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Results for “scanning electron microscope”

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PubMed1981

Blood flow and scanning electron microscope study on venous microvascular anastomoses with Nakayamas apparatus and manual suture.

Endothelium repair and blood flow changes after microvascular anastomoses in rabbit neck veins (diameter 1.5-2.5 mm) with either Nakayamas apparatus or manual suture were studied with scanning electron microscope and electromagnetical flowmeter. The healing process, which was very rapid, was examined at varying intervals from the day of surgery to four weeks postoperatively. Complete endothelialization was evident after one week. The blood flow was unimpaired by anastomosis with Nakayama rings, whereas in the suture group reduction in blood flow followed immediately after surgery. This reduction was however transient and blood flow was normalized two hours postoperatively.

Animals↗

PubMed1978

Hemangiosarcoma of the breast.--Case report with scanning electron microscopic study.

Hemangiosarcoma of the breast in a 22-year-old female was presented. She died of massive pulmonary metastasis and apparent internal hemorrhage from the involved liver by metastasis after 40 months of the illness. Intense scanning electron microscopic (SEM) study was undertaken on this lesion. At the same time, in order to compare SEM findings of angiosarcoma with several other benign disorders, the following lesions were chosen, namely, chronically-inflamed veins in the gastric submucosa, benign cavernous hemangiomas of the skin and liver, and organizing thrombi with papillary structures. Some of these lesions exhibited focal similarities in surface structures to those from angiosarcoma. Besides various characteristics by SEM in angiosarcoma, cell clusters protruding into the vascular cavity were found to be the most unique feature which we have never observed in any other lesions.

Adult↗

PubMed1978

A maturation change in the surface of cat articular cartilage detected by the scanning electron microscope.

The articular surface of the femoral condyle of kittens (2 days to 2 months old) and cats (6 months to 20 months old) was studied by examining air dried and critical point dried specimens in the scanning electron microscope. The surface of kitten cartilage was found to be populated by innumerable humps which were more prominent in air dried than in critical point dried specimens. Undulations and ridges were seen on air dried kitten cartilage, which was markedly shrunken and distorted, but undulations and ridges were absent from critical point dried specimens where shrinkage was more modest or even undetectable. The surface of the articular cartilage of 12 months and 20 months old cats was populated by innumerable pits. A rare hump in a pit was seen in specimens from the 12 months old cat, but not from the 20 months old animal. In 6--8 months old cats an intermediate situation prevails, for in some specimens pits were present on the posterior part of the condyle but humps and humps in pits were present on the anterior aspect. This study shows that the surface of young articular cartilage is populated by humps, but as the cartilage matures these formations are either transformed into pits or replaced by pits.

Age Factors↗

PubMed1975

Scanning electron microscope observations on the muscle innervation of Oikopleura dioica Fol (Appendicularia, Tunicata) with notes on the arrangement of connective tissue fibres.

Critical point dried and fractured appendicularia of the species Oikopleura dioica have been examined in the scanning electron microscope. The dorsal nerve cord with ganglion cells and peripheral nerve fibres could easily be observed. Thick peripheral nerve fibres leave the nerve cord as bilateral pairs at constant intervals along the tail. Most of these fibres branch from the naked nerve cord, but some evidently originate in ganglion perikarya bulging out from the nerve cord itself. These paired peripheral nerves always have elaborate end-arborizations on the medial surface of the lateral muscle cells. They are accordingly interpreted as motor axons. Some thinner peripheral nerve fibres originate at irregular intervals from both the nerve cord and the ganglion cells. Due to the numerous extracellular fibrils that connect the bilateral layers of the epidermal fins and the muscle cells to each other, these thin nerve fibres can seldom be traced to their termination. A few ones can, however, be traced ventrally between the notochord and the muscle cells and seem to end in singular bulb-like expansions. Clusters of synaptic vesicles are present in transmission electron micrographs of such nerves, and they are accordingly believed to carry efferent impulses. The extracellular fibrils are arranged in a highly ordered pattern with thick bundles crossing the gap between the structures to be interconnected and with numerous radiating insertions on the surface of the tissues.

Animals↗

PubMed1995

Three-dimensional organization of lymphatics in the dog small intestine: a scanning electron microscopic study on corrosion casts.

