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At least 1,459 records · Page 81Linked to original sources
PubMed1992

Microvillus form of focal anchorage in human Chang liver cells rounded by antiporter activation: scanning electron microscopy profiles and evidence of traction origin.

Na+/H+ antiporter activation in human Chang liver cells produces a flat-to-round (FTR) change in cell shape with gross reduction in cell profile area. Scanning electron microscopy (SEM) vividly displays a third phenomenon, viz., the development of focal microvillus anchors. Reduction in cell profile area concomitant with the development of this microvillus form of focal anchorage is quantitated by on-line image analysis during SEM examination. The reduction in profile area is corroborated by spectrophotometric digitization in light microscopy. Transmission electron microscopy (TEM) of rounded cells shows large endocytic channels and endosomes consistent with the observation of internalization of fluoresceinated-dextrans (FDx) of a diverse range of sizes, from 4,400 to 2,000,000 molecular weight, with cell rounding. Concomitant endocytosis of this magnitude indicates massive plasma membrane internalizations which could explain the very considerable profile area reduction and suggest that the microvillus anchors are probably traction processes. Antiporter mediated rounding (AMR) provides a highly reproducible and simple model for the production of anchoring microvilli ('filopodia') whereby they can be further explored.

Carrier Proteins↗
PubMed2004

Insertion of GPI-anchored alkaline phosphatase into supported membranes: a combined AFM and fluorescence microscopy study.

A new method based on combined atomic force microscopy (AFM) and fluorescence microscopy observations, is proposed to visualize the insertion of glycosylphosphatidyl inositol (GPI) anchored alkaline phosphatase from buffer solutions into supported phospholipid bilayers. The technique involves the use of 27 nm diameter fluorescent latex beads covalently coupled to the amine groups of proteins. Fluorescence microscopy allows the estimation of the relative protein coverage into the membrane and also introduces a height amplification for the detection of protein/bead complexes with the AFM. The coupling of the beads with the amine groups is not specific; this new and simple approach opens up new ways to investigate proteins into supported membrane systems.

Alkaline Phosphatase↗
PubMedDate not supplied

Rapid and easy identification of Illicium verum Hook. f. and its adulterant Illicium anisatum Linn. by fluorescent microscopy and gas chromatography.

Illicium verum Hook. f. is used as an herbal tea to treat colic pain in infants. Reports suggest that Star anise herbal tea may be adulterated with Illicium anisatum Linn. A short and rapid method using microscopy and gas chromatography (GC) was developed to detect I. anisatum Linn., an adulterant in the powdered mixture of I. verum. Anatomical differences in the epicarp cells of I. verum and I. anisatum fruits were clearly defined as examined under fluorescent microscopy and scanning electron microscopy. A GC method was developed for quick identification of possible I. anisatum adulteration with I. verum.

Botany↗
PubMed2005

[Confocal scanning microscopy for biomedicine].

Confocal scanning microscopy is a new technique which can obtain the 3-D images of samples by using scanning and computer processing. It has been widely used in biomedical fields owing to its advantages such as high resolution and 3-D imaging. In this paper, we analyze the principle and research development of confocal scanning microscopies, and illustrate its advantages by comparing it with other microscopies.

Image Enhancement↗
PubMedDate not supplied

A study of primary dental enamel from preterm and full-term children using light and scanning electron microscopy.

PURPOSE: The aim of this study was to examine the enamel thickness of the maxillary primary incisors of preterm children with very low birth weight (< 1,500 g) compared to full-term children with normal birth weight. METHODS: A total of 90 exfoliated maxillary primary central incisors were investigated using light microscopy and scanning electron microscopy (SEM). Three serial buccolingual ground sections of each tooth were examined under light microscopy, and maximum dimensions of the prenatally and postnatally formed enamel were measured. RESULTS: The enamel of preterm teeth was approximately 20% thinner than that for full-term teeth. Most of the reduction was observed in the prenatally formed enamel. This was 5 to 13 times thinner than that for full-term children (P<.001). The "catch-up" thickness of postnatally formed enamel did not compensate fully for the decrease in prenatal enamel (P<.001). Although none of the teeth used in this study had enamel defects visible to the naked eye, 52% of preterm teeth showed enamel hypoplasia under SEM, compared with only 16% found on full-term teeth (P<.001). These defects were present as pits or irregular, shallow areas of missing enamel. CONCLUSIONS: Preterm primary dental enamel is abnormal in surface quality, and is significantly thinner compared to full-term enamel. The thinner enamel is due mainly to reduced prenatal growth and results in smaller dimensions of the primary dentition.

