SEARCH · PubMed Health

Results for “scanning electron microscope”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources

PubMed1975

A robust micromanipulator for the scanning electron microscope.

A simple device for holding and moving mechanical tools in the region of a sample being viewed in the scanning electron microscope is described. The unit has a 20:1 mechanical reduction and when fitted with a tungsten carbide dental chisel, it is sufficiently rigid to cut biological hard tissues. Alternately, when fitted with an electro-etched tungsten needle, it can be used, in conjunction with specimen stage controls, to remove individual cells from the surface of soft tissues. Examples of these applications are illustrated.

Animals↗

PubMedDate not supplied

Scanning electron microscopic study: the effect of balanced salt solution on rabbit corneal endothelium.

A serial study was carried out with the scanning electron microscope every 5 h to examine the endothelial alterations that occur when the rabbit cornea remains in the eye after enucleation. The findings are compared with those encountered when the cornea with a scleral rim was removed from the globe immediately after enucleation, immersed in Balanced Salt Solution, and observed at the same time intervals. Our results indicate that this procedure protects the corneal endothelium for at least 20 h.

Animals↗

PubMed1985

Scanning electron microscopic observations on the inner surface of jaw cysts.

The cavity surface of 9 jaw cysts was studied in the scanning electron microscope. The material comprised 5 radicular, 2 residual, 1 dentigerous and 1 globulomaxillary cyst. The surface morphology varied from smooth to ruffled within the same cyst, and between cysts. Interepithelial spaces, some of which contained migrating leukocytes, were frequently observed. Bacteria occurred in 1 cyst (dentigerous) only, and included rods, filaments and spirochetes. Crystals of various morphology were seen in 6 of the cysts.

Adolescent↗

PubMed1977

Scanning electron microscopical examination of gonococcal urethral exudate.

The relationship of gonococci and phagocytes in gonococcal urethral exudate was examined using a scanning electron microscope. Several stages in the phagocytic process were evident. These included pseudopodias, microvilli, and simple attachment of gonococci to phagocytic surfaces. Epithelial cells, also a part of the exudate, were examined in this study. Parallels are drawn between this and other phagocytic systems. The technique provides excellent preservation of phagocyte-bacterial interrelationships and offers a means of investigating the nature of the resistance of Neisseria gonorrhoeae to phagocytosis.

Exudates and Transudates↗

PubMedDate not supplied

Corrections of magnification and focusing in a cathode lens-equipped scanning electron microscope.

One of the well-proven and efficient methods of obtaining a very low-energy impact of primary electrons in the scanning electron microscope is to introduce a retarding field element below the pole piece of the objective lens (OL). It is advantageous to use the specimen alone as the negatively biased electrode (i.e., cathode of the cathode lens). The optical power of the cathode lens modifies some of the standard parameters of the image formation such as relation of working distance to OL excitation or magnification to the scanning coils current, the impact angle of primary electrons, and so forth. In computer-controlled electron microscopes these parameters, particularly with regard to focusing and magnification, can be corrected automatically. Derivation of algorithms for such corrections and their experimental verifications are presented in this paper. Furthermore, a more accurate analytical expression for the focal length of an aperture lens is derived.

Journal Article↗

PubMed1976

Double afferent arterioles of the rat renal glomerulus as studied by the injection replica scanning electron microscopic method.

One thousand eight hundred and fifty-six specimens of replicated rat renal glomerulus were examined under the scanning electron microscope, and an extremely rare anomaly of the glomerulus with double afferent arterioles was described. The double afferent arterioles arose separately from a terminal twig of the interlobular artery and reached the vascular pole of a subcapsular glomerulus which possessed a single efferent arteriole. Microdissection revealed that this glomerulus was composed of three fairly independent lobules of anastomosing capillaries. Microdissection also revealed that the double afferent arterioles were isolated from each other even in the glomerulus: the one supplied two lobules, while the other the third one only.

Animals↗

PubMed1998

Bovine cumulus-corona cells in maturing oocytes. A scanning electron microscopic study.

