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Results for “scanning electron microscope”

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PubMed1986

A scanning electron microscopic investigation of accessory foramina in the furcation and pulp chamber floor of molar teeth.

Observations of the pulp chamber floor and furcation surface of human maxillary and mandibular first and second molars were made with the scanning electron microscopic to determine the incidence, size, and location of patent accessory foramina. Accessory foramina on both the pulp chamber floor and the furcation surface were found in 36% of maxillary first molars, 12% of maxillary second molars, 32% of mandibular first molars, and 24% of mandibular second molars. Mandibular teeth had a higher incidence (56%) of foramina involving both the pulp chamber floor and furcation surface than did the maxillary teeth (48%).

Dental Pulp Cavity↗

PubMed1982

Scanning electron microscopic observation of glial cells following xenon arc photocoagulation.

The retinal tear produced in rabbits by aspirating the vitreous body was treated by means of photocoagulation, and its time-course changes were observed under a scanning electron microscope. Four weeks after photocoagulation, the surface of the retina surrounding the tear began to swell glial cells, that protruded with the lapse of time. About 6 weeks after photocoagulation, the glial cells perforated the internal limiting membrane of the retina and came out its surface, so that the glial cell processes and the cell perikaryon could be clearly observed morphologically. The findings showed that the glial cells are fibrous astrocytes. Seven weeks after photocoagulation, glial cells proliferated even in the retinal tear and, furthermore, glial cells in the space between the retinal tear and the retina surrounding it joined together by intertwining their processes to form a network, which seemed to play a certain role in repairing the tear.

Animals↗

PubMed1992

Development of the chick tongue. A scanning electron microscopical investigation.

With the aim of clarifying certain morphological aspects of lingual development, chick tongues between the 8th day of incubation and hatching and also during the early postincubation period were investigated by means of the Scanning Electron Microscope. During this time, the tongue anlage underwent some remarkable morphogenetic changes, mostly involving the superficial epithelium but also including the appearance of the lingual glands at the level of the lingual root. With regards to the epithelium, it was possible to observe that in the first days of the incubation period examined, the superficial cells appeared dome-shaped, with microvilli on the apical surface; later they tended to become more flattened, and the microvilli were replaced by a thick net of microplicae. During the final days of incubation, and after hatching desquamative phenomena became evident. At no site of the tongue rudiment were taste buds ever observed, possibly because of the different functional role played by the avian tongue in comparison with that of the mammals.

Age Factors↗

PubMed1985

The organization of collagen in cryofractured rabbit articular cartilage: a scanning electron microscopic study.

Adult rabbit articular cartilage was prepared for scanning electron microscopy using, in order, glutaraldehyde fixation, enzymatic removal of proteoglycan, dehydration in ethanol, cryofracture in liquid nitrogen, and critical-point drying. Enzymes were effective in fixed material. Fixation, cryofracture, alignment of fracture surfaces with "split lines," and retention of subchondral bone were found to be necessary steps for the preservation of collagen detail. The fibrous framework was found to be similar to that proposed by Benninghoff and favored by more recent phase-contrast microscopic studies. Vertical fibers extending from subchondral bone and a network of tangentially oriented superficial fibrils converge in the transitional zone. No random layer is seen. Pericellular capsules interdigitate with the vertical fibers. When cartilage is prepared in a manner that minimizes tissue damage, scanning electron microscopy provides useful, unique information.

Animals↗

PubMed1996

Biomaterial-induced alterations of human neutrophils under fluid shear stress: scanning electron microscopical study in vitro.

Morphological changes of human polymorphonuclear neutrophils (PMN) adhering to hydrophilic (glass) and hydrophobic (FEP-Teflon, polyethylene, polypropylene) surfaces were studied in a parallel-plate flow chamber at the light and scanning electron microscopical levels. The PMN were exposed to a shear stress of 0.19 Pa (1.9 dynes cm-2) or were allowed to adhere without the stress component (static control) during 30 min for all four biomaterials. Observation by light microscopy was performed in situ in the flow chamber at 1, 5, 10, 15, 20, 25 and 30 min. The total number of adherent cells as a function of time and the activation status of the population on the basis of morphological criteria were determined. On the hydrophilic material adhesion of activated PMN was significantly higher (P < 0.05) than on the more hydrophobic surfaces. This effect was most pronounced for the adhesion of neutrophils to glass and polypropylene (PP). Polyethylene (PE) showed only minor adhesion rates. Scanning electron microscopy revealed details of cell shape changes and permitted a more precise classification of populations of neutrophils based on distinctive shapes. As PMN were exposed to shear stress on glass, the majority of cells exhibited surface veils, ridges and ruffles, suggesting a high level of cell migration. In this case, on polymeric surfaces the presence of filopodial networks (FEP-Teflon) and ameoboid cell shapes (PP and PE) was noted. The results suggest that a low shear stress, as well as various chemical and physical properties of biomaterial surfaces, are together responsible for differentiation of PMN populations on solid substrata.

