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PubMed1977

Detection of neoplastic and preneoplastic urothelia by combined scanning and transmission electron microscopy of urinary surface of human and rat bladders.

Scanning and transmission electron microscopy reveal distinct differences between the appearance of the luminal surface membrane of normal urothelium and those of transitional cell tumours of both human and rat bladder. The luminal surface membrane of the preneoplastic rat urothelium shows features similar to those seen in the fully developed tumour. In human tumour-bearing bladders the urothelium away from the transitional cell tumour is not recognizable as being preneoplastic by light microscopy. However, by scanning or transmission electron microscopy, the luminal membrane in some areas shows changes identical to those in the preneoplastic rat bladder. These observations are in accordance with the clinical behaviour of the urothelium in patients with vesical transitional cell tumours which tend to recur in disparate site. We suggest that scanning electron microscopy of the bladder urothelium away from the tumour may be of prognostic value for indicating the subsequent biological behaviour of the urothelium.

Animals↗
PubMedDate not supplied

[Comparative light and scanning electron microscopy studies of the morphologic structure of ligament insertions into the bone].

The microstructure of the osseous ligament insertion was studied by light microscopy and scanning electron microscopy using the insertion of the membrana interossea antebrachii as an example. The scanning electron microscopical findings of specimens which had been prepared by freeze-fracturing confirm the typical 4-zone-structure of the osseous ligament insertion. The findings emphasize the functional importance of both zones of unmineralized and mineralized fibrous cartilage, which represent an effective shock absorbing system for the collagenous structures of the osseous ligament insertion.

Cartilage↗
PubMed1985

Scanning electron microscopy in retinal research.

The literature on scanning electron microscopy (SEM) pertaining to the retina has been surveyed and described. The first two papers on SEM and retina appeared in 1969. Most of the earlier studies concentrated on descriptions [by SEM alone, or with light microscopy (LM) and transmission electron microscopy (TEM)] of the appearance of various retinae and retinal cells [fish, newt, primates, rodents and rabbits, bullfrog]; or embryology of the chick retina. Two papers dealt with retinal disease. In all there were 25 papers in SEM/retinal research before and in 1974. Since 1975 there have been 111 papers which have used SEM in retinal research in very many different fields and in diverse ways, viz: the morphology of the retina, specific retinal cells, and the retinal vessels; embryology; labelling of retinal cells with surface markers; naturally occurring and experimentally-induced retinal disease; the effects of light, including lasers and photocoagulation, and other radiation on the retina, and phagocytosis and the retinal pigment epithelium (RPE). There have also been a number of papers concerned with techniques for SEM, applicable to retinal research, and several review articles. SEM has proven to be a very valuable adjunct to TEM in retinal research and it has become an accepted and almost routine way of extending and enhancing reports on retinal research. Properly used, SEM provides a laconic way of presenting information that might otherwise require many serial sections and long explanations.

Animals↗
PubMed1998

Macromolecular structure determination by electron microscopy: new advances and recent results.

Electron microscopy is undergoing a mini-renaissance, as a number of biological systems are yielding to higher resolution analysis as a result of advances in instrumentation, specimen preparation and image-processing technology. The atomic structure of tubulin has now been solved, crucial elements of secondary structure have recently been revealed in several membrane proteins (rhodopsin, gap junctions, aquaporin, and Ca2+ and H+ ATPases) and in a virus particle, and macromolecular complexes are being seen in increasingly fine detail. This growth has been enhanced further by the ability to combine structures of macromolecular complexes derived by electron microscopy with X-ray structures of their components, in order to reconstruct molecular machines and large multiprotein complexes in immense detail.

Crystallization↗
PubMed1982

Bladder mucin: a scanning electron microscopy study in experimental cystitis.