The ultrastructural features of cumulus-corona cells surrounding maturing oocytes in bovine were studied by means of scanning electron microscope in order to provide a detailed description of their surface changes during oocyte maturation. Cumulus corona cell complexes of immature oocytes showed a compact aspect with narrow intercellular spaces. The spaces around mature oocytes enlarged because they were progressively filled with abundant microfibrillar extracellular matrix. In cumulus corona cells complexes of immature oocytes very numerous long and filiform microvilli were observed, whereas the cumulus corona cell surface surrounding mature oocytes showed occasional large cytoplasmic protrusions along with scanty microvilli and numerous blebs.

Animals↗

PubMed1979

Pores of the palatine tonsillar crypt and pharyngeal tonsillar recess--a scanning electron microscopic study--.

The crypt of the palatine tonsil and the recess of the human pharyngeal tonsil were studied using a scanning electron microscope. Many pores, ranging in diameter from 10 to 100 microns, were observed on the luminal surface of the crypts. All of the crypt surface except at the sites of pores was covered by epithelial cells. Non-epithelial round cells, mostly lymphocytes, were exposed directly to the crypt lumen through these pores. In the lumen of palatine tonsillar crypts, numerous round cells were present which evidently pass through these pores from the parenchyma. This finding indicates that the tonsillar parenchyma is directly open to the crypt. Similar findings were obtained in the recess of the pharyngeal tonsil.

Child↗

PubMed1983

Studies on the arrangement of the collagenous fibers in infant epiphyseal plates using polarized light and the scanning electron microscope.

The architecture of the collagenous fibers in epiphyseal plates of infantile long bones was investigated using polarized light and scanning electron microscope. In the zone of columnar cartilage the collagenous fiber bundles are arranged longitudinally in the intercolumnar cartilaginous septa. In addition to this main longitudinal orientation, some of the fibers branch off at an acute angle and flow through the cartilage columns surrounding rhombus-shaped groups of chondrocytes. In the area adjaced to the inert cartilage the collagen fibers become curved and form a network of arcades. In the zone of inert cartilage the collagenous fibers are arranged in a honeycomb-like fashion. The importance of the arrangement of the collagen fibers to the loading strength of the epiphyseal plate is discussed.

Age Factors↗

PubMed1981

Evaluation of low-viscosity intravascular silicone rubber with scanning electron microscope.

A low-viscosity silicone rubber polymer used as an intravascular embolization material was studied with the aid of a scanning electron microscope. The silicone polymer became permanently affixed to the vessel endothelium without observable morphologic changes in the endothelium. No evidence of late recanalization of the embolized vessels was found in our experimental sections.

Animals↗

PubMed1984

The surface structural alterations of elastic fibers and elastotic material in solar elastosis: a scanning electron microscopic study.

The surface structure of altered elastic fibers and elastotic material in solar elastosis has been described using a scanning electron microscope. There were 3 different areas in the dermis, depending on the degree of changes in elastic fibers: areas of (1) normal-looking fibers, (2) thick, cylindrical fibers, and (3) a large mass of markedly changed fibers. They were mainly located in the deep, middle, and upper dermis, respectively. The normal-looking fibers were the same as the normal elastic fiber. The thick, cylindrical fibers showed various findings ranging from relatively normal to heavily damaged surface. The large mass was composed of a cord-like element and a fine net-like one. There was a transition between the thick, cylindrical fibers and the large mass. It is suggested that the thick, cylindrical fiber is an early event and the mass is more damaged, as one of the elastotic changes in solar elastosis. It is also suggested that the thick, cylindrical fiber corresponds to the fibrous form and the mass to the amorphous form of the elastotic material.

Aged↗

PubMedDate not supplied

[Comparative scanning electron microscopic study of Naegleria and Acanthamoeba (Hartmannella) cysts (author's transl)].

