcohol, specimens were coated with a 10- to 15-nm-thick layer of gold and examined with a scanning electron microscope. In the remaining 2 teeth (group 2), a dentin bonding agent was introduced into the pinholes prior to pin placement. Two pins were placed manually and 2 by handpiece at 30,000 rpm. After pin placement, sectioning, cleaning, and dehydration, the specimens were examined with a scanning electron microscope, and x-ray mapping was performed to determine the presence of titanium, silicon, and calcium. RESULTS: Craze lines in dentin were associated with 54.5% of pins placed manually and 54.5% of pins placed with a handpiece at reduced speed (7000 rpm). Dentinal cracks were associated with 50% of pins placed with a handpiece at standard speed and with 16.7% of the control pinholes. X-ray mapping analysis revealed the presence of the dentin bonding agent between the pin and dentin wall. The dentin bonding agent was not found in the dentinal cracks except at the crack orifice. SUMMARY: Within the limitations of this pilot study, the method of pin insertion had no direct bearing on the presence of dentinal cracks. The dentin bonding agent tested did not fill the entire space of dentinal cracks but did occlude their orifices and fill the spaces between pin surface and dentin walls in the pin preparation.

Cracked Tooth Syndrome↗
PubMed1983

A scanning electron microscope study of isolated glomeruli in glomerulonephritis.

Glomeruli from 48 cases of glomerulonephritis (Gn) were isolated and studied by means of the scanning electron microscope (SEM). Overall glomerular loss due to processing was 2.4%. SEM of these isolated glomeruli showed good preservation of glomerular structure. Changes of the podocyte cell body and its foot processes were noted and correlated with light microscopic morphology. Individual podocyte necrosis, variable foot process fusion and cell body swelling were seen in IgA nephropathy. Podocyte degeneration with separation from the glomerular basement membrane was evident in idiopathic minimal change Gn while idiopathic membranous Gn was characterized by globular swelling of the podocyte cell bodies. In focal sclerosing Gn, large spherical bodies arising from swollen podocyte cell bodies were frequently encountered. Innumerable microvilli and small spherical bodies characterized membranoproliferative Gn. Variable podocyte cell body swelling, microvilli and small spherical bodies were seen in cases of lupus nephritis. Taken alone, none of the SEM changes were diagnostic. However, when the type of the change, the severity and the combination of the changes were considered as a whole, they were indicative of what light microscopy might reveal and helpful in differentiating between idiopathic minimal change Gn and focal sclerosing Gn.

Basement Membrane↗
PubMed1981

A study of Dupuytren's tissue with the scanning electron microscope.

This study was designed to determine if structural changes in the palmar fascia in Dupuytren's disease, as viewed by the scanning electron microscope, might provide some information about the pathogenesis of this disease. The palmar fascia from seven uninvolved hands and from 21 patients with Dupuytren's disease was examined. There were distinct differences between normal and diseased collagen. The diseased tissue showed collagen that was more tightly bound and had a shorter wave pattern. In the Dupuytren's tissue the waves were frequently in a helix, but this was never seen in the normal tissue. The most striking differences were noted in the nodule, presumably because it appears first, followed by the cord proximal to the nodule (pretendinous cord). Similar but less obvious changes were noted in the cord distal to the nodule (central cord) presumably because it is last to form. These observations suggest a mechanism of contraction. The short wave length and helix formation of the collagen indicate shortening. If the concept of the myofibroblast as a contractile cell is accepted, the contraction of these cells in stepwise fashion could produce the changes in the structure of the collagen that have been observed and result in joint contracture.

Collagen↗
PubMed1996

Scanning electron microscope sizing of airborne fibre samples: a preliminary investigation into the effects of the variable inclination of fibres to filter surfaces.

The scanning electron microscope (SEM) method of fibre sizing assumes that all fibres lie flat on filters. This appears to be true for samples deposited from aqueous suspension, but in some airborne samples only about 60% of fibres lie flat on the filter surface and many of the rest are balanced at high angles to the filter surface. These inclined fibres will appear foreshortened when the filter surface is viewed in conventional orientation during SEM analysis. This could lead to an underestimation of fibre length and some fibres may be so foreshortened that they do not appear to fulfil the criteria of a fibre. The results of a preliminary investigation of the effects of variable fibre inclination in fibre counts and size data for two fibre types suggest that the SEM data do give an underestimate of the number, length and therefore volume of longer fibres in some samples. This suggests that it is important to consider fibre inclination when SEM analysis of airborne fibre samples is performed. Our preliminary observations suggest that is unlikely that it will be possible to derive widely applicable correction factors to allow for orientation effects.

Air Pollutants, Occupational↗
PubMed1989

Scanning electron microscopic evaluation of clinically cemented cast gold restorations.

Copper replicas were made of well-fitting, clinically cemented cast gold restorations. The replicas were scanned in the scanning electron microscope to measure the accuracy of fit at the margins. The margin discrepancies observed compared with findings of laboratory studies. Numerous microscopic cracks were found in the cervical enamel of these restored, vital, and asymptomatic teeth.

Cementation↗