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At least 163 records · Page 9Linked to original sources
PubMed1975

The morphology of growth cartilage using the scanning electron microscope.

The authors undertook a scanning electron microscopic study of the layers of the growth cartilage in the distal end of the rabbit femur in longitudinal and transverse fractures. The relationships between the various morphological structures were determined. The three-dimensional spatial depiction facilitates the better understanding of some mutual relationships between various growth cartilage components. Especially interesting are the regressive processes in both the cells and the matrix which explain the reduction of mechanical strength in the zone of the hypertrophic cells. Also interesting is the way in which the cells are placed and fixed in the lucunae. Moreover, the spatial picture of the terminal plate shows an unexpectedly compact structure.

Animals↗
PubMed1997

Imaging thin and thick sections of biological tissue with the secondary electron detector in a field-emission scanning electron microscope.

A field-emission scanning electron microscope (FESEM) equipped with the standard secondary electron (SE) detector was used to image thin (70-90 nm) and thick (1-3 microns) sections of biological materials that were chemically fixed, dehydrated, and embedded in resin. The preparation procedures, as well as subsequent staining of the sections, were identical to those commonly used to prepare thin sections of biological material for observation with the transmission electron microscope (TEM). The results suggested that the heavy metals, namely, osmium, uranium, and lead, that were used for postfixation and staining of the tissue provided an adequate SE signal that enabled imaging of the cells and organelles present in the sections. The FESEM was also used to image sections of tissues that were selectively stained using cytochemical and immunocytochemical techniques. Furthermore, thick sections could also be imaged in the SE mode. Stereo pairs of thick sections were easily recorded and provided images that approached those normally associated with high-voltage TEM.

Animals↗
PubMed1986

The blood hepatocytic barrier: a light microscopical, transmission- and scanning electron microscopic study.

The normal blood hepatocytic barrier (BHB), comprised by the endothelial lining cells and the perisinusoidal space, was investigated, and it was concluded that the BHB is a complex structure in which each individual part serves several functions. Immunohistochemical staining for factor VIII showed endothelial lining cells to be positive. By TEM and SEM the endothelial cells were seen to be fenestrated without a basal lamina. They possess numerous endocytotic vesicles. The perisinusoidal space contains the lipocytes and a matrix composed of fibrils, and a microfilamentous to granular material. The nature of these matrix components was poorly analyzable by conventional methods. Lipocytes were visualized by LM in: sections stained with oil red 0 after fixation in Baker's formol-calcium and following post-fixation in dichromate, and toluidine-blue-stained Epon-embedded sections. TEM revealed numerous cytoplasmic processes rich in microfilaments encircling the sinusoids.

Azo Compounds↗
PubMed1979

Morphogenesis of rod cells in the retina of the albino rat: a scanning electron microscopic study.

This study presents scanning electron microscopic (SEM) observations of topographical changes that occur during morphogenesis of rod cells in the albino rat. Correlative transmission electron microscopy (TEM) was also utilized. Albino rats ranging in age from birth to three weeks were used for the study. Tissues were prepared by conventional methods for SEM and TEM. At birth, numerous irregularly arranged inner segments extend from the external surface of the sensory retina. They are spherical, smooth surfaced and possess a randomly oriented cilium. The internal morphology of these immature inner segments is comparable to that observed in other vertebrate species. Statistical analysis reveals a rapid increse in the number of rod cells during the first week. This period is characterized by the elongation of inner segments and their associated cilia. Microvilli project from the apices of Müller cells, but not from adjacent inner segments. By day 5, cilia occasionally display small bulbous outer segments. They are more numerous by day 8 and are usually eccentrically positioned at the tips of cilia. By day 11, outer segments are abundant and frequently obscure from view the underlying inner segments and associated cilia. Elongated cylindrical outer segments are present within the posterior retina at the end of the second week. However, rod cell morphogenesis lags in the peripheral retina. Topographical variations between developing photoreceptor cells in mammalian and non-mammalian retinas are discussed.

Aging↗
PubMedDate not supplied

An experimental model of beam broadening in the variable pressure scanning electron microscope.

In the variable pressure scanning electron microscope (VP-SEM) the incident electrons pass through a gaseous environment and the beam is scattered by these interactions. We show here that the experimental intensity profile of the scattered beam can be described as Gaussian in form to a high level of accuracy. This provides a rapid means of accounting for the effects of beam scatter in imaging and microanalysis because the standard deviation of the Gaussian is a simple function of parameters such as working distance, beam energy, gas type and pressure.

