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At least 793 records · Page 44Linked to original sources

PubMed1992

Scanning electron microscopy of the small intestine during gluten-challenge in celiac disease.

The celiac disease syndrome is characterized by structural and ultrastructural alterations of the small intestine mucosa. According to criteria by European Society of Paediatric Gastroenterology and Nutrition, the conclusive diagnosis of celiac disease in children depends on the demonstration of histological relapse of the mucosa after reintroduction of gluten in the diet, as this syndrome is a permanent condition of gluten intolerance. Under these diseased conditions, the structure of the intestinal villi has been studied by light microscopy; morphological alterations were revealed only when the gluten challenge induced a clinical relapse. Scanning electron microscopy analyses of the intestinal mucosa in celiac diseased patients showed a strikingly uniform destruction of the villi with changes in their dimensions and arrangement. At high magnification the enterocytes were irregular in size and shape with a decrease and disruption of the glycocalyx. Reductions in length and density of microvilli were also clearly identified. Although these scanning electron microscopy findings could not demonstrate a relationship between the degrees of mucosal atrophy and the duration of the gluten challenge, they nevertheless revealed early stages of fine villous alterations that cannot be detected by the presently employed low resolution light microscopic techniques.

Autopsy↗

PubMed2000

In vitro MR imaging of hyaline cartilage: correlation with scanning electron microscopy.

OBJECTIVE: Our goal was to determine how the three-dimensional structure of hyaline cartilage affects its MR appearance and to correlate this appearance with detailed structural analysis using scanning electron microscopy and freeze-fracture sectioning techniques. MATERIALS AND METHODS: In vitro 7-T spin-echo MR images of hyaline cartilage specimens from four patients undergoing above-knee amputations were obtained parallel and perpendicular to the main magnetic field. Specimens were imaged with low- and high-power scanning electron microscopy after freeze fracturing. The corresponding images from both techniques were analyzed with specific attention to the three-dimensional structure of the cartilage, collagen fibril orientation, and respective changes in the MR appearance. RESULTS: Freeze fracturing of cartilage reveals a curved fracture plane. Expected changes in signal intensity predicted by the magic angle effect correlated with observed changes in signal intensity across the thickness of the sample. Changes in individual collagen fibril orientation did not correspond to MR layering. CONCLUSION: The three-dimensional organization of collagen in cartilage has a strong influence on the MR appearance of cartilage. This influence is caused by the restriction of water mobility and the resulting magic angle effect caused by curvature of the collagen network, possibly because of the influence on proteoglycan orientation.

Adult↗

PubMed1986

[Scanning electron microscopy and light microscopy studies on the retina of chick embryos in cell culture].

Histological and scanning electron microscopy studies (SEM) suggest a classification of neural elements into five main types: receptor cells, bipolar cells, horizontal, amacrine, and ganglion cells in dissociated cell cultures of the retina from 7 to 10 days old chick embryos. By use of SEM the development of the receptor cell inner segments was observed. At the same time many protrusions were noticed at the receptor cell surface. Specific synaptic contacts between the axons of the receptor cells and the dendrites of the bipolar neurons, as well as unspecific contacts between the pericarya of the receptor cells and other dendrites were demonstrated. The bipolar neurons showed smooth cell surfaces, however, the horizontal cells appeared rough on the cell surfaces. Müller cells were always found adjacent to the photoreceptor cells.

Animals↗

PubMed1985

Scanning electron microscopy as an analytical tool for the study of calcified intrauterine contraceptive devices.

Within the endometrial cavity intrauterine contraceptive devices (IUDs) become encrusted with cellular, acellular, and fibrillar substances. Scanning electron microscopy was used to study the crust. Cellular material consisted mainly of blood cells and various types of bacteria. The fibrillar material appeared to be fibrin which was omnipresent in the crust and formed a thin layer immediately over the IUD surface. X-ray microanalysis of the acellular component of the crust revealed the presence of calcium. No other major peaks were identified. Near the IUD surface characteristic calcium phosphate crystals were present. Their microanalysis showed peaks for calcium and phosphorus. X-ray diffraction of the crust however, showed it to contain only calcite. It is through the use of scanning electron microscopy that calcium phosphate has been detected in the IUD crust and a fibrillar layer has been visualized on the IUD surface. This study further demonstrates the effectiveness of SEM analytical techniques in the area of biomedical research.