Biocompatible Materials↗

PubMed1979

Some scanning electron microscopic observations of the ependymal surface of the ventricles of hydrocephalic Hy3 mice and a human infant.

Two hydrocephalic Hy 3 mice and an infant with hydrocephalus and the Arnold-Chiari malformation were examined with the scanning electron microscope. Both mice had advanced hydrocephalus but had normal appearances in the basal regions of the ventricles. However, as the ventricular walls were ascended first the cilia gradually disappeared, then the microvilli, and finally on the roof of the ventricle the ependymal cells disappeared leaving the subependymal layers exposed. The infant had mild hydrocephalus and normal ependymal appearances. The most likely explanation of these findings is that they are a consequence of raised intracranial pressure, and are not the cause of hydrocephalus.

Animals↗

PubMed2002

Internal root resorption studied by radiography, stereomicroscope, scanning electron microscope and computerized 3D reconstructive method.

AIM AND METHODOLOGY: Two cases of internal tooth resorption were examined. A mandibular premolar and a mandibular canine were studied after they were extracted using radiographs, a stereomicroscope (SM) and a scanning electron microscope (SEM). Lastly, 3D images of the sectioned teeth were obtained(3D). RESULTS: Radiographically, internal root resorption was shown as a uniform radiolucency. By SM examination, an extensive destruction of dentin was seen, while, by SEM examination, a disappearance of dentinal tubules was clear. The 3D reconstructive method revealed a circumscribed, oval-shaped defect that did not perforate the cemental layer. CONCLUSIONS: Internal root resorption is a rare remodeling process that can be studied using different experimental methods.

Bicuspid↗

PubMed1981

Scanning electron microscopic study of normal human glomerulogenesis and of fetal glomeruli in congenital nephrotic syndrome of the Finnish type.

Kidneys from 5 normal fetuses and 3 with congenital nephrotic syndrome gestational age of 13 to 24 weeks, were studied under a scanning electron microscope. Differentiation of the visceral epithelial cells was observed in normally developing glomeruli. The originally cuboidal, smooth epithelial cells first flattened and acquired cytoplasmic buds on the cell margin. The buds gradually grew longer and branched out to form regular interdigitating foot processes. In the most mature glomeruli the majority of the visceral epithelial cells were trabeculated and the cytoplasmic processes were tightly wound around the glomerular capillaries. In the glomeruli of specimens from fetuses with congenital nephrotic syndrome the epithelial differentiation was different. The individual epithelial cells varied in size and shape and formed irregular cell groups. The cytoplasmic processes of visceral epithelial cells were shortened and flattened. Also, there was a marked loss of interdigitation of adjacent processes. The findings confirm previous transmission electron microscopic observations of pathological foot processes in glomeruli of fetuses with congenital nephrotic syndrome and show that the differentiation of the visceral epithelial cells is abnormal prior to the formation of the final interdigitating processes.

Female↗

PubMed1983

Correlation between chemiluminescence response and rate of zymosan uptake by rat alveolar macrophages. Scanning electron microscope observations.

The rate of particle uptake by rat alveolar macrophages (AM) exposed to zymosan (mean number of zymosan particles becoming bound to 100 cells at a fixed time interval) was determined with the aid of the scanning electron microscope (SEM). The intensity of the chemiluminescence (CL) emitted by the AM on addition of zymosan, was measured concomitantly. During the whole course of CL emission, all the particles were found to be either attached or engulfed, but not ingested by the AM. A good correlation was obtained between the time dependence of CL intensity and that of the rate of particle uptake, both reaching a peak value at about 5 min after exposure. It is therefore assumed that the CL emitted by AM exposed to zymosan reflects the attachment and engulfment stages of phagocytosis.

