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Results for “scanning electron microscope”

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At least 343 records · Page 19Linked to original sources

PubMed1989

Ultrastructural changes of the basilar artery following experimental subarachnoid haemorrhage. A morphological study on the pathogenesis of delayed cerebral vasospasm.

Recent experimental studies have shown, that the endothelium of cerebral vessels undergoes significant changes after subarachnoid haemorrhage which may lead to biochemical changes at the endothelial surface with disturbance of the delicate homeostasis of vasodilating and vasoconstricting mechanisms which are thought to be responsible for preservation of the tones of the cerebral vasculature. Ultrastructural studies incorporating different forms of microscopic observations of the endothelium after SAH representing a prerequisite for further investigations on the pathogenesis of cerebral vasospasm are scarce. The experimental study was performed in order to investigate and define more precisely the pathomorphological changes at the endothelial surface of the basilar artery of dogs after experimental SAH. Two separate injections of autologous blood into the cisterna magna within 72 hours resulted in extensive angiographic narrowing of the diameter of the basilar artery of all animals. Histological studies of the basilar artery including light microscopic, transmission electron microscopic, scanning electron microscopic and freeze cracking microscopic examinations demonstrated severe pathomorphological changes at the endothelial surface. These consisted mainly of infolding and corrugation of the endothelium, disorientation and desquamation of endothelial cells as well as of vacuolation and ingrowth of fibrous tissue between the endothelial and muscular layer. No pathomorphological changes could be observed in the muscular layer. As the described post-haemorrhagic ultrastructural changes of the endothelium cerebral vessels in spasm are likely to represent the morphological basis of the delayed form of cerebral vasospasm future research on its pathogenesis should primarily focus on the structural and biochemical taking place at the endothelial surface of the cerebral vasculature after SAH.

Animals↗

PubMed2005

[Periosteum construction in vitro by small intestinal submucosa combined with bone marrow mesenchymal stem cell].

OBJECTIVE: To investigate the practicability of periosteum construction in vitro by small intestinal submucosa (SIS) as a tissue scaffold with bone marrow mesenchymal stem cells (BMSC). METHODS: The bone marrow mesenchymal stem cells were cultivated by the conventional method in vitro, and then co-cultivated with SIS. The morphological feature of the complex material, the extracellular matrices, the adhesion and proliferation of BMSC were observed by optical microscope, electronic microscope, scanning electronic microscope and histologic evaluation respectively. RESULTS: BMSCs adhered and proliferated on SIS, secreted a great deal of extracellular matrices with active cellular function. BMSCs grew well there in layers, and the thickness became thicker as time passed, acting like a biological periosteum. CONCLUSION: Combined culture of SIS and BMSC in vitro can construct a tissue engineering periosteum similar to the natural one, thus providing a base for further study of its osteogenic regeneration in vivo.

Animals↗

PubMed1987

Scanning electron microscopic study of nocturnally subperiodic Brugia malayi (Filarioidea: Onchocercidae), Narathiwat, Southern Thailand.

Scanning Electron Microscopic (SEM) observations were made on the adult females and males of nocturnally subperiodic Brugia malayi (Narathiwat, Southern Thailand) from 8-month-old intra-peritoneally infected jirds (Meriones unguiculatus). Descriptions of the morphological surfaces of anterior end, vulva, body cuticle, anus, posterior end of females and anterior end, body cuticle, cloaca, caudal papillae, spicules, sheath, posterior end of males were demonstrated. The comparison among these and other filarial parasites were also investigated.

Animals↗

PubMed1982

Osteogenesis imperfecta lethal in infancy: case report and scanning electron microscopic studies of the deciduous teeth.

Radiologic evaluation of the skeleton and scanning electron microscopic studies of the teeth were performed on an infant boy with a lethal osteogenesis imperfecta (OI) syndrome who died at 10 mo of pneumonia. The skeletal findings included ribs that were focally expanded by fracture calluses, flat vertebral bodies, and wide limb bones. On fractured tooth surfaces, the enamel and dentin were normal as was the dentin calcification front. Although microscopic abnormalities have been noted in teeth from previously reported infants with lethal OI, a few studies also report infants with normal teeth. These differences in dental findings may indicate heterogeneity in OI lethal in infancy. Results of our study indicate that, until the primary biochemical defects in the OI syndromes are elucidated, examination of teeth from other infants with lethal OI and detailed evaluation of other clinical and skeletal features will aid in delineating heterogeneity and variation in expression in lethal OI.