Adult↗

PubMed1987

[Scanning electron microscopy studies of the structure of tissue in the cochlear opening of the cochlear aqueduct].

The structure of the internal and external tissue of the cochlear opening of the cochlear aquaeduct was examined by light microscopy on semithin sections and by scanning electron microscopy. The whole area is filled with a net of mesenchymal cells. The cell axes are randomly orientated inside the aquaeduct. On the outside of the cochlear aquaeduct fibrocytic tissue fills a space which is triangular in cross-section between the basal part of the cochlea wall of the tympanic scala and the middle portion of the round window membrane. In this area the direction of the net is uniform and it gives the impression of anchorage of the round window membrane on the perilymphatic side. The rim bordering the perilymphatic space is a dense net but not fully closed. The scanning electron microscopic pictures taken perpendicular to this border structure show clearly a texture of mesenchymal cells with open spaces. No closed "membrana limitans" was found. The possible function of the fixation of the round window membrane to the perilymphatic space giving rise to an asymmetric perilymph movement is discussed with regard to the physiology of sound transmission.

Animals↗

PubMed1999

Evaluation of initial attachment of human gingival fibroblast cells to biodegradable membranes in vitro by light and scanning electron microscopy.

Guided tissue regeneration procedures using resorbable membranes have become accepted therapy for treating periodontal defects. Resorbable collagen and synthetic polylactide and polyglycolide copolymer membranes have been found to support regeneration and preclude the need for surgical removal. This study was undertaken to assess and compare the initial attachment of human gingival fibroblast cells to four collagen-based membranes (fascia lata, fascia temporalis, dura mater, and Type I bovine collagen) and a synthetic polylactic acid-based membrane (resolut). Human gingival fibroblasts were grown from explants of normal tissue obtained during surgical reduction of retromolar tissues. Membrane specimens were placed in separate culture wells and incubated with fibroblasts for one hour. The number of adherent cells was evaluated by light microscopy using an ocular grid system and detailed examination was performed by scanning electron microscopy. The results of evaluation by light microscopy indicated that initial cell attachment was significantly less in the polylactic acid-based membrane group than in the collagen-based membrane groups (P < 0.01). However, no significant differences were found among the collagen membrane groups in terms of fibroblast attachment (P > 0.01). Scanning electron microscopy examination of fibroblasts cultured directly on barrier membranes indicated that the collagen-based membranes appeared to facilitate cell attachment, whereas the polylactic acid-based membrane exhibited a morphology that was not conducive to attachment of human gingival fibroblasts. Based on these limited in vitro results, it appears that collagen-based membranes offer greater potential than polylactic acid-based membranes for guided tissue regeneration at surgical sites.

Absorbable Implants↗

PubMed2000

Comparison of results of scanning electron microscopy and magnetic resonance imaging before and after administration of a radiographic contrast agent in the tendon of the deep digital flexor muscle obtained from horse cadavers.

OBJECTIVE: To analyze the tendon of the deep digital flexor (TDDF) muscle of the forelimb in horses by use of a contrast radiographic agent (gadopentate dimeglumine [Gd-DTPA/Dimeg]) and magnetic resonance imaging (MRI) and to determine the concentration of water protons in the tendons by use of MRI. SAMPLE POPULATION: 8 TDDF harvested from the forelimbs of 6 horse cadavers. PROCEDURE: Examinations were performed on the same portion of each tendon. Tendons were examined by use of two techniques: MRI before and after treatment with Gd-DTPA/Dimeg as well as scanning electron microscopy. RESULTS: Tendons did not have detectable signal intensity on MRI before treatment with Gd-DTPA/Dimeg; however, intravascular injection of Gd-DTPA/Dimeg allowed evaluation of the internal structure of the tendons Scanning electron microscopy images correlated well with images obtained by use of MRI before and after administration of Gd-DTPA/Dimeg. Localized spectra revealed the concentration of water protons in the TDDF. CONCLUSIONS AND CLINICAL RELEVANCE: The techniques used in this study provided information about internal organization of the TDDF in horses. Analysis of results revealed that the best technique involved vascular injection of contrast medium. Results of MRI correlated well with results for scanning electron microscopy. After administration of Gd-DTPA/Dimeg, MRI provided additional information about tendon morphologic characteristics. This technique may be of value for examination of tendons in lame horses.