Journal Article↗
PubMed1993

Early morphogenesis of persistent hyperplastic tunica vasculosa lentis and primary vitreous (PHTVL/PHPV). Scanning electron microscopic observations.

This study provides scanning electron microscopic observations on the early morphogenesis of persistent hyperplastic tunica vasculosa lentis and primary vitreous (PHTVL/PHPV) in canine fetuses at days 28 35 postcoitum (D28 and D35). From previous studies regarding PHTVL/PHPV it is known that a retrolental plaque of fibrovascular tissue is present in eyes of affected canine fetuses from the D33 stage. The contribution of vitreous cells to the formation of the plaque is supported by the results of this study. The lens capsules at the stages described were not found to contain abnormalities such as transparent (thinner) parts or rents, as have been described for postnatal cases of PHTVL/PHPV. These findings support the hypothesis that the capsular anomalies observed in postnatal patients are secondary entities.

Animals↗
PubMed1994

A high resolution study of the glycocalyx of rat uterine epithelial cells during early pregnancy with the field emission gun scanning electron microscope.

The field emission gun scanning electron microscope has been used to investigate morphological changes at the macromolecular level in the glycocalyx of rat uterine luminal epithelial cells during early pregnancy. This very high resolution microscope has allowed visualisation at a level previously unobtainable and has enabled us to establish that dramatic alterations occur in this glycocalyx at the time of blastocyst attachment. On d 1 of pregnancy a prominent, filamentous glycocalyx radiates from the microvilli. However, by d 6 of pregnancy when the microvilli have been replaced by irregular cell surface protrusions, the glycocalyceal filaments are completely lost and the plasma membrane appears smooth and covered with a felt-like coating. These morphological observations suggest a major reorganisation in surface carbohydrates during early pregnancy and extend histochemical observations on the uterine epithelial glycocalyx.

Animals↗
PubMed1987

In vitro effect of praziquantel on Paragonimus westermani by light and scanning electron microscopic observation.

The effect of praziquantel on P. westermani exposed in vitro was observed by stereomicroscope, light microscope and scanning electron microscope. Following results were found. The worms incubated in 0.01 micro-g/ml praziquantel were moving after 26-hour incubation. However, all of them were immobilized immediately after incubation in solutions over 0.1 micro-g/ml concentration. All of the exposed worms showed severe vacuolization not only in tegument but in subtegument, intestine, ovary, testis, Mehlis' gland and excretory bladder. Vacuoles in tegument burst out to form craters. As incubation time went on, tegumental structure was disintegrated severely. The worms exposed to praziquantel were observed to be immobilized and be vacuolized of all tissues. Disintegration of reproductive organs suggests that praziquantel have suppressive effect on egg production when the flukes are not killed. The drug effects were found more related with incubation time than with drug concentration.

Journal Article↗
PubMed1997

Marginal fit consistency of copy-milled all-ceramic crowns during fabrication by light and scanning electron microscopic analysis in vitro.

The aim of this study was to evaluate the marginal fit of copy-milled Celay In-Ceram crowns after different fabrication steps and to compare light-microscopic with scanning-electron-microscopic data. A master steel die of an upper middle incisor with a shoulder preparation and a rounded inner line angle was used. Impressions were taken to produce 10 working stone dies. One crown per working die was manufactured. The evaluation of the external marginal gap was performed on the master steel die by using a light microscope and a computerized video image analysis system after copy milling (A), glass infiltration (B), and veneering (C). Approximately 3900 readings were taken. In a final series the veneered crowns were measured by using a scanning electron microscope (Cs), yielding approximately 1000 readings. The results obtained were: A mean, 25.1 microm; s.d., 5.1 microm; range, 2.5-76.8 microm: B mean, 20.6 microm; s.d., 2.3 microm; range, 2.5-76.1 microm: C mean, 18.3 microm; s.d., 4.1 microm; range, 2.5-87.2 microm: Cs mean, 23.0 microm; s.d., 7.6 microm; range, 0.0-94.5 microm. The results were statistically evaluated using the t-test. The differences found between the series did not show practical relevance. Therefore, it is concluded that the manufacturing steps after copy milling have no obvious influence on the external marginal gap width. Scanning electron microscopic data seem to confirm the light-microscopic results. Hence, we expect that the Celay In-Ceram method yields a clinically acceptable marginal fit.

