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Results for “Microscopy, Electron, Scanning”

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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↗

PubMed2002

Structural aspects of the extracellular matrix of the tendon: an atomic force and scanning electron microscopy study.

The mutual interactions of small proteoglycans with collagen fibrils in the extracellular matrix remain to be completely understood. The present research investigated the extracellular matrix of the rat tail tendon by atomic force microscopy (AFM) as well as by scanning electron microscopy (SEM). Observations showed simply dehydrated specimens made of large heterogeneous fibrils, tightly packed in mutual contact with no visible interfibrillar spaces. Proteoglycans usually extended onto neighboring fibrils, forming an intricate interfibrillar weaving highly sensitive to chondroitinase digestion. Pre-treatment with cupromeronic blue only affected the proteoglycans side chains, which appeared better preserved but somewhat thickened. Observation of hydrated specimens by AFM confirmed the close packing of collagen fibrils and the abundance of collagen-bound proteoglycans. Interfibrillar bridges were only occasionally observed in this tissue, whose fibrils are instead tightly bound together by proteoglycans in a structure quite consistent with its functional requirements. The molecular machinery responsible for these interactions is the subject of ongoing research.

Animals↗

PubMed1981

Low temperature scanning electron microscopy of dog and guinea-pig hyaline articular cartilage.

Fifty seven blocks of cartilage excised from the femoral condyles of 20 beagle dogs, and whole lower ends of 5 guinea-pig femora, were examined at -195 degrees (78 K), by scanning electron microscopy. The unfixed tissue, taken into slushy nitrogen at -210 degrees (63 K), was not exposed to atmospheric air after quenching and remained fully hydrated throughout long periods of observation. Images susceptible to analysis were obtained from washed and from unwashed cartilage surfaces. Preliminary coating with gold or with aluminium, known to be possible without exposing cold cartilage surfaces to changes in temperature likely to cause water loss by sublimation, was valuable in minimising charging and in facilitating the recording of electron images at higher magnifications. Although examination was possible without coating, the resultant images were of low resolution. Microscopy revealed a pattern of secondary surface irregularities of tertiary elevations closely resembling those seen by the conventional scanning electron microscopy of fixed, dehydrated hyaline cartilage. However, the pattern of tertiary surface structures was predominantly that of elevations, not of hollows. Quaternary surface ridges were common on the surfaces of excised dog cartilage blocks and were not seen on the surfaces of guinea-pig cartilage which remained on the femoral condyles.

Animals↗

PubMed1996

A new morphological classification during follow-up in patients with celiac disease: a three-dimensional observation by scanning electron microscopy.

The structure and ultrastructure of the villi of small intestinal mucosa was examined in 237 duodenal or jejunal biopsies taken from children with active celiac disease and during gluten-free diet. All biopsies were processed for light and scanning electron microscopy. Conventional histology showed four different morphological aspects: total and subtotal villous atrophy in patients on unrestricted diet, partial villous atrophy and normal mucosa during gluten-free diet. Scanning electron microscopy demonstrated that in active celiac disease the severity of the intestinal lesions was related to individual vulnerability to gluten. Our results showed that during dietary treatment the process of mucosal healing was constant and strictly time-dependent. Furthermore, the ultrastructural examination has been relevant in evaluating the evolution of the villous regeneration. In this study a classification regarding the healing process of the small intestinal mucosa correlated with the time of start of dietary therapy is proposed.

Adolescent↗

PubMedDate not supplied

Scanning electron microscopy of aortic medial changes in aortic ascending dilatation.

The study of cystic cavities and collagen fibers fragmentation is useful to for a better knowledge of pathogenesis and surgical therapy of medial ascending aortic degeneration. Thus, the aim of this study was to describe by scanning electron microscopy the surfaces and shape of the cysts, measure their area, and identify microcystic spaces related to this degenerative disease. Scanning electron microscopy analysis was performed in 16 out of 36 patients who underwent surgery for ascending aorta dilatation with associated aortic valve disease. The aortic medial wall showed a cribrose appearance at low magnification (x50-100) and the intima was effuse. At high magnification (x500-2000), small cavities (clefts) lined by normal or fragmented elastic fibers and large cavities (pseudocystes) with anfractuous borders lined by fragmented elastic fibers and smooth muscle cells were observed. Furthermore, in the outer media wall microvessels lined by endothelium were also observed. These changes were lacking or less pronounced in normal aorta. SEM allows one to better identify the pathological cavities and to differentiate them from microvessels. These pathological cavities are more numerous and larger in the convexity than in the concavity of the aorta in according to our previous morphological and morphometric findings in asymmetrical aorta dilatation.