Animals↗

PubMed1975

Scanning electron microscopy of the rat liver. Studies of the effect of taurolithocholate and other models of cholestasis.

The normal surface anatomy of rat hepatocytes, sinusoids, and bile canaliculi was examined by scanning electron microscopy following finger fracture of tissues that were perfused via the portal vein and fixed with 2.5% glutaraldehyde. These normal findings were contrasted with several models of cholestasis, including infusion of sodium taurolithocholate (TLC), bile duct ligation, and ethynyl estradiol treatment, in order to examine the effects of cholestasis on morphology of the bile canaliculus. TLC-induced cholestasis was associated with specific dilation and disruption of canalicular membranes, which corresponded to evaginations of pericanalicular ectoplasm observed by transmission electron microscopy, and suggested a direct toxic effect of the bile salt on membrane structure. Infusions of lithocholate sulfate or simultaneous infusions of TLC and sodium taurocholate prevented these severe abnormalities from occurring. Bile duct ligation produced progressive canalicular dilation (from 1 to 96 hr) and loss of microvilli, but did not result in the type of membrane changes produced by TLC. No significant changes in canalicular morphology were observed following ethynyl estradiol treatment. These studies demonstrate that scanning electron microscopy is a useful technique for the evaluation of both normal and abnormal hepatic surface morphology, and indicate that TLC produces a distinctive abnormality in the structure of the canalicular membrane, which was not seen in other models of cholestasis.

Animals↗

PubMed2002

Use of light and scanning electron microscopy to examine colonisation of barley rhizosphere by the nematophagous fungus Verticillium chlamydosporium.

Barley roots were readily colonised by the nematophagous fungus Verticillium chlamydosporium. Light microscopy (LM) but also low temperature scanning electron microscopy (LTSEM) revealed details of the colonisation process. Hyphae were found on the rhizoplane often with dictyochlamydospores. Hyphae of V. chlamydosporium penetrated epidermal cells, often by means of appressoria. A hyphal network was formed in epidermal and cortical cells. Likewise, hyphal coils were found within root cells next to transverse cell walls. Cortical cells were the limits of fungal colonisation, since no hyphae were seen in the vascular cylinder. Modifications of root cell contents (phenolic droplets and callose appositions) were common three weeks after inoculation with V. chlamydosporium. These features may indicate induction of plant defence reactions in late stages of root colonisation by the fungus. Both LTSEM and LM have proved extremely useful to describe root colonisation by the fungus. The results found may have implications in the mode action of nematophagous fungi against plant parasitic nematodes.

Animals↗

PubMed1988

Scanning electron microscopy of the upper urinary tract in transitional cell carcinoma of the renal pelvis.

Three nephrectomy specimens with transitional cell carcinoma (TCC) of the renal pelvis were thoroughly examined by both light and scanning electron microscopy. The tumours as well as the urothelium of the upper urinary tract were studied. In all three cases, extensive areas of the urothelium, even in places remote from the tumours, were found by scanning electron microscopy (SEM) to be covered by pleomorphic microvilli. This suggests that there is a widespread failure of differentiation of the urothelium to a much greater extent than can be appreciated by conventional light microscopy.

Adult↗

PubMed1976

Critical-point drying and gold sputtering as applied to scanning electron microscopy of human reproductive tissues.