Child, Preschool↗
PubMed2006

A new technique for assessing hybrid layer interfacial micromorphology and integrity: two-photon laser microscopy.

PURPOSE: This study describes a two-photon laser fluorescence microscopy technique developed to evaluate the interfacial micromorphology of the hybrid layer in bonded restorations. MATERIALS AND METHODS: Micropermeability of the hybrid layer was characterized by means of simultaneously contrasting a dye-containing adhesive with a differently colored dye placed into the pulp chamber and allowed to diffuse toward the different-colored hybrid layer. A fluorescent red dye (rhodamine B) was incorporated into a commercial dentin bonding agent. Class I preparations (margins in enamel) were made on extracted human third molars. The teeth were restored using conventional methods: bonding agent, composite, finishing, and polishing. An aqueous solution of a yellow/green dye (fluorescein) was then placed into the pulp chamber for 3 h, allowing time to diffuse toward the different-colored bonded interface. The teeth were then embedded, sectioned, and microscopically analyzed using two-photon laser microscopy at 40X magnification. RESULTS: Subsurface fluorescent imaging using this technique enabled interfacial micromorphology to be characterized at submicrometer resolution and provided high-contrast images. The quality of surrounding structures and potential presence of gaps were also precisely assessed. CONCLUSION: Two-photon laser microscopy provided high quality, high-resolution images of the bonded interface and surrounding areas, allowing accurate qualitative and quantitative analysis of the structure and integrity of the hybrid layer.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1991

Light and electron microscopy of the structural organization of the tissue-lymphatic fluid drainage system in the mesentery: an experimental study.

Supplementing vital microscopy and histophysiology, we examined using combined light and electron microscopy the tissue fluid-lymphatic drainage system of the mesentery isolated from guinea pigs, rabbits, and tree shrews. In silver impregnated tissue, different types of lymphatics and blood vessels were able to be distinguished along with argyrophilic and argyrophobic structures in the connective tissue. Some initial lymphatic pathways were interrupted by non-endothelialized tissue zones thus forming separate but discrete vascular "islands". After carbon labeling of the lymphatic collectors, carbon particles were seen to escape from the initial lymphatic lumen at various sites. Electron microscopy revealed wide apertures in the lymphatic endothelial cells of these microvessels. These morphological findings support the concept of an "open" prelymphatic-lymphatic system in the mesentery. The special histometrical features exhibited by a flat membranous organ like the mesentery are discussed in terms of physiologic function of mesenteric tissue fluid transport.

Animals↗
PubMed1990

Correlative light, transmission, and high resolution (SE-I) scanning electron microscopy studies of rhesus adrenocortical vascular morphology.

A detailed correlative morphologic description using light microscopy (LM), transmission electron microscopy (TEM) and high resolution SE-I scanning electron microscopy (SEM) was conducted on the capillary endothelium of the zona-fasciculata (Z-F) in juvenile male rhesus monkeys. The glucocorticoid synthesis and release phenomena, associated with stress stimulated release of adrenocorticotropic hormone (ACTH) via the hypothalamic-pituitary axis, intimately involves capillaries of the Z-F. A comprehensive study of all the ultrastructural features implicated in the transendothelial uptake of steroidogenic precursors and release of glucocorticoids in perfused rhesus adrenals has not previously been made. This report presents correlative images of transendothelial openings that include previously described single diaphragmed fenestrae and plasmalemma vesicles, and double diaphragmed transendothelial channels. New observations of endothelial cell pockets, tight junctional complexes and membrane filled ghost sacs were recorded from perfused rhesus adrenal. Membranous ghosts associated with adrenocortical endothelium were reported in a previous TEM study of perfused rat, however the potential argument existed that ghosts were artifactual. Their role as steroid hormone releasing structures remains an open question, yet their structural characteristics appear justified based on imaging of identical profiles observed in perfused rhesus adrenocortical specimens. These structural features are considered for the potential of gating and sorting of metabolites, and release of glucocorticoids in response to ACTH stimulated stress events.

