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Results for “scanning electron microscope”

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PubMed1992

Scanning electron microscopic and light microscopic observations on morphological changes of freeze-dried bone implantation in rats: comparison with fresh autogenous bone transplantation.

Bone remodelling after the implantation of freeze-dried autogenous bone in rat parietal bone was compared with fresh autogenous bone transplantation, using a scanning electron and light microscope revealed the time intervals after transplantation/implantation. The light microscope revealed the time delay of the bone remodelling in the implantation, compared with the transplantations. The scanning electron microscope showed that the differences between the two groups were in the states of bone union and bone resorption. In the fresh bone group, the newly-formed bone filled the spaces between host and the transplanted bones at 2 to 3 weeks after the transplantation: the newly-formed bone fused and melted into the transplanted bone. New bone formation was more dominant on the bone surface in the dura mater side than in the skin side. The union was almost completed at 5 weeks. In freeze-dried bone implantation, the bone union in the contact space was very poor and the implanted bone was mainly covered by the new bone, which developed from the host bone surface in the dura mater side at 2 to 3 weeks after the implantation. What is noteworthy is that bone resorbed areas showing numerous Howship's lacunae were mainly observed on the host bone surface in the vicinity of newly-formed bone. However in freeze-dried bone implantation, the bone resorption was greater on the host and implanted bone surface than that of fresh bone transplantation: the resorption of host bone was considerably larger at certain periods after freeze-dried bone implantation. The present results show that the healing process of freeze-dried bone implantation, even though autogenous bone was used, differed from that of fresh autogenous bone transplantation, and the differences are concerned not only with time sequences but also with qualitative changes. This suggests that the host would have some different responses to the freeze-dried autogenous bone from fresh materials.

Animals↗

PubMed1975

[Experimental investigations on cell resorption from the peritoneal cavity by use of the scanning electron microscope (author's transl)].

1. It is well known that microscopically small particles may be absorbed from the peritoneal cavity via the large lymphatic vessels. The present experiments were carried out in order to elucidate the site of the absorption. In addition, the role of transperitoneal transport of neoplastic cells as a possible cause of cancer metastases was studied. 2. The peritoneal surface of 40 rats and mice was studied with the scanning electron microscope (diaphragm, lateral abdominal wall). The investigations were carried out in 8 rats and 3 mice 24 hrs following the intraperitoneal injection of washed homologous erythrocytes and in 20 rats and 5 mice 24 hrs after the intraperitoneal injection of Ehrlich ascites tumor cells. 2 rats and 2 mice served as controls. 3. In the control animals no stomata could be shown in the peritoneum of the diaphragm or in the lateral abdominal wall. 4. The i.p. injection of erythrocytes was followed by the appearance of stomata in the peritoneal surface of the diaphragm, and absorption of erythrocytes could be demonstrated. No stomata were found in the peritoneum of the lateral abdominal wall. 5. Tumor cells were found in the stomata following the i.p. injection of ascites tumor cells. It is concluded that a lympho-hematogenous spread of tumor cells seems probable at least in the early stage of tumor infiltration of the peritoneum. This stage is followed by implantation of the tumor cells on the peritoneum.

Absorption↗

PubMed2004

Surface debris of canal walls after post space preparation in endodontically treated teeth: a scanning electron microscopic study.

PURPOSE: To evaluate surface cleanliness of root canal walls along post space after endodontic treatment using 2 different irrigant regimens, obturation techniques, and post space preparation for adhesive bonding. STUDY DESIGN: Forty teeth, divided into 4 groups, were instrumented, using Ni-Ti rotary files, irrigated with NaOCl or NaOCl+EDTA and obturated with cold lateral condensation (CLC) or warm vertical condensation (WVC) of gutta-percha. After post space preparation, etching, and washing procedure, canal walls were observed using a scanning electron microscope (SEM). Amount of debris, smear layer, sealer/gutta-percha remnants, and visibility of open tubules were rated. RESULTS: Higher amounts of rough debris, large sealer/gutta-percha remnants, thick smear layer, and no visibility of tubule orifices were recorded in all the groups at apical level of post space. At middle and coronal levels areas of clean dentin, alternating with areas covered by thin smear layer, smaller debris, gutta-percha remnants, and orifices of tubules partially or totally occluded by plugs were frequently observed. CONCLUSIONS: After endodontic treatment, obturation, and post space preparation SEM analysis of canal walls along post space shows large areas (covered by smear layer, debris, and sealer/gutta-percha remnants) not available for adhesive bonding and resin cementation of fiber posts.