Improved techniques have been developed for washing, pinning, fixation, dehydration and critical-point drying of tissues of female and male reproductive tracts, gametes, for viewing by scanning electron microscopy. The sputtering method, performed by an ion gun, is applied to shadow and produce a thin film of gold. Technical details and metal coating are noted which are suitable to improve images of surface ultrastructure of cilia and microvilli. Studies using scanning electron microscopy, histological and histochemical techniques, and cinematography are described.

Desiccation↗

PubMed1999

Cryo-techniques applied to stratum corneum with description of a new sample holder for cryo-scanning electron microscopy of freeze-fractured samples.

Stratum corneum structure greatly differs from that of the living epidermis and specific sample cryo-preparation techniques have to be used. Practical aspects of these cryo-techniques applied to stratum corneum are discussed. Emphasis is placed on scanning electron microscopy of cryo-fixed samples. A new sample holder designed for cryo-scanning electron microscopy of freeze-fractured stratum corneum is described.

Cryoelectron Microscopy↗

PubMed1985

Highlights of craniofacial morphogenesis in mammalian embryos, as revealed by scanning electron microscopy.

The craniofacial region has a complex developmental history. Some of the major morphogenetic events of this region are described for the mouse embryo, as revealed by the use of scanning electron microscopy. The three germ layers, the primitive building blocks of the embryo, are delineated during gastrulation. During neurulation, the outer ectodermal layer gives rise to the nervous system. Several other events occur concomitantly with neurulation. These include regional subdivision of the mesoderm, body folding, turning, and formation of the heart and gut. The craniofacial region, as well as a number of other regions or organ systems, undergoes major developmental events during the phase of embryogenesis called organogenesis. The visceral (branchial) apparatus develops around the primitive oral cavity and pharyngeal region of the foregut, and gives rise to many of the structures of the head and neck. The face develops from the first visceral arches and derivatives of the frontonasal prominence. The tongue also originates from tissue prominences derived from the visceral arches. The oral and nasal cavities are initially continuous broadly with one another. As a result of partitioning, paired nasal cavities develop and become largely separated from the underlying oral cavity. Scanning electron microscopy reveals much about the morphological events occurring during formation of the craniofacial region. However, emphasis in future studies should be placed on determining the underlying cellular and molecular mechanisms causing these events.

Animals↗

PubMed1985

Survival and growth of adult human oligodendrocytes in culture: scanning electron microscopy.

The oligodendrocytes in culture serve as an important model for the study of demyelination diseases. We have previously originated a method of isolating human oligodendrocytes. In order to establish their three dimensional morphology, scanning electron microscopy of the cultured oligodendrocytes was performed. The oligodendrocytes bulk isolated from adult human brain were maintained in culture for more than 2 months. At the various periods in culture, the cells were studied by scanning electron microscopy and immunofluorescence staining using marker antibodies for the identification of oligodendrocytes. The three dimensional organization and the surface morphology of the cultured oligodendrocytes were investigated. They displayed an extensive network of the cell processes and characteristic surface morphology.

Adult↗

PubMed2005

A vision-based, 3D reconstruction technique for scanning electron microscopy: direct comparison with atomic force microscopy.

High-resolution, detailed 3D reconstructions of biological specimens obtained from scanning electron microscopy stereo-micrographs and proprietary software were compared with Tapping-Mode AFM datasets of the same fields. The reconstruction software implements several original solutions including a neural adaptive point-matching technique, the ability to build an irregular triangulated mesh rather than a regular orthogonal grid, and the ability to re-map one of the original images exactly onto the reconstructed surface. The technique was applied to human nerve tissue to obtain 1,424 x 968-pixel, texture-mapped datasets, which were subsequently compared against 512 x 512-pixel AFM datasets from the same viewfields. Accounting for the inherent differences of the two techniques, direct comparison revealed an excellent visual match. The correspondence was also quantified by calculating the cross-correlation coefficient between corresponding altimetric profiles in SEM and AFM data, which consistently exceeded a figure of 0.9, with a rate of point mismatch in the order of 0.01%. Research is still underway to improve the robustness of the technique when applied to arbitrary images

Humans↗

PubMed1996

Scanning electron microscopy of heterochromatin in chromosome spreads of male germ cells in Schistocerca gregaria (Acrididae, Orthoptera) after trypsinization.