Casts of the lymphatics of the canine small intestine were made by direct injection of a low viscosity methacrylate resin into a large lymphatic in the submucosal layer, and observed under a scanning electron microscope. The lymphatics started with rod-like central lacteals in the villi of the jejunum and leaf-like ones in those of the ileum. The bases of the lacteals were connected by slender lymphatics forming a three-dimensional network, tentatively called the "superficial lamina propria lymphatic plexus". From this plexus, a few straight branches descended through the lamina propria to drain into a well developed "deep lamina propria lymphatic plexus", which was extended two-dimensionally closely above the lamina muscularis mucosae. From this plexus, a few short lymphatics extended and penetrated the muscularis mucosae and drained into the "superficial submucosal lymphatic plexus", a coarse mesh work of thick lymphatics. From this plexus, a few slender lymphatics descended to drain into a second lymphatic plexus, called the "deep submucosal lymphatic plexus", which extended two-dimensionally on the circular muscle layer. This deep submucosal plexus was a coarse network of thick knotty lymphatics. A large collecting lymphatic was occasionally seen running through the mesh. The tunica muscularis contained tubular lymphatics extending horizontally parallel to the muscle fiber, both circular and longitudinal.

Animals↗

PubMed1984

Pseudoexfoliation: epidemiology, clinical and scanning electron microscopic study.

The prevalence of pseudoexfoliation among patients of Sephardic origin was more than twice the expected when compared with the ethnic distribution of the population consulting the Rambam Medical Center eye clinic. A strong association between brown irises and pseudoexfoliation was noted. No uniform scanning electron microscope pattern was seen of the pseudoexfoliation.

Aged↗

PubMed1978

Nuclear surface complex as observed with the high resolution scanning electron microscope. Visualization of the membrane surfaces of the neclear envelope and the nuclear cortex from Xenopus laevis oocytes.

The nuclear envelope and associated structures from Xenopus laevis oocytes (stage VI) have been examined with the high resolution scanning electron microscope (SEM). The features of the inner and outer surfaces of the nuclear surface complex were revealed by manual isolation , whereas the membranes facing the perinuclear space (the space between the inner and outer nuclear membranes) were observed by fracturing the nuclear envelope in this plane and splaying the corresponding regions apart. Pore complexes were observed on all four membrane surfaces of this double-membraned structure. The densely packed pore complexes (55/micron2) are often clustered into triplets with shared walls (outer diameter = 90 nm; inner diameter = 25 nm; wall thickness = aproximately 30 nm), and project aproximately 20 nm above each membrane except where they are flush with the innermost surface. The pore complex appears to be an aggregate of four 30-nm subunits. The nuclear cortex, a fibrous layer (300 nm thickness) associated with the inner surface of the nuclear envelope, has been revealed by rapid fixation. This cortical layer is interrupted by funnel-shaped intranuclear channels (120-640 nm diam) which narrow towards the pore complexes. Chains of particles, arranged in spirals, are inserted into these intranuclear channels. The fibers associated with the innermost face of the nuclear envelope can be extraced with 0.6 MKI to reveal the pore complexes. A model of the nuclear surface complex, compiled from the visualization of all the membrane faces and the nuclear cortex, demonstrates relations between the intranuclear channels (3.2/micron2) and the numerous pore complexes, and the possibility of their role in nucleocytoplasmic interactions.

Animals↗

PubMed1987

Scanning Electron Microscope Studies of Interactions between Agaricus bisporus (Lang) Sing Hyphae and Bacteria in Casing Soil.

Relationships between the hyphae of Agaricus bisporus (Lang) Sing and bacteria from the mushroom bed casing layer were examined with a scanning electron microscope. Hyphae growing in the casing layer differed morphologically from compost-grown hyphae. Whereas the compost contained thin single hyphae surrounded by calcium oxalate crystals, the casing layer contained mainly wide hyphae or mycelial strands without crystals. The bacterial population in the hyphal environment consisted of several types, some attached to the hyphae with filamentlike structures. This attachment may be important in stimulation of pinhead initiation.

Journal Article↗

PubMed2003

Scanning electron microscope observations of new and used nickel-titanium rotary files.