Acid Etching, Dental↗

PubMed1981

A scanning electron microscopic study of the developing epithelial scleral papillae in the eye of the embryonic chick.

Eyes of early embryonic chicks possess 14 scleral papillae, derived from the conjunctival epithelium and present as transient structures between seven and 11 days of incubation. These papillae induce the formation of the 14 scleral ossicles, which develop in the adjacent, neural crest-derived ectomesenchyme. Each papilla undergoes a predictable series of developmental changes, divided by Murray ('43) into six morphological stages (M stages 1-6). We have confirmed his staging, and provide a scanning electron microscopic (SEM) evaluation of papilla development. The earliest stage that can be visualized with the S.E.M. is M stage 2. We describe the initial modifications of the surface of papilla cells, the presence of large microvilli and the asymmetrical morphogenesis and growth of the papillae. Papillae are shed by a mechanism that involves elongation of the cells at the base of the papilla. Such moribund papillae consist of necrotic cells coated with fibers.

Animals↗

PubMed2004

The application of a variable-pressure scanning electron microscope with energy dispersive X-ray microanalyser to the diagnosis of electrocution: a case report.

We describe here a case of accidental electrocution. A 48-year-old male was found dead in his room. At autopsy, there was a current mark on the right thumb and big toe. Histological examination revealed that the skin wound had the characteristics of a current mark, including vacuolation and elongation of the cell nuclei. We could also identify titanium metallization on the skin surface of the current mark using a variable-pressure scanning electron microscope (VP-SEM) equipped with energy dispersive X-ray microanalyser (EDX). The autopsy finding and the subsequent investigation support the conclusion that the cause of his death was electrocution. Our result shows that the VP-SEM with EDX is a useful tool for the forensic diagnosis of electrocution.

Accidents, Home↗

PubMed1993

Application of corrosion cast method for scanning electron microscopic observation of mouse embryo vasculature.

We described a method for making vascular corrosion casts of mouse embryos and applied it to study the vasculature of the whole body mouse embryo at 13.5 days (body length 9-11 mm) to 18.5 days (body length 18-23 mm), as well as that of its respective organs. The Mercox resin was perfused via the umbilical vessels using a special needle made by pulling the hematocrit tube (caliber 100-200 microns). The specimens were treated with 10% NaOH, rinsed, dried, coated with gold and observed under a scanning electron microscope. Visceral organs of a 13.5 day embryo were rather immature, but the liver vasculature was relatively well developed. In a 15.5 day embryo, the whole body vasculature was relatively well developed and the features of respective organs could be identified. In a 18.5 day embryo, almost all organs and extremities were well developed, but sensory organs in some parts showed immature development.

Animals↗

PubMed1984

Effect of various root surface treatments on the attachment and growth of human gingival fibroblasts: histologic and scanning electron microscopic evaluation.

Human teeth extracted because of advanced periodontal disease were obtained. The portions of the roots which had been exposed in periodontal pockets were either untreated or were treated with root planing or citric acid, or root planing followed by citric acid. Human gingival fibroblasts were then added to the roots so treated and were allowed to incubate for 72 h. The ability of cells to attach to and grow onto these roots was assessed by means of gross evaluation of staining intensity and by histologic and scanning electron microscopic observation. The results of multiple experiments in each root-treatment category indicated that only roots which had been planed, whether or not citric acid demineralization was used, promoted cell attachment and growth. In addition, there were no discernible morphologic differences in the cells which were plated onto roots which were root planed only, compared to those which were root planed and citric-acid treated. In both situations too, the cells displayed morphology typical of human gingival fibroblasts in culture.

Cell Adhesion↗

PubMed1976

Thrombus formation around an endocardial pacemaker electrode: a scanning electron microscopic study and its relationship to abnormal threshold elevation.

The author experienced an abnormal increase in stimulation threshold in one patient to whom a permanent endocardial electrode was implanted according to the temporary-permanent technique, but could safely exchange the electrode at the fifth postoperative day before exit block would have occurred. Around the extracted electrode there was a thrombus which was considered to be the main causative factor of abnormally increased stimulation threshold. The morphology of the surface of the thrombus and surface of the electrode was examined using a scanning electron microscope, and the author found that the membranous thrombus which surrounded the neck of the lead had a very fine network of configuration with multilayers and that, though macroscopically the electrode tip was clean and the metal was brilliant, there were scattered white masses strongly adhered to the surface of it. Thus in a case of rapid increase of stimulation threshold within a few days after implantation, it is advisable to withdraw the catheter and to implant another new one.