Scanning electron microscopy has been used to assess surface mucin changes following an induced Escherichia coli urinary tract infection in the rat bladder. The principal changes seen following bacterial challenge were bacterial adherence to the urothelium, swelling of epithelial folds, disruption of the mucin layer, and increased adherence of bacteria to the sub-surface epithelium. The bladder mucin before infection appeared as an even, whitish, viscous layer which covered epithelial cells and cell junctions. Bacteria appeared to become enmeshed in mucin strands after infection and this process may facilitate bacterial washout from the bladder. A recovery phase showed reversal of the scanning electron microscopy changes. These findings support other studies in suggesting that mucin may play a role in protecting the bladder from invading and adhering bacteria.

Animals↗
PubMedDate not supplied

Pathology of rotavirus infection in suckling mice: A study by conventional histology, immunofluorescence, ultrathin sections, and scanning electron microscopy.

Pathologic changes induced in the small intestine of suckling mice by rotavirus infection were studied by conventional histology, immunofluorescence, scanning electron microscopy, and electron microscopy of ultrathin sections. Infection could be detected within 24 hours in a few mice, but after 2 days it was well established. Swollen, often vacuolated infected cells were found on the sides and tips of villi from which they rapidly became detached; microvilli showed variable irregularity. Immature enterocytes from crypts replaced lost infected cells. By the tenth day very few infected cells could still be found. Both tubular structures and spherical particles occurred in the infected cells. Only tubular structures were found in nuclei.

Animals↗
PubMed2003

Thin dielectric film thickness determination by advanced transmission electron microscopy.

High-resolution transmission electron microscopy (HR-TEM) has been used as the ultimate method of thickness measurement for thin films. The appearance of phase contrast interference patterns in HR-TEM images has long been confused as the appearance of a crystal lattice by nonspecialists. Relatively easy to interpret crystal lattice images are now directly observed with the introduction of annular dark-field detectors for scanning TEM (STEM). With the recent development of reliable lattice image processing software that creates crystal structure images from phase contrast data, HR-TEM can also provide crystal lattice images. The resolution of both methods has been steadily improved reaching now into the sub-Angstrom region. Improvements in electron lens and image analysis software are increasing the spatial resolution of both methods. Optimum resolution for STEM requires that the probe beam be highly localized. In STEM, beam localization is enhanced by selection of the correct aperture. When STEM measurement is done using a highly localized probe beam, HR-TEM and STEM measurement of the thickness of silicon oxynitride films agree within experimental error. In this article, the optimum conditions for HR-TEM and STEM measurement are discussed along with a method for repeatable film thickness determination. The impact of sample thickness is also discussed. The key result in this article is the proposal of a reproducible method for film thickness determination.

Image Processing, Computer-Assisted↗
PubMed1969

Measurement of thickness within sections by quantitative electron microscopy.

To apply the method of quantitative electron microscopy to the measurement of mass in thin sections, the thickness of the section at or very near the structure to be studied must be known. Dowex anion exchange resin AG 1 x 2, stained with phosphotungstic acid (PTA) at pH 6.4, was used as a thickness standard which could be embedded and sectioned. The sectioned PTA-Dowex appeared uniformly stained and exhibited suitable electron opacity. The stoichiometry of the reaction between PTA and the Dowex resin was measured by three independent methods based on gravimetric, colorimetric, and nitrogen determinations whose results showed close agreement. From the PTA uptake, the density of the stained spheres was calculated. Mass of a defined area of PTA-Dowex was measured by quantitative electron microscopy, and from this mass and density, the volume and then the thickness were calculated. The values for thickness were compared to those obtained by interference microscopy on the embedding medium alone in the same sections.

Colorimetry↗
PubMed1990

Imaging cytoskeleton--mitochondrial membrane attachments by embedment-free electron microscopy of saponin-extracted cells.

Embedment-free electron microscopy images the cytoskeleton and nuclear matrix, which are very difficult to visualize in conventional electron micrographs. However, to be effective, cell structures must be depleted of soluble proteins, which otherwise shroud cell architecture. Nonionic detergents effect this extraction, releasing soluble proteins but also destroying all membranes. Saponin can permeabilize plasma membranes, releasing soluble proteins while preserving many cytoplasmic membranes. Stereoscopic electron microscopy of resinless sections shows the many connections of the cytoskeleton to mitochondrial membranes.