The appearances of the tip sections of ProFile 0.04 taper and Lightspeed 25-mm long, ISO size 25, nickel-titanium rotary instruments were compared with a scanning electron microscope in the as-received condition and after one, three, and six simulated clinical uses to prepare mesial canals of extracted mandibular molars. For the used ProFile instruments, there was some flattening of the characteristic material rollover and minor apparent wear at the edges of the flutes, but there was little change in the tip regions of the used Lightspeed instruments. Deposits on the surfaces of the instruments were attributed to the manufacturing processes and the in vitro preparation of root canals in the extracted teeth. The simulated clinical use did not cause substantial changes in the regions of these two brands of rotary instruments that are involved in the clinical preparation of root canals.

Corrosion↗

PubMed1992

Scanning electron microscopic (SEM) examination of structures which supply subcapsular and midcortical region postglomerular microcirculation in sheep kidney.

Sheep kidneys were injected with polyester crystic (Dewilux 511-0196) and three dimensional forms of the structure forming the postglomerular microcirculation were examined by scanning electron microscope. During the examination of the afferent and efferent arterioles, a glomerulus with double efferent arterioles were examined and microdiverticular structures were observed in the terminal end of peritubular capillary plexus. It is concluded that these structures widen the surface area of the capillaries as a result of which diffusion across the capillary bed is facilitated.

Animals↗

PubMed1978

Scanning electron microscopic study of hyperacute rejection in the inbred rat.

Twenty skin-presensitised Lewis rats received kidney transplants from (Lewis X BN)f1 rats. Two grafts each were withdrawn at intervals from 1--120 min and examined using a scanning electron microscopic (SEM). A series of Lewis to Lewis isografts served as control. In hyperacute rejection at just 1 min spider-like fibrin fibres and platelets could be observed in small arteries, where the endothelium was severely altered. In these regions at 2 and particularly 5 min a fibrin network often contained platelet aggregates, mechanically altered erythrocytes as well as different kinds of leucocytes. This coagulation process progressed with time and resulted in a complete vascular occlusion at 30--60 min.

Animals↗

PubMed1979

Replica technique for scanning electron microscope examination of occlusal amalgam margins.

A new replicating technique, the modified adhesion relief method, was developed to investigate the marginal integrity of the occlusal surface of amalgam restorations over a period of years. The accuracy of the replicas was confirmed by scanning electron microscope comparison with the original teeth. The tooth to be studied need not be extracted. The technique makes it possible to continue the observation of restored teeth in the oral cavity for long periods. The technique does not require special equipment and is uncomplicated.

Cellulose↗

PubMedDate not supplied

Two-dimensional simulation and modeling in scanning electron microscope imaging and metrology research.

Traditional Monte Carlo modeling of the electron beam-specimen interactions in a scanning electron microscope (SEM) produces information about electron beam penetration and output signal generation at either a single beam-landing location, or multiple landing positions. If the multiple landings lie on a line, the results can be graphed in a line scan-like format. Monte Carlo results formatted as line scans have proven useful in providing one-dimensional information about the sample (e.g., linewidth). When used this way, this process is called forward line scan modeling. In the present work, the concept of image simulation (or the first step in the inverse modeling of images) is introduced where the forward-modeled line scan data are carried one step further to construct theoretical two-dimensional (2-D) micrographs (i.e., theoretical SEM images) for comparison with similar experimentally obtained micrographs. This provides an ability to mimic and closely match theory and experiment using SEM images. Calculated and/or measured libraries of simulated images can be developed with this technique. The library concept will prove to be very useful in the determination of dimensional and other properties of simple structures, such as integrated circuit parts, where the shape of the features is preferably measured from a single top-down image or a line scan. This paper presents one approach to the generation of 2-D simulated images and presents some suggestions as to their application to critical dimension metrology.

Journal Article↗

PubMed1996

The modification of the new type of end-to-side anastomosis between carotid arteries in rats: a technical and scanning electron microscopic study.

Modification of a type of end-to-side anastomosis that has been described before is studied. The recipient artery is occluded for only 3-4 minutes to complete the anastomosis by using only the running suture. The anastomotic site was studied by inspection and Scanning Electron Microscope (SEM) at different times after the operation on 30 rats.

Anastomosis, Surgical↗

PubMedDate not supplied

Natural course of experimental choroidal neovascularization: three-dimensional study with corrosion cast and scanning electron microscope.