Animals↗

PubMed1979

[Scanning electron microscope study of the lung epithelium of the rabbit during ontogenesis].

The development of the bronchial and alveolar epithelium was observed in rabbits from the 15th day post conception until the time of birth with the scanning electron microscope. In the pseudoglandular phase, primitive bronchi proliferate in the mesenchyme. The epithelial cells are not differentiated and have single cilia. After retraction of these single cilia cell differentiation begins. Flat cells densely populated with cytopodia can be recognized on the 22nd day, ciliated cells on the 23rd day post conception. Both are located in the bronchi near the hilus. In the canalicular phase of development, the differentiation of the mucoid cells and the Clara-cells begins. The interstitial connective tissue develops more and more capillaries. The alveolar phase begins around the 26th day p. c. The lung capillaries reach the alveolar epithelial cells and arrange themselves directly beneath the epithelial basement membrane. This "alveolarization" of the lung tissue starts in the centre of the lung lobules and proceeds to the periphery. After the 26th day post conception the alveolar epithelial cells retract their single cilium and at the same time become type I or type II pneumocytes. The undifferentiated entodermal stem cell of the alveolar epithelium is the pneumoblast.

Animals↗

PubMed1982

[A scanning electron microscopic study of the tracheal mucosa damage after long-term translaryngeal intubation (author's transl)].

Tracheal mucosa tissue obtained by tracheotomy from 23 patients who had been intubated between 4 to 20 days was examined in the scanning electron microscope. In spite of different intubation periods almost identical tissue defects with extensive areas of epithelial degeneration reaching as far as the basal lamina were found. In contrast, patients with short-term intubation, i.e. during intubation anaesthesia, showed no mucosal changes in the areas studied. The expected damage in the lower trachea caused by the cuff of the intubation tube is described and the dangers of prolonged intubation are discussed.

Female↗

PubMed1991

Scanning electron microscopic study of the splenic vascular casts in common tree shrew (Tupaia glis).

Splenic vascular casts of the common tree shrew, Tupaia glis, were constructed with Batson's No. 17 plastic mixture and studied with the scanning electron microscope (SEM). Fifteen adult animals of both sexes, weighing between 120 and 180 g were used. Under ether anaesthesia, each animal was injected with 0.05 ml heparin intracardially; the right atrium was cut open and then 250 ml of 0.9% NaCl, followed by 50 ml of 10% neutral formalin, (in four animals) was injected through the left ventricle. Plastic mixture was injected through the same opening. After complete polymerization of the plastic, the spleen and surrounding tissues were removed and macerated in 40% KOH. The air-dried casts were then coated with carbon and gold before viewing and photographing under SEM at 15 kV. It was found that the splenic arteries penetrated deep into the organ before they divided into trabecular arteries and divided again into central arterioles. Each central arteriole sent out 15 to 30 radiating arterioles, called penicillar arterioles, and further divided into smaller vessels entering the marginal zone and red pulp. In this area each arteriole continued directly into either marginal or red pulp sinusoids. The sinusoids emptied into pulp venules which joined to form trabecular veins. Most of the trabecular veins travelled to the cortical area underneath the splenic capsule before approaching the hilum, where they finally drained into splenic and short gastric veins. It is likely that the spleen of the common tree shrew has a closed circulation.

Animals↗

PubMedDate not supplied

Experimental data and model simulations of beam spread in the environmental scanning electron microscope.

This work describes the comparison of experimental measurements of electron beam spread in the environmental scanning electron microscope with model predictions. Beam spreading is the result of primary electrons being scattered out of the focused beam by interaction with gas molecules in the low-vacuum specimen chamber. The scattered electrons form a skirt of electrons around the central probe. The intensity of the skirt depends on gas pressure in the chamber, beam-gas path length, beam energy, and gas composition. A model has been independently developed that, under a given set of conditions, predicts the radial intensity distribution of the scattered electrons. Experimental measurements of the intensity of the beam skirt were made under controlled conditions for comparison with model predictions of beam skirting. The model predicts the trends observed in the experimentally determined scattering intensities; however, there does appear to be a systematic deviation from the experimental measurements.

