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At least 1,207 records · Page 67Linked to original sources
PubMed1977

Surface structure of tooth germs from newborn infants: a light and scanning electron microscopical study.

Tooth germs from the mandibles of 5 stillborn infants were examined by scanning electron microscopy and light microscopy in order to investigate the surgace structure at different stages of mineralization. The surface of the completed enamel of the incisal third of the incisors was smooth, indicating that amelogenesis was at an end. The interface relief between ameloblasts and enamel matrix on the remaining part of the incisors, and on the forming cusps, was characterized by numerous deep pits caused by the Tomes' processes of the ameloblasts. When parts of the organic matrix were removed by sodium hypochlorite, the crystals were exposed as needle-shaped structures. Towards the bases of the cusps the pits gragually smoothed out, continuing as a narrow even surface zone corresponding to the first formed aprismatic enamel. In this zone circular holes 1 micronm were encountered which the light microscope studies showed were dentinal tubules passing into the enamel. At the bases of the cusps there was a rather abrupt demarcation toward a surface zone exhibiting countless slender villi. The light microscope observations indicated that these villi represented the first formed dentine after the basement membrane had disappeared.

Amelogenesis↗
PubMed1979

Examination of peripheral nerves with the scanning electron microscope.

The theoretical applications and advantages of the scanning microscope in peripheral nerve research are presented. The internal anatomy of the peripheral nerve can be distinctly examined, and long segments of axons can be examined without the necessity of tedious study of multiple sections. The SEM should make it possible to more readily study the migration of axon sprouts across a repair site. New concepts in teaching and research may develop from the use of this excellent tool.

Animals↗
PubMed1980

Secretory mechanisms of human ceruminous glands: a transmission and scanning electron microscopic study.

Two secretory mechanisms (eccrine and apocrine) were observed by transmission and scanning electron microscopy in the same secretory cells of the human ceruminous glands. The eccrine secretion occurs as a typical exocytosis by fusion of the limiting membrane of the secretory granule with the apical plasmalemma. The apocrine secretion is more complex and takes place by sequential steps: bulging of the cellular apex into the lumen, constriction of the projection, and detachment of it from the cell. This mechanism generally causes the removal of the entire projection all at once by decapitation at its base; some variations of this process have been found, however, and are described in the present work. A double membrane, apparently separating the apical protrusion from the rest of the cell, is noticeable in our photographs. Nevertheless, even if this membrane is very similar to a demarcation layer, we consider it as an intercellular double membrane separating two obliquely sectioned cells.

Adolescent↗
PubMed1992

The effect of endolymphatic sac obliteration on vestibular sensory hair bundles. A high-resolution scanning electron microscopic investigation.

A tannic acid-osmium staining technique and high-resolution scanning electron microscopy were used to demonstrate changes in the glycocalyx and ciliary interconnections of the vestibular sensory cells of guinea pigs after extradural obliteration of the endolymphatic sac and duct. Three months after the obliteration, it was possible to observe degeneration in the glycocalyx and the ciliary interconnections as well as the tip links. These findings suggest that the endolymphatic hydrops causes an endolymphatic ionic imbalance which affects the glycocalyx and ciliary interconnections resulting in further morphological changes of the cilia. The tip links, which are believed to be involved in sensory cell transduction, also seem to be affected.

Animals↗
PubMed1979

[Cytoenzymological, immunological and scanning electron microscopic studies on 49 cases (author's transl)].

Light cytology, enzymology, immunofluorescence and scanning electron microscopy have been performed on 49 bronchoalveolar fluids recovered by bronchoscopic lavage. The patients had the following lung diseases: infectious pneumonitis (19 cases), pulmonary fibrosis (13 cases) including 5 sarcoïdosis, 3 idiopathic pulmonary fibrosis and 5 silicosis, hypersensitivity pneumonitis (5 cases) and miscellaneous lung tumors (12 cases). Cytologic studies in comparison with clinical aspects show 4 groups: Group I (chronic bronchopneumopathy and inactive fibrosis) presents numerous cells but few lymphocytes (less than 5%); in Group II (evolutive fibrosis) have an increase percentage of lymphocytes (20%); in Group III (hypersensitivity pneumonitis) is observed a very high percentage of lymphocytes (45%); and in Group IV (cancerous lung diseases) values are not far from normal percentage except for lymphomas. Small macrophages (diameter: 10 microns) with a central monocytoïde nucleus and few cytoplasma, are abundant in groups II and III where lymphocytosis is higher. Scanning electron microscopy shows irregular and rough surface, and numerous spontaneous adherences with erythrocytes, lymphocytes, or bacterias. Enzymatic activity (acid hydrolase, esterase, oxydase) increases in these cells. Lymphocytes have a smooth surface ovocative of T origin which is confirmed by granular acid phosphatase positivity and rosette forming test. Immunofluorescence shows positive granules with IgG, C1Q and C3 in macrophages only for Groups II and III while free immunoglobulins were present in the recovered lavage fluid.