Adrenal Cortex↗
PubMed1989

Recent uses of electron microscopy in the study of physico-chemical processes affecting the reactivity of synthetic and biological apatites.

Studies which used scanning electron microscopy (SEM) to investigate subsurface demineralization of dental enamel have recently been well reviewed. The purpose of the present paper was to review several studies, carried out in our laboratories, which have used electron microscopy to examine physicochemical properties of synthetic and biological apatites, to relate these results to previous studies, and to present new data. Aspects of the ultrastructure of hydroxyapatite and carbonated-apatites have been observed by high resolution transmission electron microscopy, and related to shape and growth of these crystals. Surface morphologies of discs prepared from precipitated carbonated-apatites and from ceramic carbonated-apatites were examined by SEM and the information was used in the interpretation of apatite dissolution studies relevant to dental caries. Improvements in the technique of backscattered electron imaging of demineralized enamel have enabled better interpretation of enamel caries experiments. SEM examination of enamel and dentin treated by low energy lasers of specific wavelengths have shown that lasing conditions can be chosen that produce surface fusion of the apatite which inhibits caries-like lesion progression. SEM examination of crystals formed on and in enamel during high concentration fluoride treatments implies that calcium fluoride-like crystals are formed and they may act as a slow-release fluoride reservoir in the mouth.

Apatites↗
PubMed1987

Morphological changes in the isolated rat liver perfused in a non-recirculating system: scanning and transmission electron microscopy.

Isolated perfused rat livers have been used for various studies, but detailed investigation into the structural integrity of hepatocytes of this system is lacking. In this study, isolated rat livers were perfused in vitro with oxygenated Krebs-Ringer bicarbonate buffer solution, for 2 minutes and 1, 2, 3, and 4 hour(s) at 37 degrees C, using a non-recirculating perfusion system. The perfused livers were processed for semithin section light microscopy, transmission electron microscopy, and scanning electron microscopy. Sectional areas of cell deaths were measured by a camera-tracing assembly from 1.5 microns thick Araldite sections stained with toluidine blue. Progressive nuclear and cytoplasmic changes, leading to cell death, occurred in the hepatocytes of the centrilobular zone, during the 2nd, 3rd, and 4th hour of the perfusion at a rate of 9.03% +/- 1.5%, 38.7% +/- 2.7%, and 55.1% +/- 5.9% (mean +/- standard deviation) of the total sectional areas respectively. Midzonal hepatocytes showed normal basophilic staining but exhibited loss of glycogen granules, loss of microvilli, development of aqueous vacuoles and formation of blebs. The fine structures of cell organelles, glycogen granules, microvilli and plasma membrane of the cells in the periportal zone were well preserved throughout the experimental period. For further quantitative, metabolic and functional studies using isolated rat liver perfused with Krebs-Ringer solution, it is evident from the present investigation that the periportal zone represents the functional region of the hepatic lobule. Whilst progressive changes, leading to cell death, occurred in the centrilobular zone.

Animals↗
PubMed1987

A new type of substratum adhesion structure in NRK cells revealed by correlated interference reflection and electron microscopy.