Journal Article↗

PubMed1980

Scanning electron microscopic observations of the surface of the initial lesion in experimental streptococcal endocarditis in the rabbit.

The surfaces of vegetations in the first 24 h after initiation of experimental streptococcal endocarditis in rabbits were examined systematically using the scanning electron microscope (SEM). Most of the observed fields were occupied by amorphous material but with the SEM very small features of interest could be identified. Erythrocytes were more frequent before 6 h and leukocytes were rarely seen. Bacteria were significantly more frequent at 10/15 min and at 20 h. It is suggested that bacteria lodge on the vegetation surface following inoculation and that after a lag phase colonies are formed within the vegetation which reach the surface again at about 20 h.

Animals↗

PubMed1993

Microcirculatory patterns in adult rat cerebral hypophysis: a scanning electron microscope study of replicated specimens.

The blood vascular bed of the cerebral hypophysis in the adult rat was replicated completely or incompletely by arterial injection of different amounts of methacrylate resin, to be observed with a scanning electron microscope. Complete replication confirmed our previous findings (Murakami et al., 1987) on the distribution and structure of the vascular beds in and around the hypophysis of the rat. One long major and several minor portal routes (vide infra) were reproduced sufficiently together with the systemic veins of the posterior lobe. Incomplete replication demonstrated that resin flows: 1) via the long portal vessels from the median eminence and neural stalk to the anterior lobe; 2) via the accessory long portal vessels from the subependyma to the anterior lobe; 3) via the short portal vessels from the posterior lobe to the anterior lobe; 4) via the neuro-intermedial portal vessels from the posterior lobe to the intermediate lobe; 5) via the intermedio-distal portal vessels from the intermediate lobe to the anterior lobe; and 6) via the tuberal portal vessels from the tuberal lobe to the anterior lobe. Incomplete replication also demonstrated that resin in the median eminence and neural stalk is drained preferentially into the anterior lobe via the long portal vessels, and that resin in the posterior lobe is drained mainly into the systemic veins. We were unable to demonstrate a retrograde resin flow from the anterior lobe to the median eminence, subependyma, neural stalk, intermediate lobe and posterior lobe, nor an ascending resin flow from the posterior lobe to the median eminence and subependyma. Also failing to be noted were an ascending resin flow from the hypophysis to the hypothalamus and a descending resin flow from hypothalamus to the hypophysis.

Animals↗

PubMed1989

[Scanning electron microscopic studies of the para-odontoblast region of juvenile permanent teeth].

40 erupted premolar teeth from 9-14 year old patients requiring orthodontic treatment, were prepared for a study of the dentin-predentin-pulpal area with the scanning electron microscope. The odontoblast process has been found in all specimen extending through the predentin, inner dentin and middle layer of dentin. In the coronal pulp the odontoblast cell bodies were arranged closely together with granulated surfaces, surrounded by fibrillar structures and membrane junctions. As a rule a lot of spherical aggregates of crystals were present between the odontoblasts and the predentin surface.

Adolescent↗

PubMed2000

The pulvillus and empodium in Culex quinquefasciatus: visualization with the light microscope and a study of fine structure with the scanning electron microscope.

The empodia and pulvilli on each postarsus were examined in male and female Culex quinquefasciatus. Up to 160x magnification was required to see them clearly under the stereo light microscope but they were more readily visible under the compound light microscope as slide mounts at 100-200x magnification. Scanning electron micrographs of female and male pulvilli showed that they are either well developed (females) or inconspicuous (males) and that they consist of setal tufts composed of both pointed and trumpet-ended setae. The ultrastructure of the pulvilli is described and their possible function in oviposition is discussed.

Animals↗

PubMed1986

A scanning electron microscope study of the effect of etching time and mechanical pre-treatment on the pattern of acid etching on the enamel of primary teeth.

Eighty-five deciduous teeth, divided into five groups, were examined using a scanning electron microscope. The first two groups were etched for 60 and 120 sec respectively; the third and fourth groups were lightly milled and then etched for 60 and 120 sec respectively. In the first two groups, etching produced very few histological modifications. In the milled groups removal of the prismless enamel exposed the prisms to dissolution by the phosphoric acid. It was found that pretreatment and an etching time of 120 sec produced a constant and regularly distributed loss of inter- and intraprismatic substances.

Acid Etching, Dental↗