Aged↗

PubMed1986

Scanning electron microscope and electron microprobe study of reactions of stannous fluoride and stannous chloride with dental enamel.

Stannous fluoride but not stannous chloride has shown a caries inhibiting effect in animal studies. The effect of aqueous solutions of stannous fluoride and stannous chloride on dental enamel surfaces was investigated by scanning electron microscope and analytical electron microprobe. Some large globules and a continuous layer of small globules were observed after stannous fluoride treatment. The large globules were soluble in both water and alkali, whereas the small ones were only soluble in alkali. Both fluoride and tin were found to be present on the enamel surfaces by the electron microprobe after stannous fluoride treatment. The fluoride could not be detected after immersion in distilled water whereas alkali treatment removed the tin. The large fluoride-containing globules may consist of calcium fluoride as this substance is known to be slightly soluble in water and soluble in alkali. Stannous chloride treatment gave a layer of small tin-containing globules with properties similar to the layer formed on enamel treated with stannous fluoride. It is therefore suggested that the tin-containing layer is not associated with caries protection whereas calcium fluoride-like deposition on the enamel probably is a factor in the caries inhibition caused by stannous fluoride.

Dental Enamel↗

PubMed1995

Scanning electron microscopic studies of reticular framework in the rat mesenteric lymph node.

BACKGROUND: The reticular framework in the lymph node has in the past been studied mainly by light microscopy of silver-impregnated specimens. The aim of the present study is to understand three-dimensionally the ultrastructure and organization of the reticular framework better than before. METHODS: The mesenteric lymph nodes of the rat were prepared either an alkali-water maceration method or a conventional method and were observed in a scanning electron microscope (SEM). RESULTS: The SEM study of alkali-water macerated tissues visualized directly the reticular fiber network in the lymph node. The reticular fibers consisted of thin bundles of collagen fibrils. They were continuous with the collagen fibrillar sheaths of blood vessels and lymphatic sinuses as well as with the fibrous capusule, thus acting as a skeleton of the lymph node. The arrangement of the reticulum was variable, depending on individual compartments. The SEM study of conventionally treated tissues, on the other hand, clarified the shape of reticular cells and their relationship with the reticular fibers. The sinus reticular cells connected with the sinus lining cells but separated from the parenchymal reticular cells, indicating that the former two originate from lymphatic endothelial cells. The parenchymal reticular cells varied in shape depending on their locations but essentially shared features with fibroblasts. CONCLUSIONS: The arrangements of the reticular fibers in the parenchyma were closely related to the associated reticular cells, showing the possibility that the reticular cells maintain the shape of the reticular framework suitable for each compartment of the lymph node.

Animals↗

PubMed1987

Simultaneous visualization of myeloperoxidase reactivity and immunogold labeling by backscattered electron imaging with the scanning electron microscope.

We describe a method to label circulating human granulocytes with an immunogold marker and then incubate them for demonstration of myeloperoxidase activity. The cells were observed in the backscattered electron imaging (BEI) mode of the scanning electron microscope. This permits simultaneous visualization of cell surface morphology, the immunological surface marker, and the cytochemical reactivity of each individual cell. Enhanced identification of the various cell types and more precise characterization of cell surface features in the different steps of leukocyte differentiation are expected to result from application of this technique.

Gold↗

PubMed1999

Human teeth with periapical pathosis after overinstrumentation and overfilling of the root canals: a scanning electron microscopic study.

AIM: The aim of this study was to determine whether overinstrumentation followed by immediate overfilling could be a potential risk in the treatment of infected root canals. METHODOLOGY: Thirty-five human teeth with infected root canals were overinstrumented and overfilled approximately 45 min after their extraction. The experimental teeth were enlarged up to size 40 and the overinstrumentation and overfilling were checked with the aid of a magnifying glass. The specimens were fixed in glutaraldehyde plus sodium cacodylate solution and prepared for scanning electron microscope examination. RESULTS: Bacteria were detected on the flute of the files and mostly at the root apices around the main foramen, remaining firmly attached to resorptive lacunae despite the fact that the apices had undergone great changes, including fracture or zipping. A control group consisting of 10 human teeth root canals containing vital pulps were also overinstrumented and overfilled. No bacteria were detected on the flutes of the files, at the apices or on the extruded master cone overfilling these samples. CONCLUSIONS: The high percentage of bacteria adhering to the resorptive lacunae or in the flutes of files used in overinstrumented human teeth with infected root canals carry a potential risk for postoperative pain, clinical discomfort and flare-ups. The hazards observed in these circumstances do not support the one-visit treatment of teeth having acute or chronic periapical abscesses.

