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PubMed1981

Electron microscopy in surgical pathology: a selective review.

The high resolution provided by electron microscopy can contribute to histomorphological diagnosis by allowing the detection of structures which are invisible to the light microscope. These structures include characteristic nuclear or cytoplasmic contours, intercellular attachments and intracellular components. The recognition of such features may allow specific diagnosis in lesions which cannot be precisely categorized by light microscopy. Electron microscopy is particularly useful for the diagnosis of neoplasms. This review describes some of the characteristic morphological features which can be demonstrated in neoplastic cells by electron microscopy and briefly considers several areas where the technique is of special value. Electron microscopy is now an integral part of the diagnostic process in surgical pathology and can be regarded as a routine technique rather than a special procedure to be delegated to others.

Adenocarcinoma↗

PubMed1982

Aortic endothelium of alloxan diabetic rabbits: a quantitative study using scanning electron microscopy.

Scanning electron microscope studies of the aorta and other major arteries have been performed in alloxan-induced diabetic rabbits. After 5 weeks, a variety of structural abnormalities of the endothelial lining were detected including a significant increase in the number of argyrophilic cells and an increased number of craters or openings in the endothelial junctional region. Evidence of more extensive micro-damage was present after 5 months duration of diabetes. These zones with structural changes in the endothelial lining of major vessels seem to be areas of high predilection to atherosclerosis in diabetes.

Animals↗

PubMed1991

Morphologic changes in the human amnion epithelium that accompany labor as seen with scanning and transmission electron microscopy.

Scanning and transmission electron microscopy were used to assess the influence of normal, active labor on the ultrastructure of the human amnion epithelial membrane. Amnion membranes (reflected and placental portions) were obtained from patients either in active labor who were delivered vaginally or by cesarean section after 6 to 12 hours of labor or from patients who underwent elective cesarean section before clinical signs of overt labor. Scanning electron microscopy revealed that reflected amnion membranes that were obtained from patients who were not in labor consisted of a uniform single layer of epithelial cells with numerous microvilli on the apical surface and closely associated cellular borders. In contrast, amnion membranes that were obtained from patients who were in labor consisted of a single layer of epithelial cells, which was interrupted by wide intercellular gaps and extracellular extrusions. Transmission electron microscopy showed that intercellular junctions tended to be less complex in patients who were in labor versus patients who were not in labor. Although lipid droplets were prevalent in both patient groups, specimens that were obtained from patients who were in labor had more lipid droplets per cell than specimens from patients who were not in labor. These results support the theory that the complex biochemical events that culminate in parturition are accompanied and/or preceded by demonstrable morphologic changes in the amnion membrane.

Amnion↗

PubMed2004

Viruses and the development of quantitative biological electron microscopy.

The electron microscope has become an important tool for determining the structure of biological materials of all kinds. Many technical advances in specimen preparation and in sophisticated methods of image analysis, initially based on optical systems but latterly on computer processing, have contributed to the development of the subject. Viruses of various kinds have often provided a convenient and appropriate test specimen. This paper describes the major technical advances and shows how viruses have had an important role in most of the developments.

Electronic Data Processing↗

PubMed1990

New sensitive light microscopical detection of colloidal gold on ultrathin sections by reflection contrast microscopy. Combination of reflection contrast and electron microscopy in post-embedding immunogold histochemistry.

One simple post-embedding method for combined light- and electron microscopy is presented. Different types of antigens in normal rat and mouse kidneys as well as in tissues from cases of experimental induced nephritis were stained after Lowicryl K4M embedding by an immunogold (silver) method. The (silver-enhanced) gold particles were visualized by light microscopy, e.g. bright-field (BFM)- and reflection contrast (RCM) microscopy, as well as by electron microscopy. The potentials of RCM visualization in this field were investigated, resulting in the successful detection of colloidal gold (15 nm) particles, or silver enhanced gold particles, on ultrathin sections. Furthermore, an increased detection sensitivity of RCM compared with BFM together with an increase in the sensitivity of the immunostaining by RCM visualization was found. The different ways to use RCM, alone or in combination with bright-field- or phase contrast microscopy for visualization of plastic sections varying in thickness, type of plastic and staining, are discussed.