Animals↗
PubMed2003

Electron microscopy for rapid diagnosis of infectious agents in emergent situations.

Diagnostic electron microscopy has two advantages over enzyme-linked immunosorbent assay and nucleic acid amplification tests. After a simple and fast negative stain preparation, the undirected, "open view" of electron microscopy allows rapid morphologic identification and differential diagnosis of different agents contained in the specimen. Details for efficient sample collection, preparation, and particle enrichment are given. Applications of diagnostic electron microscopy in clinically or epidemiologically critical situations as well as in bioterrorist events are discussed. Electron microscopy can be applied to many body samples and can also hasten routine cell culture diagnosis. To exploit the potential of diagnostic electron microscopy fully, it should be quality controlled, applied as a frontline method, and be coordinated and run in parallel with other diagnostic techniques.

Communicable Diseases, Emerging↗
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↗
PubMed1981

Cell cycle-related morphological changes of feline lymphoid cells as revealed by electron microscopy.

The aim of this study was to correlate morphological changes in cells to known phases of the cell cycle. For this purpose, feline lymphoblastoid cells (FL74) chronically infected with feline leukemia virus were synchronized and examined by scanning and transmission electron microscopy. Scanning electron microscopy revealed that the cell surface underwent distinct changes which were found to be cell cycle specific. Morphological changes shown by transmission electron microscopy were used as ultrastructural markers to confirm the findings made by scanning electron microscopy relating to the various phases of the cell cycle. The results of these experiments suggest that the presence of morphologically mixed populations of cells in many lymphoproliferative disorders, which had been described previously, may be explained by normal cell cycle-dependent variations.

Animals↗
PubMed1998

Rigid gas permeable contact lenses surface roughness examined by interferential shifting phase and scanning electron microscopies.

The anterior surface roughness of seven factory new rigid gas permeable (RGP) contact lenses has been studied by interferential shifting phase microscopy (ISPM) and scanning electron microscopy (SEM). Five lenses were fluorsilicone acrylate and two lenses were silicone acrylate. Their material Dk ranged from 14 to 210. ISPM is shown to be a reliable and non-destructive method to observe and measure the relief of the contact lens surface. Moreover, profile and contour data are easily stored for further quantitative studies. ISPM contour patterns of the studied lenses are qualitatively compared with those obtained by SEM for the same lenses. Results point out that ISPM gives similar accuracy but it is non-destructive and cheaper than SEM. Moreover, the quantitative study of surface roughness suggests that there is a relationship between surface roughness and Dk of the lens material: surface roughness increases with Dk and allows to distinguish between lenses with low, medium and high Dk.

Contact Lenses↗
PubMed1991

High-voltage electron microscopy of normal human cornea.

Conventional transmission electron microscopy (CTEM) was compared with high-voltage electron microscopy (HVEM) on 11 normal human corneas (age range, 30 weeks of gestation to 92 yr). Epithelial anchoring fibrils were noted between the basal epithelial cells and Bowman's layer (BL) as previously reported. Parallel pairs of fibers, 27.5 nm in diameter, were observed crossing into the anterior stromal lamellae from BL; their termination sites, however, were not identified. The lateral termination of BL was marked by the presence of a keratocyte lying directly below the end of the multilaminar basal lamina. In this region, BL tapered and became interwoven with the scleral collagen fibrils in the substantia propria. The HVEM accentuated the orthogonal relationship of collagen bundles apparently emerging from the stromal keratocytes. The posterior corneal stroma appeared to be attached to the anterior surface of Descemet's membrane (DM) by fibers 22.3 nm in diameter that were associated frequently with a dense amorphous material. In the periphery, DM tapered to a thin strand, 0.5 microns in thickness, containing cable-like strands of banded collagen. The posterior nonbanded portion continued laterally and anteriorly in a series of folds between the fibrous collagen sheets of the anterior trabecular meshwork. In addition, HVEM enhanced the visibility of extracellular matrix interactions in the lateral terminations of BL and DM, attachment fibers from BL to the stroma and from the stroma to DM, and keratocyte and collagen fiber orientations not seen easily by CTEM.