Aorta↗

PubMedDate not supplied

[Study of microinjuries to hair cuticle of human head by scanning electron microscopy].

The author presents the data on microclues in the free edges of hair cuticles of human head: microinjuries, microdefects (cracks, breaks, clefts, large and small waves) in representatives of Asia, Africa, Latin America, and Eastern Europe. The studies were carried out by scanning electron microscopy. Microinjuries of cuticle cells forming during hair combing by different types of combs and as a result of "permanent" curling are described. Scanning electron microscopy at the optimal magnification of x 3000 is a highly informative method for investigating microinjuries to the hair cuticle as additional signs in expert evaluation of the hair.

Forensic Anthropology↗

PubMed1993

Primordial germ cells in the primitive streak stages chick embryo as studied by scanning electron microscopy.

Chick embryo primordial germ cells (PGCs) at stages 4-8 were localised in the late hypoblast layer. PAS staining confirmed their distribution in a large arc at the anterior border of the area pellucida/area opaca. By scanning electron microscopy the PGCs were seen as spherical cells within the late hypoblast layer. Individual cells separated from this layer and collected in groups of 2-10 in shallow pockets in the hypoblast layer prior to their migration. The pockets containing PGCs were clearly visible by light and scanning electron microscopy and demarcated the germinal ridge at stages 4-8.

Animals↗

PubMed1996

Scanning electron microscopy of fragmentary marker chromosomes observed by light microscopy.

To study the fine structure of fragmentary marker chromosomes, we performed scanning electron microscopy (SEM) on samples isolated from two carriers (Case 1: 46, XY/47, XY, +mar/48, XY, +mar, +mar; Case 2: 47, XY, +mar). In both cases, light microscopic observation revealed that marker chromosomes lacked a centromere and were fragmented in appearance. However, SEM observation of the metaphasic cells in both cases showed three variations. One variation was a structure that seemed to be metacentric, another was a structure that seemed to be submetacentric, and the remaining one was essentially fragmentary. However, neither the usual chromatid nor centromere formations were observed in the metacentric-like and submetacentric-like structures, even when both cases were observed by SEM. Moreover, the marker chromosomes of the boy of Case I, who suffered from various clinical troubles, included a greater population of metacentric-like or submetacentric-like structures than of essentially fragmentary structures. The marker chromosomes of the fetus of Case 2, who suffered from no clinical problems, included a much greater population of essentially fragmentary structures than metacentric-like or submetacentric like structures. Therefore, SEM observation of fragmentary marker chromosomes that are visible on light microscopy might be used to define specific structures. Moreover, SEM observation might provide clinical criteria relating to the pathogenesis of fragmentary marker chromosomes found on light microscopy.

Abnormalities, Multiple↗

PubMed1988

[Pili annulati. A scanning electron microscopy study].

A case of ringed hair studied by light and electron microscopy is reported. The patient, a 20-year old girl, had been presenting with the hair abnormality since birth. At naked eye examination the hairs were dry, 6 to 7 cm long, and they showed dull and shining areas giving the scalp hair a scintillating appearance (fig. 1). Several samples of hair were taken and examined by light microscopy under white and polarized light. Hair shafts and cryo-fractured surfaces were examined by scanning electron microscopy. RESULTS. 1. Light microscopy. Lesions were found in every hair examined. There were abnormal, opaque and fusiform areas alternating with normal areas all along the hair shaft (fig. 2). The abnormal areas resulted from intracortical air-filled cavities. Fractures similar to those of trichorrhexis nodosa were found in the opaque areas of the distal parts of the hairs. 2. Scanning electron microscopy. A. Hair shaft surface. The abnormal areas showed a longitudinal, "curtain-like" folding of the cuticular cells which had punctiform depressions on their surface and worn free edges (fig. 4, 5, 6); trichorrhexis-type fractures were seen in the distal parts of the hair shafts (fig. 7, 8). Normal areas regularly presented with longitudinal, superficial, short and non-systematized depressions (fig. 9); the cuticular cells were worn, and there were places where the denuded cortex showed dissociated cortical fibres (fig. 10).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1976

Scanning electron microscopy of the bronchial mucosa in some lung diseases using bronchoscopy specimens. A pilot study including cases of bronchial carcinoma, sarcoidosis, silicosis and tuberculosis.