The substratum adherent membrane of NRK cells in vitro has been studied using correlated interference reflection and surface replica electron microscopy. Structures visualized by interference reflection microscopy were identified in the subsequently prepared platinum-carbon replicas of the adherent membranes. Substratum adherent membranes were prepared using a hypotonic shock/cell shearing technique (lysis-squirting). Typically 20% of the original ventral membrane surface area and 50% of the original focal adhesion number were retained. Microfilament bundle termini, clathrin-coated sheets and pits, cytotic vesicles having a ridged surface and groups of membrane associated particles were well preserved in the replicas. Two types of isolated adhesion structures were found after lysis-squirting. In addition to typical elongate focal adhesions containing actin and vinculin, we report the existence of adherent membrane patches lacking microfilament bundles and negative for vinculin labelling, but coated with clathrin and identifiable in interference reflection microscopy as less dark than focal adhesions and having dot, U- or sinusoidal shapes.

Actin Cytoskeleton↗
PubMed1988

Changes in the tracheal ciliated cells in rabbits treated by cis-diamminedichloroplatinum (II) as studied by electron microscopy.

The ciliated epithelium of the rabbit's trachea was investigated after a single 5 mg dose of cis-diamminedichloroplatinum (cis-DDP). Specimens were taken for scanning electron microscopy, transmission electron microscopy and light microscopy. Examination was performed daily for 20 consecutive days. A cytotoxic effect of the drug on the ciliated epithelium was observed with bent ciliary tips, swollen tips and broken cilia. Finally the cilia were lost and large areas of the surface were covered with microvilli. However, 20 days after the drug injection, the restitution of the ciliary carpet was almost complete.

Animals↗
PubMed1973

Differential interference contrast microscopy of human atherosclerotic lesions.

Differential interference contrast microscopy was employed to study sections of human cerebral arteries and aorta. When this procedure was used to observe 0.5-mu-thick sections of plastic-embedded arteries, images were obtained with greater definition of detail than corresponding micrographs of the area using conventional bright-field microscopy. Since structures with different refractive indices are shown in geometric relief from one another, an apparent three-dimensional image is seen, which, together with the theoretically higher resolution and contrast achieved by this technic, gives an image with definition between conventional light and low magnification electron microscopy. The morphology of fatty streak lesions with aggregates of round and elongated lipid-filled cells was demonstrated, and clear images of different forms and sizes of intracellular lipid droplets were illustrated at magnifications around 1000. In atheromatous plaques, intra- and extracellular lipid droplets were observed, some with partially extracted cores or surfaces, as were amorphous lipid droplets coalescing with crystals whose centers had been extracted. We conclude that this optical accessory to a research photomicroscope is a valuable supplemental tool in studies on the morphology of atherosclerotic lesions.

Aorta↗
PubMed1979

Investigation of crystallosis of the kidney by means of polarization, scanning, transmission and high-voltage electron microscopy.

This report deals with the investigation of renal crystallosis in the autopsy tissue of a fatal human case of ethylene glycol poisoning. A previously healthy 22-year-old man consumed about one liter of Prestone antifreeze, which contains 95% by weight of ethylene glycol. He died in coma 48 h later with clinical evidence of metabolic acidosis and renal shutdown. Postmortem histological examination showed abundant crystallosis of the renal tubules. Polarization microscopy demonstrated brilliant birefringence of the crystals. In addition to the tubular crystallosis, scanning electron microscopy showed crystalline particles within the glomeruli as well. Energy dispersive X-ray analysis of the crystals gave a strong calcium signal. The crystals were demonstrated by means of conventional and high-voltage electron microscopy. Electron diffraction gave several hexagonal patterns of calcium carbonate-calcite and a tetragonal pattern suggestive of calcium oxalate monohydrate. X-ray diffraction of the crystals separated from the kidney showed the presence of calcium carbonate and calcium oxalate monohydrate as the major constituents.

Adult↗
PubMed1979

Scanning and transmission electron microscopy of the blood-bubble interface in decompressed rats.