Animals↗

PubMed1994

Understanding the neostriatal microcircuitry: high-voltage electron microscopy.

High voltage electron microscopy (HVEM) and HVEM tomography of selectively stained cell processes in the neostriatum have offered an alternative to serial thin section reconstruction for accurate 3-D visualization and measurement of axons, dendrites, and dendritic spines. Tissue preparation is simple and rapid, allowing examination of large numbers of specimens required for quantitation of neuronal morphology. The resolution of the images exceeds that available from any light microscopic technique and is appropriate for measurement of the finest axons and dendritic spine necks. HVEM tomography allows the direct measurement of dendritic surface area, required for computational modeling of synaptic integration.

Humans↗

PubMed1987

Detection of adenovirus types 40 and 41 in stool specimens by immune electron microscopy.

An immune electron microscope (IEM) test was developed that allowed the direct detection of adenovirus type 40 (ad 40) or ad 41 in stools specimens. The polyclonal rabbit antisera used differentiated ad 40 and 41 from other ad serotypes but not from each other. The method was evaluated in a 13 month prospective study of stools from children with gastroenteritis. Seventy-two specimens found to contain ad by conventional electron microscope screening were retested by IEM. Results were typically obtained within 2 hr and showed that 55 (76%) viruses typed as ad 40/41. No ads were recovered from conventional virus isolation attempts on these specimens. Additionally, 39 of these 55 viruses were tested by restriction endonuclease analysis (REA) after growth in 293 cells, and results showed that all produced digest patterns typical of ad 40 (seven cases) or ad 41 (32 cases). Twenty-four percent (17/72) of viruses could not be typed by IEM; 9/17 (53%) yielded ads [ad 1 (1), ad 2 (4), ad 5 (1), ad 6 (1), ad 7 (2)] in routine culture, whereas REA identified the other eight as ad 2 (6), ad 1 (1), and ad 41 (1). The concordance between IEM and the reference methods was therefore 100% specificity and 97.5% sensitivity. The method described allows the clinically useful diagnosis of ad 40/41 infection to be rapidly made and will be a particularly useful technique in laboratories screening faeces by electron microscopy.

Adenoviridae Infections↗

PubMedDate not supplied

An improved specimen loader for cryo-scanning electron microscopy.

Cryo-electron microscopy of cryofixed samples is a well-established and accepted technique for imaging liquid-containing specimens without removing water and other volatile components. There are many steps between cryofixation and cryo-observation in the microscope, during which the sample and sample holder need to be handled. One such major step is the loading of the specimen onto the sample holder and the fixing of the sample holder onto the transfer mechanism. During this handling, the specimen is often exposed (mostly inadvertently) to moisture in the atmosphere, which results in frost deposition. The new specimen loader described here is designed to overcome the traditional tedious handling and to achieve ease in specimen loading. The modifications made are mainly towards allowing movement of the liquid freon cup, eliminating the need for a lock-screw and improving the shape of the stage holder, which makes the mounting of the specimen holder easy, thereby permitting smooth specimen loading without too much handling and with consequent reduced frost deposition.

Cryoelectron Microscopy↗

PubMedDate not supplied

Visualization of a ternary complex of the Escherichia coli Phe-tRNA(Phe) and Tu.GTP from Thermus thermophilus by scanning transmission electron microscopy.

Scanning transmission electron microscopy (STEM) was used to visualize formation of a ternary complex between the T. thermophilus elongation factor (EF) Tu.GTP and the Escherichia coli Phe-tRNA(Phe) labeled with an undecagold (Au11) cluster at minor nucleotide 3-(3-amino-3-carboxypropyl) uridine at position 47. The ternary complex was further characterized by the molecular mass and radius of gyration calculated from the mass distribution within the individual particles. Under conditions used for STEM imaging, the ternary complex is formed between Au11-labeled Phe-tRNA(Phe) and Tu.GTP in a yield up to 25%. The stoichiometry of EF-Tu.GTP to aminoacyl-tRNA (aa-tRNA) in the EF-Tu.GTP.aa-tRNA complex is 1:1, in agreement with the established view of the protein biosynthesis mechanism. The ternary complex is also formed, although to a lower extent, with GTP analogues (GMPPCP and GMPPNP, respectively), but not with Tu.GDP and nonaminoacylated tRNA(Phe) with Tu.GTP.