In order to study the lung defence mechanisms and the mucociliary transport system scanning electron microscopy was performed on biopsy specimens obtained at bronchoscopy under local anaesthesia. There were great variations in the appearance of the cilitated epithelium from the large bronchi in 40 patients with bronchial carcinoma, sarcoidosis, silicosis, tuberculosis and other lung diseases. Areas with a low frequency of cilia were observed mainly in granulomatous disorders, and in silicosis, atypical cilia occurred abundantly. Squamous metaplasia with a complete loss of cilia was found in chronic bronchitis, bronchial carcinoma, after radiotherapy and in two of seven cases of sarcoidosis. Scanning electron microscopy seems to be an excellent method for studying the surface of the bronchial epithelium in many lung diseases, and may prove to be helpful in occupational medicine.

Adult↗

PubMedDate not supplied

Imaging of anisotropic cellulose suspensions using environmental scanning electron microscopy.

The effect of concentration on anisotropic phase behavior of acid-hydrolyzed cellulose suspensions has been examined using conventional polarizing microscopy and the novel technique of environmental scanning electron microscopy (ESEM). Microcrystalline cellulose dispersed in water formed biphasic suspensions in a narrow concentration range, 4-12 wt % for a suspension pH of 4, where the upper and lower phases were isotropic and anisotropic (chiral nematic), respectively. It is known from previous work that within the biphasic regime total suspension concentration affects only the volume fractions of the two phases, not phase concentration or interfacial packing. As the total suspension concentration surpassed the upper critical limit (c), however, a single anisotropic phase of increasing concentration was observed. It was evident from polarizing microscopy that the chiral nematic pitch of the anisotropic phase decreased with increasing concentration, which has been attributed to a reduction in the electrostatic double layer thickness of the individual rods, thus increasing intermolecular interactions. Chiral nematic textures were also visible using ESEM. This technique has the advantage of studying individual rod orientation within the liquid crystalline phase as it permits the high resolution of electron microscopy to be applied to hydrated samples in their natural state. To our knowledge this is the first time such lyotropic systems have been observed using electron microscopy.

Anisotropy↗

PubMed2003

Vascular system of intramural leiomyomata revealed by corrosion casting and scanning electron microscopy.

BACKGROUND: The vascular system of leiomyomata, the most common benign tumours in women, is an important factor controlling development and growth of the tumour. It has not been, however, investigated morphologically using the best currently available technique, corrosion casting combined with scanning electron microscopy. METHODS: Myomatous uteri collected upon autopsy were perfused via afferent vessels with fixative followed by Mercox resin and corroded after polymerization of the resin. The obtained vascular casts visualizing all vessels including capillaries were examined using scanning electron microscopy. RESULTS: The smallest (1-3 mm) fibroids were avascular, in larger ones (<1 cm) a few small vessels invaded the lesion from the periphery. The largest tumours (>1 cm) contained irregular networks of blood vessels with density similar to or lower than that of normal myometrium. Such tumours were surrounded by an extremely dense vascular layer ('vascular capsule') which was the source of larger vessels supplying and draining the tumour. CONCLUSIONS: During development of leiomyoma, the pre-existing blood vessels undergo regression and new vessels invade the tumour from the periphery, where intense angiogenesis, probably promoted by growth factors secreted by the tumour, leads to the formation of a 'vascular capsule' responsible for supply of blood to the growing tumour.

Adult↗

PubMed1990

Identification of Actinobacillus actinomycetemcomitans by gold immunolabeling and scanning electron microscopy.

Recent evidence suggests that dental plaque is not a homogeneous bacterial mass but, on the contrary, specific bacterial morphotypes and species may be preferentially located within certain microenvironments. The aim of the present study was to develop combined gold immunolabeling and scanning electron microscopic (SEM) techniques for the identification of periodontal pathogens in subgingival dental plaque and on the root surfaces of extracted teeth. Suspensions of pure A. actinomycetemcomitans cultures or suspensions of A. actinomycetemcomitans mixed together with other oral bacteria were prepared, labeled with goat anti-rabbit IgG conjugated with 5 nm or 40 nm colloidal gold particles, and observed by SEM using both secondary and back-scattered imaging. Scanning electron microscopy demonstrated that the A. actinomycetemcomitans bacterial cell surface was specifically labelled. There was no cross-reaction with any of the other bacterial morphotypes. Only the labeled A. actinomycetemcomitans were visible in mixtures examined by back-scattered imaging scanning electron microscopy. The combined techniques of gold immunolabeling and SEM may, therefore, be useful in identifying A. actinomycetemcomitans in subgingival plaque samples and on the root surfaces of extracted teeth as well as in studies of bacterial ecology in dental plaque, in general.