Scanning and transmission electron-microscopy have been applied for study of the ultrastructural features of the blood-bubble interface in the vasculature of explosively-decompressed rats. In scanning electron-microscopy, the surface facing the bubble appeared smooth, with slight undulation and frequent roundish protrusions. In cross sections of the material between the bubbles, there could be observed a continuous surface layer facing the bubble, a loosely-bound meshwork of fibrous material, and extreme congestion of erythrocytes. In transmission electron-microscopy there were found alignment of platelets along the interface, and a thin (10-20 nm) layer of osmiophilic material, in accordance with earlier ultrastructural studies. The platelets were often rounded. It is concluded that the initial phase of the blood-bubble interaction is the deposition of a plasma protein coat, followed by the attachment platelets, possibly related to activation of the coagulation system.

Animals↗
PubMed1977

Correlative scanning and transmission electron microscopy of glomeruli.

Scanning electron microscopy was performed on 125 human renal specimens and control rat kidneys in conjunction with light microscopy and transmission electron microscopy. Specimens were prepared by glomerular isolation, free hand slicing, alcohol cryofracture, and polyethylene glycol embedding and ultraplaning. Heavy metal secondary electron sources on the tissues were produced by osmic acid, thiocarbohydrazide, osmic acid treatment (O-T-O) followed by gold-palladium coating, or by staining with uranyl acetate and lead citrate. Critical point drying was used uniformly. Useful observations of normal rat glomeruli were made. In the study of diseased human glomeruli, podocyte changes were classed as cytoplasmic projection, foot process changes, and changes of necrosis or basement membrane denudation. Artificial lesions of compression and contamination were defined. Cryofractured and ultraplaned stained specimens were very useful for studying diseased tissues. These methods offer the opportunity to increase our conceptual and diagnostic understanding of glomerular disease.

Animals↗
PubMedDate not supplied

Follicular carcinoma of the human thyroid gland: an ultrastructural study with emphasis on scanning electron microscopy.

Previous ultrastructural studies on follicular thyroid carcinomas present conflicting results, in particular with regard to the surface features of the neoplastic cells. The present study of 9 cases with varying degrees of differentiation is the first comprehensive investigation by concurrent transmission and scanning electron microscopy. In the well-differentiated tumours we found a slightly increased number of microvilli and a decreased number of cilia per cell as compared to the normal thyroid follicles, while moderately differentiated tumours had a smaller number of microvilli and no cilia. The cells in anaplastic foci had unimpressive surfaces with only scattered clusters of short microvilli. Neither scanning nor transmission electron microscopy seem to be of major importance in the diagnostic evaluation of the individual case of follicular thyroid carcinoma or in the assessment of prognosis. Scanning electron microscopy presents a wealth of information on the three dimensional surface arrangement of the neoplastic cells. However, in a tumour where surface alterations may reflect both changes in endocrine function and malignant potential, the interpretation of isolated morphological findings is extremely difficult.

Adenocarcinoma↗
PubMed1980

Scanning and transmission electron microscopy of the rugose portion of the human endolymphatic sac--a preliminary report.

The rugose portion of two human endolymphatic sacs--one from a Meniere's disease patient, the other from a patient who underwent removal of an eighth nerve tumor and had no other evidence of inner ear disease--has been examined by scanning and transmission electron microscopy. The only morphological finding that distinguished the normal from the Meniere's disease specimen was more folds in the epithelium of the normal sac. Two types of cells have been distinguished in the two sacs through both scanning and transmission electron microscopy: cuboidal-to-columnar cells with a convex luminal surface and microvilli, and squamous cells with a flat luminal surface and microvilli. Qualitative differentiation of the two specimens according to frequency of cellular type or difference in cellular or microvillar morphology was not possible. Observations of this study on the epithelial morphology of the rugose portion did not correspond with descriptions of the epithelial morphology in animals. It is, therefore, tentatively concluded that the morphology of the rugose portion of the human endolymphatic sac is different from that of animals. This study suggests that scanning electron microscopy can be used to determine the number and location of cell types and/or the quantity of microvilli in the rugose portion of the endolymphatic sac. Comparison of measurements of normal endolymphatic sacs and those from Meniere's disease patients may demonstrate significant differences.

Ear, Inner↗