Chromosome spreads, prepared from testes of the desert locust Schistocerca gregaria, were analyzed using scanning electron microscopy (SEM) after varying periods of preincubation in trypsin. The emphasis of the study was on the appearance of heterochromatin. A trypsin pretreatment of 5 sec resulted in a smooth surface on the chromatin throughout and the heterochromatin was highly electron-emissive. The facultatively heterochromatic X chromosome was clearly visible in interphase spermatogonia and in pachytene and late prophase I spermatocytes. Chromomeres of autosomal bivalents could be recognized in pachytene cells. Centromeric heterochromatin segments were very prominent in autosomes of late prophase I spermatocytes and some chromosomes showed interstitial and telomeric bands. Longer trypsin treatment (10 sec) resulted in a fine globular surface on the chromatin; however, the electron emission of heterochromatic chromosome segments was lower under these conditions. The result of trypsin pretreatment of euchromatin differed only slightly from that of the heterochromatin. Extensive trypsin treatment (20 sec) did not alter further the relative electron emission of heterochromatin and euchromatin, but the regular globular appearance was lost, apparently owing to damage on the chromatin surface. The loss of electron emission from the centromeric heterochromatin of the autosomes and the facultatively heterochromatic X chromosome after extended trypsin treatment suggests a central role of proteins in mediating the heterochromatic status in meiotic chromosomes of the locust. Information obtained using scanning electron microscopy of chromosome spreads is complementary to that obtained by C-banding in that facultative heterochromatin is visualized with particular clarity.

Animals↗

PubMed2000

Scanning electron microscopy study of the choroid plexus in the monkey (Cebus apella apella).

The cells of the choroid plexus of the lateral ventricles of the monkey Cebus apella apella were examined through scanning electron microscopy at contributing to the description of such structures in primates. The animals were anesthetized previously with 3% hypnol intraperitoneally and after perfusion with 2.5% glutaraldehyde, samples of the choroid plexus were collected after exhibition of the central portion and inferior horn of the lateral ventricles. The ventricular surface of those cells presents globose form as well as fine interlaced protrusions named microvilli. Among those, it is observed the presence of some cilia. Resting on the choroid epithelial cells there is a variable number of free cells, with fine prolongations which extend from them. They are probably macrophages and have been compared to Kolmer cells or epiplexus cells, located on choroid epithelium. The choroid plexus of the encephalic lateral ventricles of the monkey Cebus apella apella at scanning electron microscopy is similar to that of other primates, as well as to that of other species of mammals mainly cats and rats, and also humans.

Animals↗

PubMed1996

Examination of external apical root resorption with scanning electron microscopy.

UNLABELLED: External apical root resorption may be evident histologically but not visible radiographically until it is advanced. If working length is determined without considering this resorption, overinstrumentation or overfilling may occur. OBJECTIVE: This study used scanning electron microscopy to examine the appearance and to compare the incidence of external apical root resorption in 40 teeth with differing pulpal and periapical diagnoses. STUDY DESIGN: After extraction, 46 roots were sectioned horizontally 6 mm from the anatomic apex and prepared for scanning electron microscopy examination. Photomicrographs were scored by two blinded independent examiners. Apical resorption was categorized as: none, partial, or complete. Presence or absence of a funneling appearance of the resorption was also recorded. RESULTS: Kruskal Wallis showed a significant difference in resorption between groups; teeth with irreversible pulpitis/normal periapex had the least resorption. Duncan's multiple range test found radiographic apical lesions to have more resorption than those without lesions; teeth with necrotic pulps had more resorption than those with vital pulps. CONCLUSION: Pulp necrosis with radiolucent apical pathosis is more likely to demonstrate resorption.

Chi-Square Distribution↗