Escherichia coli↗

PubMed1982

Host-parasite interface of the fluke Collyriclum faba (Bremser in Schmalz, 1831) as revealed by light and electron microscopy.

Light and electron microscopy of Collyriclum faba reveals that the dorsal tegument is highly convoluted, containing regular groups of between one and five spines. The thinner ventral covering has a less spiny surface with shallow infoldings. The lining of the capsule is characterized by numerous layers of collagen reflecting a strong cellular response by the host.

Animals↗

PubMed1989

Diabetic choroidal and iris vasculature scanning electron microscopy findings.

Scanning Electron Microscopy (SEM) was used to study vascular casts of twenty-four autopsy eyes taken from patients with long-standing insulin-dependent Diabetes Mellitus. These casts were compared to casts of ten 'normal' autopsy eyes from patients without a history of diabetes or other vascular disease. The SEM findings in the choroidal vessels of the diabetic eyes included: increased tortuosity, focal vascular dilations and narrowings, hypercellularity, vascular loops and microaneurysm formation, 'drop-out' of choriocapillaries, and sinus-like structure formation between choroidal lobules in the equatorial area. In the iris, neovascularization was evident in the vascular casts in cases with clinically recognized rubeosis iridis. These findings indicate that there is significant involvement of the uveal tract in diabetic eyes. The present study strongly supports the Hidayat and Fine light microscopic observation that the diabetic choroid demonstrates significant vascular changes (e.g. narrowed vessels with possible 'drop-out' of capillaries and neovascularization). Changes in the diabetic choroid, especially in the choriocapillaris, may be a contributing factor in diabetic retinopathy, resulting in decreased oxygenation of the outer layer of the retina. Short reviews and updated information of diabetic eye disease provide some additional insights into the vascular problems in the eye.

Adult↗

PubMed1997

The anterior central nervous system of male Onchocerca volvulus (Nematoda:Filarioidea) as a target for chemotherapy: results of an electron microscopy study.

An electron microscopy study was performed to evaluate the feasibility of the use of the anterior nerve ring of male Onchocerca volvulus for the assessment of early drug effects. Worms were exposed to new and known compounds at reasonable concentrations of 1 microM and less for 6, 12, 18, and 36 h in an established in vitro system. The anterior end of the filariae up to a length of 1 mm was examined and the morphological findings were compared with motility and reduction of a tetrazolium sat to formazan by live but not dead worms. The nerve fibers were more susceptible to the chemotherapeutic intervention then the other tissues in the anteriormost part of the worms. The alterations depended on the duration of exposure and the chemical nature of the compounds used. Morphological changes in the nervous tissue and the inhibition of motility and formazan production corresponded well for the arsenical mel w, used as an active standard, two pyrimidinyl-guanidines (PD 105482 and PD 105666), and an imidazolinylhydrazone (WR 251993).

Animals↗

PubMed2003

SEM study of water activity and temperature effects on the initial growth of Aspergillus ochraceus, Alternaria alternata and Fusarium verticillioides on maize grain. Scanning electron microscopy.

A scanning electron microscopy (SEM) study of the effect of water activity (a(w)), temperature and fungal interactions on the very early phases of Aspergillus ochraceus, Alternaria alternata and Fusarium verticillioides development on maize grains was carried out. Germination and growth of individual fungal strains were assayed at 0.92, 0.95 and 0.98 a(w), and 20 and 30 degrees C. Hyphal lengths were measured on micrographs taken by SEM at different periods of incubation. A. alternata had the highest linear growth at 0.98 a(w), and was the only species able to grow under all conditions tested, whereas A. ochraceus was not able to germinate at 0.92 a(w) at any temperature assayed. F. verticillioides demonstrated a different behaviour depending on growth temperature. Fungal interactions were studied at 0.95a(w) and 30 degrees C. A. ochraceus germination was inhibited when it was co-inoculated with one or two of the other species. A. alternata showed an increased growth rate when growing together with the other fungi, whereas growth of F. verticillioides was significantly inhibited when paired with A. ochraceus.