Adolescent↗
PubMed1977

Pseudoexfoliative disease of the lens: a study in electron microscopy and histochemistry.

The anterior lens capsule in pseudoexfoliative (PE) disease has been investigated with scanning electron microscopy and transmission electron microscopy. It shows several distinct zones which correlate with those seen clinically. True exfoliation of the anterior lens capsule is shown as an integral pathologic feature of PE disease. PE fibrils are mixed with various degraded cell products, including organelles, of which uveal pigment granules are the most frequent. Sheets of degenerating iris pigment epithelium as well as individual cells are often firmly adherent to the pre-equatorial lens capsule and zonules. PE fibrils on the capsule are 35 to 40 nm in width, often showing several subunit filaments about 10 nm wide. PF filaments forming vertical bundles in the pre-equatorial capsule are 10 nm wide, but show little tendency to aggregate laterally. Histochemical and ultrastructural properties of both types of PE fibril and those of the capsular inclusion suggest that they are closely related fibrillar proteins. PE fibrils share some of the characteristics of amyloid but are not identical substances. Nevertheless, a similar mechanism of synthesis is suggested. The participation of non-lenticular sites in the formation of PE fibrils is not precluded by this hypothesis.

Aged↗
PubMed1976

Interaction of rabbit sperm and egg. Examination of the same cryofractured specimens with scanning and transmission electron microscopy.

Rabbit ova fertilized in vitro were prepared for scanning electron microscopy by ethanol-cryofracturing and critical-point drying methods and were also embedded and sectioned for transmission electron microscopy. Study of a region of interaction between sperm and zona pellucida with scanning electron microscopy reveals the latter to be composed of a complex network of fibers interspersed with numerous pores. Transmission electron microscopy of the same region reveals a "typical" homogeneous composition of the zona pellucida. Ultrastructural observations of thin sections passing through the region of sperm-egg interactions or through other regions of the ovum or its investments reveals very little methodological distortion of the various intracellular organelles or matrix. Application of the procedures described provides not only an elucidation of surface detail but also reveals intracellular cytoplasmic information about the same specimen during in vitro fertilization.

Animals↗
PubMed2004

Investigation of quantitative secondary electron imaging of semiconducting polymer materials using environmental scanning electron microscopy.

The development of environmental scanning electron microscopy has opened the way for the examination of a wide variety of new sample types that were previously inaccessible to conventional scanning electron microscope techniques. With the advent of such a new methodology comes also the potential for new contrast mechanisms. We investigated the use of environmental scanning electron microscopy on semiconducting organic polymer materials. We observed contrast from these materials in secondary electron images, this contrast being attributed to differences in electron yield due to the polymer's electronic structure. Further study of these materials, and specifically the influence of film thickness on signal, has indicated a significant effect as the secondary electrons move through the sample. Systematic studies such as these are needed for a full understanding of the relationship between electronic properties and signal and, hence, the ability to probe structure-property relationships in greater depth.

Environment↗
PubMed2003

Recent advances in electron imaging, image interpretation and applications: environmental scanning electron microscopy.

One of the latest developments in electron microscopy is the environmental scanning electron microscope (ESEM), which enables soft, moist and/or electrically insulating materials to be viewed without pre-treatment, unlike conventional scanning electron microscopy, in which specimens must be solid, dry and usually electrically conductive. Such an advance has significant implications for studies of the 'native' surfaces of specimens including rocks and minerals, polymers, biological tissues and cells, food and pharmaceutical products, precious artefacts and forensic material, for example. Previous types of electron microscopes made scientists think carefully about the physics of electron-beam interactions with specimens and, hence, the interpretation of images. We now face additional factors influencing the emission and detection of electron signals, unique to the imaging of specimens in the partial vacuum of an ESEM. Just as importantly, we must consider the thermodynamic and kinetic stability of specimens, as appropriate, and explore the possibilities for new applications, particularly those of a dynamic nature. This paper briefly describes some of the issues involved and reviews the current state of understanding.

Environmental Monitoring↗