Bacteria↗

PubMed1991

[Scanning electron microscopic observation of the collagen fibrillar network in Bruch's membrane by cell maceration].

Cellular elements, including retinal pigment epithelia, were removed by the cell maceration method to obtain a three-dimensional view of the collagen fibrillar networks of Bruch's membrane. A bird's eye view of the inner collagenous zone of Bruch's membrane was obtained using the eyes of albino rabbits and Japanese monkeys. The eyes were treated with a low concentration of NaOH for several days and then observed with a scanning electron microscope. This procedure allowed the exposed inner collagenous zone of Bruch's membrane to be observed. In addition, the outer collagenous zone was also be observed in some of the specimens. Both zones were formed by dense lattices of fine collagen fibrils, and these fibrils frequently formed bundles in the outer collagenous zone. In the posterior poles of the eyes obtained from Japanese monkeys, a network of wavy fine collagen fibrils was observed. In both outer and inner collagenous zones, most of the collagen fibrils ran parallel to the retina. Fenestration of the sheet-like elastic layer was frequently observed through gaps in the thin collagen fibrillar network of the inner collagenous zone. The method employed in this study was considered suitable to obtain a wide bird's eye view of the collagenous zone of Bruch's membrane.

Animals↗

PubMed1986

Eyelid development and fusion induced by cortisone treatment in mutant, lidgap-Miller, foetal mice. A scanning electron microscope study.

In normal mice the eyelids grow across the eye and fuse together during days 15 and 16 of gestation, and the mice are born with their eyes closed. In mutant lgMl)/lgMl) (lidgap-Miller) foetuses this growth and fusion does not occur and the mice are born with their eyes open. A single prenatal treatment with cortisone on day 14 of gestation masks the genetic defect, and the mice are born with their eyes closed. In the present study, a scanning electron microscope was used to investigate: whether eyelid closure in cortisone-treated lgMl/lgMl foetuses differs from that in normal foetuses of the CBA/J and ICR/Ml strains and, if so, how; and off developing eyelids of untreated lgMl/lgMl foetuses differ from normal. The induced closure differs from normal. During their growth, eyelids of treated mutant foetuses have a deficiency of rounded periderm cells at their margins; the margin cells agglomerate and flatten prematurely. In closed eyes of treated mutants there is a gap between periderm cells of the upper and lower eyelids along part of the fusion line. Fusion is completed late, during day 17. Maturation of the head periderm is advanced in treated lgMl/lgMl foetuses on day 16, relative to normal CBA/J and untreated lgMl/lgMl foetuses. Untreated lgMl/lgMl foetuses differ from normal in that the eyelids never cover the eye and lack rounded periderm cells at their perimeter. The periderm cells present form a flattened band along the eyelid margin rather than, as in normal eyelids, along the fusion line. The results of the cortisone study suggest that the route to eyelid closure in mice may not be narrowly canalized either in cell morphology or number, or in timing, and that closed eyes may be achieved after cortisone treatment in lgMl/lgMl foetuses as part of an induced maturation of the periderm.

Animals↗

PubMed2002

Thrombus formation on guide wires during routine PTCA procedures: a scanning electron microscopic evaluation.