Aluminum Oxide↗
PubMed1994

[Osteogenic potential of rabbit dermal fibroblasts cultured in vitro: a histochemical and scanning electron microscopic study].

Split-thickness rabbit skin was processed into small chips that were cultured in vitro and subjected to inverted phase contrast microscopic and scanning electron microscopic observation. The fibroblasts swam out of the skin chips and they increased in number rapidly and became confluenced. The cells exhibited squamous configuration, possessing arboreal bifurcations and forming multi-layer structure. The fibroblasts then excreted numerous minute granules, heaping up on and around the cells. Henceforth emerged on the cell surface fine needle-like crystals, that agglomerated with the granules to form nodules. The fibroblasts orientated themselves in a radiating pattern around the large nodules. Neighbouring nodules could be linked up into trabecular structure. Histochemical study of both the nodules and the trabecular structure with specific new bone labeller (Tetracycline and Alizarin red S) revealed positive reaction, denoting that the nodules and the trabecular structure produced by the fibroblasts were bone tissues. These results pointed out clearly to the osteogenic potential of the dermal fibroblasts.

Animals↗
PubMed1999

Enhanced retention of glass-ionomer sealant by enamel etching: a microleakage and scanning electron microscopic study.

OBJECTIVE: A microleakage study and a scanning electron microscopic investigation were conducted to test whether etching of enamel would improve adhesion of glass-ionomer cement sealants to fissure enamel. METHOD AND MATERIALS: Forty-eight extracted human molars and premolars were divided into 2 equal groups, and their crowns were cleaned with pumice. In group 1 enamel was etched for 45 seconds with 37% phosphoric acid. In group 2, enamel was not etched. Glass-ionomer sealant was applied to all 48 teeth. Twenty teeth from each group were thermocycled in water (120 cycles between 0 degree C and 56 degrees C) and stained with 0.5% methylene blue solution. The remaining 4 teeth from each group served as a control for the scanning electron microscopic evaluation. Twelve teeth from each group were cut into 5 sections, and 12 were cleaved into 3 sections in a buccolingual direction. RESULTS: Statistically significant differences in amounts of microleakage were found between group 1 and group 2. Minimal microleakage was detected in 90% of the etched teeth, whereas extensive microleakage was observed in 85% of nonetched teeth. The scanning electron microscopic evaluation correlated positively with the microleakage observations. The etched teeth revealed a cohesive failure within the sealant material, while the nonetched teeth demonstrated an adhesive failure at the sealant-enamel interface. Observation of the nonthermocycled teeth confirmed those findings. CONCLUSION: Results suggested that etching prior to application enhances the bonding of glass-ionomer sealant to fissure enamel.

Acid Etching, Dental↗
PubMed1993

Origin of bone hyperplasia in osteoarthritic femoral head. Tetracycline labelling and scanning electron microscopic study.

Total hip replacement was carried out in 7 patients with advanced osteoarthritis of the hip joint. The patients were given tetracycline orally before operation to label the newly formed bone tissues. The excised femoral heads were processed into undecalcified sections, which were subjected to both fluorescence microscopic and scanning electron microscopic (SEM) observation. Band-shaped golden fluorescence was detected along the trabeculae, reflecting newly formed bone tissues by the cambium layer of the periosteum. In the intertrabecular space, reticular and spherical golden fluorescence was detected, implying newly formed bone tissues by the marrow stromal cells. Under SEM, both reticular and spherical new bone tissues were discovered in the inter-trabecular space as mentioned above. There were two forms of reticular new bone tissues, a diffuse form and a tape-shaped new bone tissues. The diffuse bone tissues grew and expanded and eventually studded the inter-trabecular space. The tape shaped tissues, which were first deposited on the trabecular arch surface, increased in amount and then woven into thin and dense tapes of the reticulum. These tapes contacted in an end-to-end fashion, and appeared to shuttle back and forth through the trabecular arches, forming new secondary arch structures. The spherical new bone tissues were deposited on the surface of the trabecular arch structures and gradually packed the intertrabecular space. These new bone tissues were contributed to hyperplasia in the osteoarthritic femoral head.

Femur Head↗
PubMed1980

Dentin dysplasia type I: a scanning electron microscopic analysis of the primary dentition.