Humans↗

PubMed1984

Scanning electron microscopic study of odontogenic keratocysts.

Three odontogenic keratocysts were examined with a scanning electron microscope (SEM) on their surface cells, prickle cells, basal cells, and the epithelial-connective tissue interface. The microridges of the surface cells had a short, discontinuous, branched or beaded appearance. Intracellularly, the flattened keratinized cells formed a network consisting of delicate microfilaments. The prickle cells had numerous cytoplasmic projections and a large round nucleus that occupied most of the cytoplasm. The basal cells had two types of cytoplasmic process and a large oval polarized nucleus. The epithelium and the lamina propria were connected by a fibrous and fibrillar network.

Adolescent↗

PubMed1979

[The human dental pulp as viewed through a scanning electron microscope (author's transl)].

The human dental pulp was examined using a scanning electron microscope. The odontoblasts are pear-shaped and have a fine-grain surface structure. Tomes' process divides into fine branches before entering the predentin. Very few fibroblasts were found. These had stronger cell processes at the two terminal poles. Adhering to their surfaces were fine fibers. Collagenous and nerve fibers could not be accurately identified in the rich fibrillary network of the pulp. Stronger nerve fasciculi were readily observable through longitudinal sulci. Thinner fibers were seen to spread out in branches from some nerve bundles. The capillaries were observed to be surrounded by a sheath of fine fibrils.

Capillaries↗

PubMed1976

Scanning electron microscope study of human veins and aorta-coronary artery vein grafts.

Scanning electron microscope study of two vein grafts which were removed after 50 months of implantation as aorta-coronary artery vein grafts showed considerable subendothelial thickening, which consisted of relatively cell-poor fibrous layer. In one of the grafts the endothelial surface was intact; the second graft showed focal loss of endothelial cells. Sections of two fresh human veins, studied prior to their insertion as aorta-coronary artery vein grafts, have shown that they retained an intact endothelial layer. A third fresh vein, however, showed focal damage with missing endothelial cells and adherent fibrin.

Autopsy↗

PubMed1977

A scanning electron microscopic survey of the brain ventricular system of the female armadillo.

The scanning electron microscope was used to survey the brain ventricular system of the female armadille (Dasypus novemcinctus) with emphasis on the third ventricle. The walls of the lateral ventricles, aqueduct, and fourth ventricle are covered by long cilia. In the lateral ventricle, the cilia are arranged in groups; but in the aqueduct and fourth ventricle, they are evenly placed over the cellular surfaces. The ependymal cells of the third ventricle are densely ciliated except for the organum vasculosum and infundibular recess. The non-ciliated luminal surface of these areas has a pebblestone appearance punctuated by numerous microvilli and two types of supraependymal cells.

Animals↗

PubMed1980

[Comparative scanning electron microscopical investigation of the bond between bone and different alloplastic implant materials (author's transl)].

The traditional alloplastic implant materials and their applications are represented and are investigated in a comparative scanning electron microscopical study between bone and alloplastic. Provable are clear in "bio-vitroceramic Ap 40" compounds to the bone in the scanning electron microscopical photo-contrary to titanium, tantalum and teflon.

Animals↗

PubMed1989

Scanning electron microscopic pattern of recurrent vaginitis by Candida albicans in the mouse.

The scanning electron microscopic pattern of the development of yeasts of Candida albicans on the vaginal mucosa of mice in oestral phase, was studied in four consecutive infections performed at 30 d intervals. The findings were practically identical following the 1st and 2nd infections, evidencing a progressive mycelial development starting from 12 to 72 h after inoculation with C. albicans yeasts. In the 3rd and 4th infections the mycelial tufts appeared extremely reduced in number and size, although there was an acceleration in the early evolutive phases and the filamentation process had already started 6 h after infection. It can be concluded that, after successive infections with C. albicans, mouse vaginal mucous membrane develops a local state of resistance evidenced by the decrease in mycelial tufts. The possible causes of the early onset of the filamentation process are discussed.