Actinobacillus↗

PubMed1986

Scanning electron microscopy of conjunctival surfaces in patients with ocular cicatricial pemphigoid.

The conjunctival surfaces of ten patients with active, ocular cicatricial pemphigoid, three patients with drug-controlled ocular cicatricial pemphigoid, and six patients with normal conjunctivas were studied using scanning electron microscopy. A homogeneous granular sheet of amorphous mucin-like material was observed covering extensive areas of the conjunctiva in eight of ten patients with active ocular cicatricial pemphigoid. This sheet of amorphous material was absent on drug-controlled ocular cicatricial pemphigoid and normal conjunctival specimens. Our study demonstrates that patients with active ocular cicatricial pemphigoid possess ocular surface mucus that appears thicker and more continuous than normal ocular mucus when observed with scanning electron microscopy. This observation is in agreement with clinical observations of thick mucus strands in the inferior fornix of patients with active ocular cicatricial pemphigoid.

Conjunctiva↗

PubMed1997

[Study on the organization of chromatin and chromosome in mouse spermatogenic cells by scanning electron microscopy].

It remains unclear about the intermediate construction of chromosome due to its highly compact nature and the limitation in methods. The present study was designed to investigate the construction of chromatin and mitotic chromosome in situ with scanning electron microscopy. Mouse testes were selected as the material, because of in which the spermatogenic cells divide actively and successively to form the sperm. Such a feature would be able to study the structure of mammalian chromatin and chromosomes along with the change of nuclear cycle. The animal were perfused with 200 ml of 0.075 mol/L KCl hypotonic solution to remove blood and placed for 15-20 min on ice followed by 0.5% glutaraldehyde and 0.5% formaldehyde for fixing. Through treated by the routine process of fractured and freeze dried with t-butyl alcohol, the specimens were then coated with a 3 nm thick platinum and observed with Hitachi S-430 scanning electron microscopy. It was found that the hypotonic treatment with 0.075 mol/L KCl solution was suit for demonstrating the nuclear structure, when the organelles were well preserved. The chromatin fibers of 10-30 nm and 80-125 nm in diameter could be recognized in the interphase nuclei, which were arranged losely at the region of euchromatin, and folded with each other into chromatin masses at the region of heterochromatin, while the chromatin fibers with the diameter of 80-125 nm often could be viewed on the mitotic chromosomes. Since its presence in interphase nuclei and mitotic chromosomes, it was considered that the chromatin fibers with 80-125 nm in diameter might play a role in the condensation of chromosome, serve as a type of the intermediate structure.

Animals↗

PubMed1996

Dynamics of salivary secretion studied by confocal laser and scanning electron microscopy.

Plasma membrane events during secretion of the parotid and submandibular glands of humans and rats were observed in living cells by confocal microscopy and from the cytoplasmic side by scanning electron microscopy after removal of the cell organelles by the OsO4 maceration method. These new microscopic techniques revealed in acinar cells two distinct exocytosis-endocytosis coupling mechanisms elicited in response to different secretory stimuli. Beta-adrenergic stimulation with isoproterenol and its second messenger analog dibutyryl cyclic AMP evoked exocytosis after which fused granule membranes were individually removed from the luminal plasma membrane within several minutes. On the fused membrane area, small endocytotic vesicles about 100-150 nm in diameter were abundant. Muscarinic stimulation with carbachol also induced exocytosis, but in this case the fused granule membranes coalesced to form enlarged invaginations which stayed on the luminal membrane for more than 30 min. These invaginations, almost devoid of small endocytotic vesicles, were then pinched off from the luminal membrane and dispersed into the cytoplasm in the form of light microscopically detectable vesicles. After treatment with isoproterenol and carbachol, acinar cells exhibited different distributional changes of F-actin around the fused membrane area, suggesting the involvement of microfilaments in regulating the membrane events following exocytosis.

Actin Cytoskeleton↗