The present study was performed with the help of scanning electron microscope and refers to the external morphology of the cysts of the free-living amoebae. The amoebae belonging to the genus Naegleria form cysts whose outer layer shows no wrinkles. It can be smooth (N. fowleri) or rough (N. gruberi). The average number of pores varies between 1.2 and 7.2. Their margin can be smooth (N. fowleri) or pierced (N. gruberi). The thickness of the bordering cell wall varies between 0.4 and 1.0 micrometer and that of the pore is about 0.6 micrometer. The cysts of the genera Schizopyrenus, Tetramitus and Didascalus are very small, show no wrinkles in their cell wall and contain no pores. In contrast, cysts in the general Acanthamoeba show their outer layer superficially plugged with a lesser number of wrinkles (A. rhysodes, A. culbertsoni) or with large or deep wrinkles inside their wall (. castellanii, A. polyphaga). There are no pores observed in their cysts. Thus the distinguishing morphological features of the cysts have generated important role in the taxonomy of the amoebae of the limax-group.

Amoeba↗

PubMed1993

Ultrastructure of the chick vestibular ganglion and vestibular nucleus. A scanning electron microscopic study.

The fine structure of the chick vestibular ganglion and vestibular nucleus was studied in three dimensions using a scanning electron microscope (SEM). NaOH and OSO4 maceration methods were applied to observe the configuration in the mechanically torn specimens. Also, Tanaka's aldehyde prefix OSO4-DMSO-OSO4 method (A-O-D-O method) was applied to observe the intracellular structure in the fractured specimens. The surface of the ganglion cell and the nerve processes were seen to be covered with abundant thin fibrous tissues in the specimen treated with OSO4 maceration. This surface fibrous tissue was completely removed with the NaOH maceration method. As a result, the ganglion cell and nerve processes could be seen to be enveloped in the myelin sheath. In the fractured vestibular ganglion treated by the A-O-D-O method, there were three patterns of perikaryal myelination in the vestibular ganglion cells: heavily myelinated, lightly myelinated, and unmyelinated, respectively. In the perinuclear region of the vestibular ganglion cell, well developed and aggregated cytoplasmic organelles such as endoplasmic reticulum, mitochondria, and Golgi apparati were observed. In the perinuclear region of the Schwann cell relatively large mitochondria were characteristically observed. In the fractured view of the vestibular nerves, most of vestibular fibers were compactly myelinated. In the vestibular nucleus, the gathering of the neuronal cells were observed with the NaOH maceration method.

Animals↗

PubMed1989

Blood vascular beds of rat adrenal and accessory adrenal glands, with special reference to the corticomedullary portal system: a further scanning electron microscopic study of corrosion casts and tissue specimens.

Blood vascular casts of the rat adrenal glands were observed with a scanning electron microscope. The cortical capillary plexus drains, through the corticomedullary venous radicles, into the subcortical veins continuous with the medullary collecting veins. The medullary capillary plexus drains into the corticomedullary venous radicles, subcortical veins and medullary collecting veins. No portal vessel was noted between the cortical and medullary capillaries. These findings indicate that the cortical blood rich in glucocorticoids preferentially and continuously flows into the corticomedullary venous radicles, subcortical veins and medullary collecting veins all three of which are fenestrated in type, and also suggest that the vascular route from the cortical capillaries to the medullary collecting veins functions as a substitute for the portal system, controlling the biosynthesis of catecholamines in the adrenal medulla. The vascular bed of the accessory adrenal gland (extra-adrenal cortical or chromaffin body) is sometimes annexed to that of the adrenal gland. On rare occasions, the vascular beds of the extra-adrenal cortical and chromaffin bodies fuse with each other. Additional scanning of tissue samples confirmed the direct drainage of cortical capillaries into the medullary veins and also the endothelial fenestrations of these capillaries and veins.

Adrenal Glands↗

PubMed1978

[Light and scanning electron microscopic studies of structure of dentin interglobular spaces (author's transl)].

The author, after giving a literature survey, reports the results of scanning electron microscope examinations of interglobular spaces. The interglobular spaces are mineral-free regions within the dentin. They contain an organic matrix with a smaller amount of ground substance and a smaller number of collagenic fibrils than are contained in the matrix of mineralized dentin. Obviously, hollow spaces observed during microscopic examination are artifacts produced by shrinkage of the matrix despite good fixation. It has not so far been possible to obtain any indications of liquid-filled spaces.