Animals↗

PubMed1979

A preliminary study of scanning electron microscopic changes of the duodenum during healing of duodenal ulcers.

Using the scanning electron microscope, changes in the rat duodenum have been studied during the healing of gastric secretagogue-induced duodenal ulcers on the 1st, 3rd, 7th and 10th days post-infustion. A montage technique with fine resolution has allowed both the entire area of the duodenum and the cellular organization in individual villi in proximity to the ulcers to be investigated. There was a considerable range of appearances noted at any one time point due to the variations in the size and depth of the original area of ulceration. On day 1, there was acute destruction of the mucosal surface with distortion of the villi at the ulcer margin. By the 3rd day, some specimens already showed full epithelialization over the defects whereas others up to day 10 revealed persistent areas of ulceration. Occasional specimens showed areas suggestive of gastric surface metaplasia on the villous surface adjacent to these ulcers.

Animals↗

PubMed1990

Immunogold labelling of membrane receptors for scanning electron microscopical investigations of genetically determined disorders of lipid metabolism.

Receptors binding of low-density lipoprotein at surfaces of human lymphocytes was studied by immunochemical and scanning electron microscopical methods. Using colloidal gold sol binding ability of cells from several probands could be demonstrated by immunolabelling. We investigated cell material from normolipidaemic persons and from patients with heterozygote autosomal monogenic hypercholesterolaemia. We found a distinct decrease of labelled gold particles at the cell surface of patients with this disorder of lipid metabolism. The simple extraction possibility of lymphocytes from human venous blood and the demonstrated scanning electron microscopical results recommend the described procedure for genetic application.

Apolipoproteins↗

PubMed1981

Comparative scanning electron microscopic investigations of the sensory epithelia in the teleost sacculus and lagena.

Scanning electron microscopic studies were conducted on the sensory epithelia of the auditory portions of the ears in teleost species representing wide taxonomic diversity. A number of the features of the ears investigated resembled features found in other teleost species, although some major exceptions to earlier patterns were found, particularly in the saccular sensory epithelium. The saccular maculae of all but one species contained basically similar ciliary bundles on the sensory hair cells while there was some significant variation on the lagenar maculae. Hair cell orientation patterns on the sacculus contained four orientation groups in all of the species, other than the mormyrid, Gnathonemus, which only had two groups. Lagenar maculae had two orientation groups, and the orientation patterns were similar to one another. The most divergent form of lagenar macula was found in gnathonemus. These data, combined with data from earlier investigations, provide a broad overview of the surface features of the ear in teleost fishes. Most significantly, it now appears that there are at least five different saccular hair cell orientation patterns among teleost fishes, and all of these patterns are found spread through many major teleost taxa. While there is some similarity in ear structures among some groups of closely related species, such as the Elopomorpha and the Gadiformes, it is becoming more apparent that there is extensive convergence in a number of features of he teleost ear that most likely reflect similar selective pressures during the evolution of the ear. The nature of these selective pressures, however, are not well understood.

Acoustic Maculae↗

PubMedDate not supplied

Light and scanning electron microscopic report of four fractured implants.

Although they are fortunately rare, implant fractures can cause significant problems for both clinicians and patients. The authors present a light and scanning electron microscopic study of four fractured implants in two patients. Both patients had parafunctional habits (bruxism), hypertrophic masticatory muscles, and wear of occlusal surfaces. The scanning electron microscopic study of the fractured surfaces of all four implants showed the presence of fatigue striations. Bending overload was probably created by a combination of parafunctional forces, bone resorption, posterior location of the implants, and implant diameter.

Aged↗

PubMedDate not supplied

A spectroscopic scanning electron microscope design.