OBJECTIVES: The details of the morphological features of choroidal neovascularization (CNV) remain unclear. The purpose of this study was to establish a CNV rat model and study the natural course of CNV using vascular casts and a scanning electron microscope (SEM). METHODS: Focal laser photocoagulation (argon green 50 mW, 0.04 s, 200 microm) was applied to Brown Norway pigmented rats. Choroidal vascular casts were prepared 1 and 3 days, 1 and 2 weeks, and 1, 3 and 6 months after laser photocoagulation. The choroidal casts were examined with a SEM. RESULTS: One day after photocoagulation, corrosion casts and SEM revealed complete defects of the choriocapillaris at the laser shot sites. One week after photocoagulation, small vascular buds originating from the damaged choriocapillaris were observed. Two weeks after photocoagulation, newly formed CNV originating from an individual laser burn was observed. One to three months after photocoagulation, these new vessels were connected to each other to form CNV networks. Six months later, some thin and atrophic vessels were observed in the CNV network. CONCLUSIONS: We succeeded in making fine corrosion casts of CNV formed by photocoagulation in pigmented rats and in demonstrating the details of CNV formation and regression. It is hoped that the results of this study will contribute to the development of a drug therapy for CNV and to the interpretation of diagnostic imaging of CNV in humans.

Animals↗

PubMedDate not supplied

Absence of bundle structure in the neocortex of the reeler mouse at the embryonic stage. Studies by scanning electron microscopic fractography.

The reeler mutant mouse is characterized by a derangement of the cerebral cortical structure due to abnormalities during the migration step at the embryonic stage. We have analyzed both the control and reeler cerebral cortex by means of scanning electron microscopic fractography. In the control cerebral cortex, the bundle formation was composed of fine fibers on which the migrating neuroblasts were attached perpendicular to the pial surface, whereas no bundle formation was observed in the reeler; instead, there was a fine meshwork of fibers surrounding the neuroblasts. The possible role of bundle formation in the normal cerebral cortex and the correlation between the inability of cells to migrate and the absence of bundle formation in the reeler is discussed.

Animals↗

PubMed1997

Scanning electron microscopical study of the neurofibrillary tangles of Alzheimer's disease.

Neurofibrillary tangles (NFTs) have been ultrastructurally studied by various methods, leading to several three-dimensional models of paired helical filaments (PHFs). In this study, we present the scanning electron microscopic findings of NFTs in an autopsy case of Alzheimer's disease and clarify the three-dimensional structures of NFTs. NFTs were clearly defined in freeze-cracked nerve cells and consisted of two types of filamentous structures, straight and helical filaments. Straight filaments measured from 20 to 25 nm in diameter and had a smooth surface. They were slightly bent but mostly straight with no constrictions. One type of straight filaments ran in a bundle in the same direction, another was intertwined to each other. Most of the helical profiles of filaments usually measured about 28 nm in diameter, with a distance of 100 nm between periodic constrictions. They seemed to consist of a pair of isodiametric filaments of 10 nm in diameter. In addition, two unusual types of helical filaments were occasionally observed. One comprised thick filaments of about 38 nm in diameter, with a distance of 100 nm between constrictions; these helical filaments appeared to consist of two or more strands. The other comprised thin helical filaments of about 20 nm in diameter and regularly constricted at an interval of 50 nm. All types of the helical filaments examined in this case were leotropic. This result supports a protofilament model of PHFs. Scanning electron microscopy using the freeze-cracked and maceration method is a useful and simple method for three-dimensional observation of the filamentous structures in NFTs.

Alzheimer Disease↗

PubMed1989

Tympanosclerosis: a scanning electron microscopic study.

Twelve specimens of tympanosclerosis were examined. Six were immediately fixed in 3% glutaraldehyde and 6 were obtained from the departmental collection of specimens in wax blocks which had previously been examined by light microscopy. Seven specimens were demineralized. The material was examined macroscopically, by light microscopy and by scanning electron microscopy to a magnification of x25,000. The microstructure of tympanosclerosis is an irregular three-dimensional collagen lattice, enclosing distinct, spherical, mineralized aggregates, housed in lacunar-like spaces. This lattice is continuous with the plaque surface which is an envelope, probably of proteinaceous material. The spherical calcified aggregates were absent from the demineralized specimens. There was no structural difference in the scanning electron microscopic appearances of specimens processed conventionally in 3% glutaraldehyde and those previously embedded in wax.

Adult↗