Dentin↗

PubMed1980

A scanning electron microscopic study of the inorganic and organic matrices comprising the mature shell of Amblema, a fresh-water mollusc.

The scanning electron microscope has been used to describe the morphology of the mature shell in a fresh-water bivalve. The structure of the organic and inorganic components within the nacre, the myostracum, and the prismatic layer is described. A transitional or intermediate zone, interposed between the prismatic layer and the nacre, was identified. In demineralized samples, the organic component of the nacre was found to consist of parallel matricial sheets interconnected by irregular transverse bridges. The structure of the mineral component of the nacre was found to vary with the method of specimen preparation. With polished-etched samples, brick-like units were seen. When shells were simply broken and fixed in osmium, the layers of nacreous material consisted of fusing rhomboidal crystals of aragonite which demonstrated subconchoidal fractures. On the inner surface of the shell, the rhomboidal crystals showed an apparent spiral growth pattern. The myostracum was characterized by regions of modified nacreous structure consisting of enlarged aragonite crystals with a pyramidal morphology. The peripheral aspect of the muscle scars was characterized by rhomboidal crystals, the latter fusing to form the typical nacreous laminae. The uniqueness of the anterior adductor scar is exemplified by the presence of pores, each pore walled by pyramidal units, for the insertion of adductor fibres. In most regions of the shell, the prismatic layer consisted of one prism unit thickness with a height of approximately 225--250 micrometer. However, in two specialized regions of the shell, this layer was seen to consist of multiple layers of stacked prisms. The organic matrices of the prismatic layer are arranged in a honeycomb-like arrangement and packed with mineralized spherical subunits.

Animals↗

PubMed2004

Attachment and morphological behavior of human periodontal ligament fibroblasts to mineral trioxide aggregate: a scanning electron microscope study.

The attachment and morphology of human periodontal ligament fibroblasts to mineral trioxide aggregate (MTA) was evaluated using a scanning electron microscope. The material was placed at an apical cavity of 30 single-rooted slices of extracted human teeth. The specimens were divided into two groups of 15 root slices each (freshly mixed and set state). For each experimental group, five root slices were used per observation period (4, 8, and 24 h). A set of two glass slides was used per observation period for the control group. The experiments were performed in tissue-culture cluster 96-well plates in which 1 ml of human periodontal ligament fibroblast cell suspension was placed over the MTA filling and the control glass slides. For the positive-control group, 0.5 ml of methyl methacrylate 2% (vol/vol) was added to the cell suspensions before being dispensed into the wells. Results showed the normal cell morphology in the negative controls. Few round cells with less smooth surfaces and many rough blebs were seen in the positive control, and most of these cells did not show any attachment to the substratum. Similar observations were seen with the freshly prepared-MTA group. In the set-MTA group, cells were round and flattened, displayed smooth surfaces, and appeared to be tightly attached to MTA. It was concluded that the quality and quantity of cell attachment to the retrofilling material could be used as a criterion to evaluate material's toxicity. This research (FN#1077) is registered with the College of Dentistry research center, King Saud University, Riyadh, Saudi Arabia. The author thanks the administration of the King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia, and in particular Dr. M. N. Al-Ahdal for providing the use of the Molecular Virology and Infectious Disease Laboratory, Mr. Yunus Siddiqui for his support, and Dr. Saad AL-Nazhan for his assistance in preparing the manuscript.

Aluminum Compounds↗

PubMed1976

Experimental production of ridges on rabbit articular cartilage: a scanning electron microscope study.

The surface of normal rabbit articular cartilage attached to subchondral bone has a pitted appearance when examined with the scanning electron microsope. It is thought that these pits are similar to those seen in human cartilage and that they reflect the presence of underlying chondrocytes and lacunae, shrunken by preparative procedures. Ridges or undulations were not seen on the normal articular surface with the scanning electron microscope but complex systems of coarse and fine ridges were produced when cartilage was damaged by cutting, by making a hole in it or by detaching it from subchondral bone. Humps or mound-like elevations also developed in some instances when cartilage was damaged by cutting or by making a hole in its substance.

Animals↗