Dentin dysplasia type I (DD-I) is a rare autosomal dominant disorder which affects both the deciduous and permanent dentitions. The affected deciduous and permanent teeth have short conical roots with sharp, apical constrictions and frequently periapical radiolucencies in the absence of caries. Apical to a thin layer of normal coronal dentin are large, calcified, dentin masses which nearly obliterate the pulp chamber and canals. Presented here are light microscopic and scanning electron microscopic observations of deciduous teeth from three unrelated persons with the disorder. In general, the deciduous teeth had (1) normal enamel, (2) a thin layer of normal dentin adjacent to the dentinoenamel junction, (3) a crescent-shaped pulpal remnant below the normal dentin, (4) dysplastic dentin masses (ranging from atubular to a few small tubules) between which are spaces presumed to previously have contained smaller remnants of the original mesenchymal dental papilla, and (5) root dentin, which is dysplastic throughout. The SEM-defined phenotype, however, was noticeably variable among all three persons. Based on the current concepts of tooth morphogenesis, it is most likely that the abnormal root morphology of DD-I teeth is secondary to the abnormal differentiation and/or function of the ectomesenchymally derived odontoblasts.

Adult↗
PubMed2003

Comparative study of depth and lateral distributions of electron excitation between scanning ion and scanning electron microscopes.

In order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM), the depth and lateral distributions of secondary electrons escaped from surfaces of 17 metals with atomic numbers, Z2, of 4-79 were calculated for bombardment with 30 keV Ga ions and for 10 keV electrons. For both projectiles, the excitation depth generally decreased with increasing Z2, while showing the same periodic change as the secondary-electron yield. However, an opposite trend in Z2 dependence between the Ga ion and electron bombardments was calculated with the lateral distribution of secondary electrons escaped from the surface. Except for low Z2 metals, the lateral distribution, which is much narrower for 30 keV Ga ions than for 10 keV electrons, indicates that the spatial resolution of the secondary-electron images is better for SIM than for SEM, if zero-sized probe beams are assumed. Furthermore, the present calculation reveals important effects of electron excitation by recoiled material atoms and reflected electrons on the lateral distribution, as well as the secondary-electron yield, for the Ga ion and electron bombardments, respectively.

Journal Article↗
PubMed2005

rRNA sequence-based scanning electron microscopic detection of bacteria.

A new scanning electron microscopic method was developed for gaining both phylogenetic and morphological information about target microbes using in situ hybridization with rRNA-targeted oligonucleotide probes (SEM-ISH). Target cells were hybridized with oligonucleotide probes after gold labeling. Gold enhancement was used for amplification of probe signals from hybridized cells. The hybridized cells released a strong backscatter electron signal due to accumulation of gold atoms inside cells. SEM-ISH was applied to analyze bacterial community composition in freshwater samples, and bacterial cell counts determined by SEM-ISH with rRNA-targeted probes for major phyla within the domain Bacteria were highly correlated to those by fluorescent in situ hybridization (FISH). The bacterial composition on surface of river sediment particles before and after cell dispersion treatment by sonication was successfully revealed by SEM-ISH. Direct enumeration of bacterial cells on the surface of sonicated sediment particles by SEM-ISH demonstrated that members of Cytophaga-Flavobacterium existed tightly on the surface of particles. SEM-ISH allows defining the number and distribution of phylogenetically defined cells adherent to material surfaces, which is difficult in FISH, and it gives new insight into electron microscopic studies of microorganisms in their natural environment.

Bacteria↗
PubMed1968

Use of the scanning electron microscope for viewing bacteria in soil.

Scanning electron microscopy was used for viewing Bacillus cereus and Staphylococcus aureus in three different soils. Both organisms were detected in the test soils at an approximate concentration of 10(7) cells per gram of soil; theoretically, the minimal number of microorganisms required for detection with the scanning electron microscope technique was between 10(7) and 10(10) cells per gram of soil. Because the concentration of cells was critical, the use of scanning electron microscopy as an extraterrestrial life detection instrument would be limited with soils containing more than 10(7) bacteria per gram of soil.

Bacillus cereus↗
PubMed1979

Transmission and scanning electron microscopic studies of rhinoscleroma.

Using both types of electron microscope, combined transmission and scanning electron microscopic studies were done on 6 patients with rhinoscleroma. The present work suggests the possibility of two types of organisms causing the disease: one type--being in the majority--was a rod-shaped bacillus measuring about 3 micrometers; the other type was a short, stout bacillus with terminal spiral cilia. The ultrastructure of these bacilli has been described. The advantages and limitations of each type of electron microscopy in the investigation of rhinoscleroma have been discussed.

Humans↗