Bronchi↗
PubMed2000

Tubular contents of equine dentin: a scanning electron microscopic study.

The dentinal tubules of 20 permanent equine incisors were investigated by scanning electron microscopy. Occlusal surfaces and longitudinal fracture planes of both etched and undecalcified teeth were examined. Three different types of structure were observed inside the dentinal tubular lumen. Odontoblastic processes could only be visualized in the circumpulpal parts of the tubules. The more peripheral parts were empty or housed cylindrical structures that probably correspond to the laminae limitantes. Collagen fibres were frequently observed in the tubular lumina and were most numerous in the circumpulpal parts of the tubules.

Acid Etching, Dental↗
PubMedDate not supplied

Three-dimensional structure of oncocyte mitochondria in human salivary glands: a scanning electron microscope study.

Oncocytes occurring in otherwise normal human salivary glands were examined by scanning electron microscopy after being subjected to a maceration technique that removes all soluble cytoplasmic components and leaves only membranes in place. The three-dimensional images resulting from this procedure confirm that the majority of oncocyte mitochondria have shelf-like cristae that are attached to the inner boundary membrane, often by means of tubular structures. In some mitochondria, the cristae are digitiform and, when transected, give rise to putative vesicles. The oncocytic mitochondria in human salivary glands, by and large, lack the structural irregularity that has been reported for these organelles occurring in oncocytes in other organs.

Aged↗
PubMed1996

Morphologic differences of the vascular buds in the vertebral endplate: scanning electron microscopic study.

STUDY DESIGN: Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts. OBJECTIVES: To examine morphologic differences between vascular buds in two regions of the vertebral endplate (inner anular and nucleus pulposar). SUMMARY OF BACKGROUND DATA: Vascular buds are specific structures present at the vertebral endplate that are important as nourishing channels. There is a significant difference in permeability between the lateral portion (inner anular) and the central portion (nucleus pulposar) of the endplate, the latter usually being permeable and the former being impermeable. Morphologic differences between vascular buds in the two regions have not been investigated previously. METHODS: Eight 20-week-old rabbits were used. Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts. RESULTS: The vascular buds in the region of the inner anulus form simple loops, but those in the area near the nucleus pulposus exhibit swollen and complex coil-like loops. Although they differ structurally, the average number of vascular buds per area does not vary between the two regions. CONCLUSIONS: We suggest that the morphologic difference between the vascular buds in the two regions (inner anular and nucleus pulposar) plays a principal role in permeability at the endplate.

Animals↗
PubMed1989

Amelogenesis imperfecta: a scanning electron microscopic and microradiographic study.

The aim of the present study was to use scanning electron microscopy (SEM) to visualize the morphology of the enamel surface in 12 primary teeth from children with amelogenesis imperfecta (AI). The observations were correlated to genetic, clinical and microradiographic data from the same teeth and to non-affected control teeth. SEM showed similar disturbances in teeth with a clinical predominance of hypoplasias and in teeth with a predominance of hypomineralization. In the microradiographs the enamel of most teeth showed both hypoplasias and areas of hypomineralization, independently of the predominant clinical manifestation. In the one boy with an X-linked inheritance pattern, both SEM and microradiography showed the morphology of the enamel to be unique in the present study. In the other teeth, similar manifestations were found in cases with AI as an AD trait and in the sporadic cases.

Amelogenesis Imperfecta↗
PubMed1977

Endocardial surface structures of the feline heart observed with a scanning electron microscope.

Internal surface structures of the auricular and ventricular chambers were studied with scanning electron microscopy. We observed vascular connections between the ventricular chamber and the coronary vessels, including cords and papillary muscles covering the lining of the endocardium. The endothelial cells covering the inner surface of the endocardium appeared to be functionally active with many microvilli similar to pinocytic microprojections of other endothelial cells. The pinocytic microprojections ranged between approximately 100 and 300 A in diameter. The epicardium contained mainly bundles of collagenous fibers.

Animals↗
PubMed2002

Surface structures of aural polyps: a scanning electron microscopic study.

Surfaces of aural polyps collected from 30 patients were examined by scanning electron microscopy. In the polyps not associated with cholesteatoma, the epithelial lining showed individually variable metaplasia towards cuboidal 'cobblestone'-type and squamous epithelium covered with microvilli of various shapes and sizes. Squamous epithelium was present on the surface of all polyps with underlying cholesteatoma, with superficial cells possessing elongated microvilli, microplicae of different sizes, grooves and pits. Such surface structures reflect different stages of the keratinization process that seems to be characteristic for the epithelial lining of polyps with underlying cholesteatoma. Incomplete epithelium accompanied by granulation tissue was found in several polyps; in two cholesteatoma-associated polyps plate-like cholesterol crystals were observed.