BACKGROUND: Various coatings are used on catheters and guide wires to improve resistance to surface thrombus formation. However, little is known about the thrombogenicity of 0.014" angioplasty guide wires and the protection offered by these coatings. OBJECTIVES: To evaluate the thrombogenicity of five different guide wires used in coronary angioplasty. METHODS: Five different 0.014" guide wire types were evaluated in 50 consecutive angioplasty procedures. At the end of the procedure, the distal part of the guide wire was cut, put in formalin and prepared for scanning electron microscopic evaluation. The condition of each guide wire was then classified into one of three predefined categories: no thrombus, limited thrombus and significant thrombus formation. RESULTS: Silicone (n=10, Guidant, USA), phosphorylcholine polymer (n=8, Biocompatibles, Ireland), hydrophilic polymer (n=8, Scimed, USA) and two Teflon-based coatings (n=16, Schneider, USA; n=8, Cordis, USA) were evaluated. On microscopic examination, 48% of guide wires had a significant amount of thrombus, 18% had limited thrombus formation and 34% had no thrombus. The results were very dissimilar among the groups. Significant thrombus was found on 80% of Guidant guide wires, 69% of Schneider guide wires, 38% of Scimed guide wires and 25% of Cordis guide wires, while none was found on Biocompatibles guide wires (P<0.0001). CONCLUSIONS: Significant thrombus formation on angioplasty guide wires was a frequent finding, occurring in 48% of cases. Resistance to thrombus formation was very dissimilar among coatings, with only the Biocompatibles phosphorylcholine-coated guide wires showing no thrombus formation at all. Whether subclinical thromboembolization occurred in some patients is unknown, and the clinical implications of this study remain to be defined.

Aged↗

PubMed1984

Scanning electron microscopic and electron microprobe X-ray analysis of cortical bone of fluoride-treated rabbits.

Sodium fluoride was administered to rabbits through the intragastric route at the rate of 10 mg/kg every day for a period of 8 months. Cortical bone from the diphyseal region of the femur was studied morphologically with a scanning electron microscope, and significant structural changes in collagen fiber were observed in the fluoride-treated animals as compared to normal bone. Similar bone samples were assessed physically for their CaK alpha/PK alpha ratio by electron microprobe x-ray analysis, and chemically for their calcium and phosphorus content. The bone from the rabbits to which sodium fluoride had been administered showed a higher Ca/P ratio than that from untreated control animals by both of the methods of assessment. Possible explanations for the increased Ca/P ratio in relation to the observed structural changes are discussed.

Animals↗

PubMed1995

Dentin wall adaptation of multiphase versus temperature thermoplasticized gutta-percha. A scanning electron microscopic study.

An in-vitro study was designed to compare dentin wall adaptation of Multiphase gutta-percha root canal obturation technique versus high temperature thermoplasticized gutta-percha (Obtura) in the presence and absence of smear layer. Forty single rooted teeth with straight canals were used. After decapitation roots were divided into two equal groups. Group (I) received final irrigation with EDTA and Sodium hypochlorite (NaOCI) to remove the smear layer, while roots in Group (II) were irrigated with NaOCI alone. Each group was then subdivided into two subgroups to represent the two filling techniques. Teeth were sectioned longitudinally and viewed under scanning electron microscope. Multiphase gutta-percha showed excellent adaptation to canal wall, specially in the absence of smear layer and displayed a homogeneous mass with little amount of voids than the Obtura system.

Dental Marginal Adaptation↗

PubMed1993

[Scanning electron microscopic study on inner ear barotrauma: in the guinea pig with one eustachian tube occluded].

In order to investigate the mechanism of inner ear barotrauma, guinea pigs, with one eustachian tube occluded, were subjected to compression and decompression between 1 absolute pressure and 2 absolute pressures in a high pressure chamber. The authors divided the animals into three groups according to the speed of compression and decompression. Each group contained 10 guinea pigs. Morphological changes in the cochlear sensory hairs were examined by means of scanning electron microscope. On the occluded side, hair cells were damaged more frequently and more severely by rapid compression than by rapid decompression. There was no difference in the degree of damage produced by slow decompression and rapid decompression. On the control side, slight or moderate damage to hair cells was observed mainly as a result of rapid decompression. These findings led us to hypothesize that, in the setting of normal eustachian tube function, inner ear barotrauma would generally be caused by the relative positive pressure in the middle ear cavity that occurs during decompression. Furthermore, animals deprived of eustachian tube function would not have sufficient endurance for rapid compression and would sustain inner ear barotrauma far more readily, and of far greater severity, with rapid compression than would animals with normal eustachian tube function. The difference may be due to the presence of another pressure transmission pathway to the inner ear. The mechanism of cochlear sensory hair damage due to atmospheric pressure changes is presumed to be distortion of the reticular lamina and cuticular plate caused by the difference in pressure between cortilymph (perilymph) and the subtectorial space (endolymph) resulting in injury to stereocilia.

Animals↗