Alternaria↗

PubMed2005

Characterization of humic substances by environmental scanning electron microscopy.

Environmental scanning electron microscopy (ESEM) is a new technique capable of imaging micron and submicron particles. Here, we have applied it to image and quantify natural aquatic organic matter (standard Suwannee River humic acid, SRHA). Uniquely, we have observed the humic aggregate structures as a function of humidity and pH. Large aggregates of tens of micrometers were observed as the dominant material under all conditions, although much smaller material was also observed. Fractal dimensions (D) were calculated between 1.48 and 1.70, although these values were not statistically different under conditions of low humidity. However, D values calculated at high humidities (85%) during the rehydration phase were significantly lower (1.48+/-0.01) than in the initial dehydration phase (1.69+/-0.01). This hysteresis indicated that full rehydration of the HS was either kinetically slow or irreversible after dehydration. Fractal analysis of ESEM images was also performed to probe the change in aggregate structure as a function of pH. Minimum values were calculated at neutral pHs, rising by 0.1-0.2 at both high and low pHs because of a combination of the physical chemistry of HS and the impacts of the drying regime within the ESEM. Thus, ESEM was an important complementary technique to other analytical methods. At present, ESEM cannot be used to image nonperturbed natural samples. However, the method is an ideal method for probing the changes in colloid structure as function of hydration state and has the potential to perform fully quantitative and nonperturbing analysis of colloidal structure.

Chemistry Techniques, Analytical↗

PubMed1994

The zona reaction in human oocytes as seen with scanning electron microscopy.

Using scanning electron microscopy we found differences in the fine structure of the zona pellucida between unfertilized and fertilized human pronuclear stage oocytes in an in-vitro fertilization programme. In unfertilized oocytes, the zona pellucida appeared porous, comprising a large number of ring-shaped structures, called hoops, randomly superimposed in several layers. Superficial pores had a mean diameter of 4 microns, with the diameter decreasing in more inner lying pores. In fertilized oocytes, the zona pellucida was compact; the hoops appeared to melt and the pores to be obliterated by an amorphous material emerging from the inner zona. The micrographs provide ultrastructural evidence of the zona reaction in human oocytes and give insights into the morphological and mechanical aspects of the polyspermy-blocking mechanism in humans.

Female↗

PubMed1983

Antigenic cross-reactions between woodchuck hepatitis virus and human hepatitis B virus shown by immune electron microscopy.

Using immune electron microscopy (IEM), low-level cross-reactions could be demonstrated between the surface antigens of hepatitis B and woodchuck hepatitis. However, immune complex formation was greatly enhanced by pre-exposure of the antigens to 0.5% deoxycholate. Cross-reaction between the core antigens and e antigens of both viruses was also confirmed by IEM as well as radioimmunoassay. It appears that the woodchuck sera used in this study may well contain an anti-immunoglobulin akin to rheumatoid factor.

Animals↗

PubMed1987

The morphology of human immunodeficiency virus particles by negative staining electron microscopy.

Negative staining electron microscopy was used to examine culture fluids from the H9/HTLV-III cell line after concentration by centrifugation. Characteristic retrovirus-like particles bearing distinctive envelope projections were seen. The virion envelope was frequently extended in the form of a bleb or a tail. These particles were morphologically virtually indistinguishable from similar preparations of Friend murine leukaemia virus. H9/HTLV-III culture fluids contained, in addition, numerous comet-shaped particles with a dense head and flared tail. These particles were clumped by the addition of anti-HTLV-III-positive serum suggesting that they may represent intermediate forms of the virus.

Cell Line↗

PubMed1989

The morphology of simian immunodeficiency virus as shown by negative staining electron microscopy.

Negative staining electron microscopy was used to study sucrose gradient-purified preparations of the simian immunodeficiency virus (SIVmac251). Both isolated and aggregated virus particles were observed together with some free-lying virus cores. The cores were 110 nm long and 25 to 50 nm wide and were mainly conical or wedge-like in shape. Surface projections were seen on the envelope membrane of many of the virus particles; the knobs were approximately 6 nm in length, 10 nm wide and from an end-on view they had a Y or triangular-shaped morphology.

Centrifugation, Density Gradient↗