Adolescent↗
PubMed1987

Scanning electron microscopic investigation of the afferent arteries of experimental femoral arteriovenous fistulae in rabbits.

Scanning electron microscopy of the intimal surface of anastomosed arteries of experimental femoral arteriovenous fistulae in rabbits was conducted to determine whether the muscular femoral artery differed from the elastic common carotid artery in its response to the hemodynamic stress of the arteriovenous shunt. Control femoral arteriotomies were performed in an additional five rabbits. The animals were sacrificed at varying intervals from 2 days to more than nine months postoperatively. Within two days postoperatively transverse and longitudinal tears involving the internal elastic lamina and also the endothelium appeared in the afferent artery as far proximal to the fistula as the lower abdominal aorta. Tears distal to the fistula were fewer and later in appearance. The tears healed rapidly. The response as demonstrated by this technique was similar to that of the common carotid artery of carotid-jugular fistulae except that tears appeared earlier postoperatively with longitudinal as well as transverse disposition. Similar tears were found in four of the five control arteriotomies in the vicinity of the suture or at the site of clamping. The experiments reveal the readiness with which hemodynamic stress induces intimal tears.

Animals↗
PubMed1979

Scanning electron microscopic study of follicular lymphoma.

Nine cases of follicular lymphoma were studied by scanning electron microscopy. The morphological findings by this method emphasizes the heterogeneity of the cellular composition of the follicles, even in the cases not labelled as mixed type, and the degree to which the anatomy of a normal secondary follicle is mimicked. Large nonlymphoid cells, presumably dendritic, are present in the follicles. There are no differences in the surface features of the follicular and interfollicular lymphoid cells.

Humans↗
PubMed1998

Innervation of blood vessels in the rat incisor pulp: a scanning electron microscopic and immunoelectron microscopic study.

Although two types of nerve endings have been proposed to innervate blood vessels in the dental pulp, the precise innervation pattern is not well understood. This is mainly due to the lack of information regarding the positional relationships of nerve fibers with blood vessels at the electron microscopic level. The rat incisor pulp was investigated by scanning electron microscopy (SEM) after connective tissue digestion and by transmission electron microscopy after immunohistochemical localization with polyclonal anti-PGP 9.5 antibody. SEM specimens revealed that unmyelinated nerve fibers passed through the tunica adventitia of the blood vessel in the center of the pulp and that these fibers then entered the tunica media of the smaller arterioles. The nerve fibers divided into many collaterals, and these terminated on the surface of smooth muscle cells and endothelial cells. The fibers extended toward smaller vessels. The terminal fibers then reached the subodontoblastic capillary plexus and terminated on pericytes, while the odontoblastic capillary plexus had no direct innervation. In the pulpal venules, nerve fibers were located adjacent to the pericytes and endothelial cells, and they extended toward postcapillary venules. The same results were confirmed by immunoelectron microscopy. The present study demonstrated that in the rat incisor pulp the microvasculature as well as larger vessels were directly innervated by free nerve endings, suggesting that the local regulation of blood flow could take place not only at larger vessels but also at the level of the microvasculature in this tissue.

Animals↗
PubMedDate not supplied

Imaging of specimens at optimized low and very low energies in scanning electron microscopes.

The modern trend towards low electron energies in scanning electron microscopy (SEM), characterised by lowering the acceleration voltages in low-voltage SEM (LVSEM) or by utilising a retarding-field optical element in low-energy SEM (LESEM), makes the energy range where new contrasts appear accessible. This range is further extended by a scanning low-energy electron microscope (SLEEM) fitted with a cathode lens that achieves nearly constant spatial resolution throughout the energy scale. This enables one to optimise freely the electron beam energy according to the given task. At low energies, there exist classes of image contrast that make particular specimen data visible most effectively or even exclusively within certain energy intervals or at certain energy values. Some contrasts are well understood and can presently be utilised for practical surface examinations, but others have not yet been reliably explained and therefore supplementary experiments are needed.

Journal Article↗
PubMed1975

Scanning electron microscopic study of virulent and avirulent colonies of Neisseria gonorrhoeae.

A preparation procedure for scanning electron microscopy was developed by which gononcoccal colonies can be studied directly on the agar surface. After glutaraldehyde fixation directly in petri dishes, small agar pieces were cut out and dehydrated stepwise in increasing concentrations of ethanol. The blocks were thereafter transferred to a critical-point drying apparatus, via steps of increased gradients up to 100% amyl acetate. By this method five different gonococcal colony types could be distinguished analogous to light microscopic observations made by others. At higher magnifications an abundance of intercellular strands was found between the cells in virulent type 1 and 2 colonies, but not in the avirulent types 3 through 5. These strands seemed to anchor the cells to each other and to the agar surface. The presence of such structures probably explains the highly convex surface of virulent colonies and explains why colonies of avirulent strains exhibit a radial extension and a flat upper surface. The nature of these filamentous intercellular strands is discussed.

Amylases↗