This paper describes a proposal to improve the design of scanning electron microscopes (SEMs). The design is based upon using an SEM column similar to the conventional one, magnetic sector plates and a mixed field immersion objective lens. The optical axis of the SEM column lies in the horizontal direction and the primary beam is turned through 90 degrees before it reaches the specimen. This arrangement allows for the efficient collection, detection and spectral analysis of the scattered electrons on a hemispherical surface that is located well away from the rest of the SEM column. The proposed SEM design can also be easily extended to incorporate time multiplexed columns and multi-column arrays.

Journal Article↗

PubMed2004

The effect of beam diameter on the electron skirt in a high pressure scanning electron microscope.

Helium gas and air are commonly used in the high pressure scanning electron microscope (HPSEM). The presence of a gaseous environment in the specimen chamber modifies the electron beam profile. In order to fully understand the beam-gas interaction, we have investigated the beam-diameter effect for two gases (helium and air) by Monte Carlo simulation. In this calculation, we have assumed that the electron beam is Gaussian and we have explored the influence of the nature of the gas at low voltage. When the beam diameter varies between 1 and 100 nm, there is no influence on the beam profile for these two gases. The resolving power of the HPSEM is not affected by the beam-gas interaction. These theoretical results have been compared with experimental images obtained at low voltage under air and helium gases. The variation of image quality at low voltage has confirmed the interest of helium for use in a Field Emission Gun SEM (FEGSEM) in high pressure (or low vacuum) conditions.

Journal Article↗

PubMed2005

[Scanning electron microscopic observations of Monochamus alternatus antennal sensilla and their electroantennographic responses].

With scanning electron microscope (SEM), this paper observed the shape, category, amount and distribution of the main antenna sensilla of adult Monochamus alternatus, and tested their electroantennographic (EAG) responses to the main volatiles of Pinus spp.. There were seven types of antennal sensilla, i. e., sensilla trichoid, sensilla basiconica, sensilla digit-like, sensilla rod-like, sensilla bottle-like, sensilla bud-like and sensilla chaetica, among which, sensilla trichoid and sensilla basiconica were the most abundant on the antenna surface, and each of them could be divided into three subtypes. Two subtypes of sensilla digit-like could also be observed. The II and III subtypes of sensilla trichoid and I and II subtypes of sensilla basiconica had deep longitudinal grooves on their surface, the typical characteristics of olfactory receptor. The comparison of the EAG response of different parts of Monochamus alternatus antennae to alpha-Pinene showed that each volatile and their compounds could provoke significant EAG responses of both females and males. The dose-response test showed that there was a certain rule in the EAG responses of M. alternatus.

Animals↗

PubMed1975

A scanning electron microscopic study of 34 cases of acute granulocytic, myelomonocytic, monoblastic and histiocytic leukemia.

This report describes the surface architecture of leukemic cells, as seen by scanning electron microscopy in 34 patients with acute nonlymphoblastic leukemia. Six patients with myeloblastic, 4 with promyelocytic, 10 with myelomonocytic, 8 with monocytic, 4 with histiocytic and 2 with undifferentiated leukemia were studied. Under the scanning electron microscope most leukemia histiocytes and monocytes appeared similar and were characterized by the presence of large, well developed broad-based ruffled membranes or prominent raised ridge-like profiles, resembling ithis respect normal monocytes. Most cells from patients with acute promyelocytic or myeloblastic leukemia exhibited narrower ridge-like profiles whereas some showed ruffles or microvilli. Patients with myelomonocytic leukemia showed mixed populations of cells with ridge-like profiles and ruffled membranes whereas cells from two patients with undifferentiated leukemia had smooth surfaces, similar to those encountered in cells from patients with acute lymphoblastic leukemia. It appears that nonlymphoblastic and lymphoblastic leukemia cells (particularly histiocytes and monocytes) can frequently be distinquished on the basis of their surface architecture. The surface features of leukemic histiocytes and monocytes are similar, suggesting that they may belong to the same cell series. The monocytes seem to have characteristic surface features recognizable with the scanning electron microscope and differ from most cells from patients with acute granulocytic leukemia. Although overlap of surface features and misidentification can occur, scanning electron microscopy is a useful adjunct to other modes of microscopy in the study and diagnosis of acute leukemia.

Acute Disease↗