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PubMed1982

High-resolution scanning electron microscopy of human metaphase chromosomes.

Human metaphase chromosomes, prepared for light microscopy were examined by scanning electron microscopy. Use of an osmium impregnation technique eliminated the need for sputter-coating and allowed high-resolution visualization of uncoated specimens. Chromosomes were of three-dimensional cylindrical profile, with well-defined chromatids and centromeres. Prior to Giemsa-banding a smooth surface morphology was observed. Relaxation of chromosome integrity by Giemsa-banding pretreatment allowed resolution of several orders of chromosome structure not previously demonstrated by scanning electron microscopy. The observed organization of the chromatin fibres allowed parallels to be drawn with the radial loop model of chromosome construction as described by Marsden and Laemmli.

Chromosome Banding↗
PubMed2004

Comparative analysis of isolated cellular organelles by means of soft X-ray contact microscopy with laser-plasma source and transmission electron microscopy.

Soft X-ray contact microscopy (SXCM) is, at present, a useful tool for the examination at submicrometre resolution of biological systems maintained in their natural hydrated conditions. Among current X-ray-generating devices, laser-plasma sources are now easily available and, owing to their pulse nature, offer the opportunity to observe living biological samples before radiation damage occurs, even if the resolution achievable is not as high as with synchrotron-produced X-rays. To assess the potential of laser-plasma source SXCM in the study of cellular organelles, we applied it for the analysis of chloroplasts extracted from spinach leaves and mitochondria isolated from bovine heart and liver. X-ray radiation was generated by a nanosecond laser-plasma source, produced by a single shot excimer XeCl laser focused onto an yttrium target. The images obtained with SXCM were then compared with those produced by transmission electron microscopy observation of the same samples prepared with negative staining, a technique requiring no chemical fixation, in order to facilitate their interpretation and test the applicability of SXCM imaging.

Animals↗
PubMed1990

Freeze-fracture electron microscopy of in vitro reconstructed human epidermis.

Epidermis has been reconstructed in vitro by seeding human keratinocytes on a human dermal substrate in an air-exposed culture. The end product has been examined by freeze-fracture electron microscopy, transmission electron microscopy (TEM) of thin sections, light microscopy, and lipid analysis using thin-layer chromatography. Light microscopic observation of hematoxylin-eosin stained, paraffin embedded cross-sections of the cell culture revealed a strong resemblance to its intact human counterpart, especially with respect to the morphologic organization in basal, spinous, granular, and horny layers. Freeze-fracture electron microscopy and TEM of thin sections generally confirmed the observed resemblances and additionally suggested the presence of lamellar bodies in the stratum granulosum, and of lamellar (lipid) structures between the corneocytes. However, some imperfections were also observed, including some anomalous lipid structures in the intercellular space. Lipid analyses in conjunction with essential fatty acid enrichment studies suggested that the structural anomalies observed in the cultured system may be caused by a lack of linoleyl-ceramides resulting from "immobilization" of linoleyl moieties in the form of triglycerides and phospholipids. In its present form, the air-exposed cell culture already looks very promising as a model for studies of, e.g., skin differentiation disorders such as psoriasis or ichthyosis, studies of the percutaneous penetration and intra(epi)dermal biotransformation of drugs, and skin toxicity screenings. It is furthermore expected that the aforementioned imperfections in the air-exposed cell culture should be avoidable by changing culture conditions such as the relative humidity and the pH, the composition of the medium, or both.

Cells, Cultured↗
PubMed1982

Desmoplastic malignant melanoma: a study by conventional and electron microscopy.

A 61-year-old white man presented himself with a mass that had recurred on the chin. Conventional microscopy of sections from this mass showed atypical spindle cells surrounded by abundant collagen and resembled fibrosarcoma. Stains for melanin revealed pigment in the cytoplasms of the atypical spindle cells. Study of sections by electron microscopy demonstrated round, oval, and spindle-shaped cells having desmosomes and containing abundant melanosomes in varying stages of maturation. On the basis of both conventional microscopy and electron microscopy, the diagnosis was desmoplastic malignant melanoma. An unusual finding by electron microscopy was the presence of tubuloreticular intracytoplasmic inclusions in the neoplastic melanocytes.

Chin↗
PubMed1995

Banana starch breakdown in the human small intestine studied by electron microscopy.

OBJECTIVE: To determine the origin of the poor digestibility of banana starch granules in the human small intestine. DESIGN: The subjects received the same experimental meal. SETTING: Nutrition Research Unit, Laënnec Hospital, CHU, Nantes. SUBJECTS: Six healthy young subjects. INTERVENTIONS: The digestion of raw green banana flour in the upper part of the gut was studied by the intubation technique. After ingestion of 30 g banana flour mixed with a complex meal, ileal samples were continuously collected during 14 h. In order to determine the structural nature of this resistant starch, the dried ileal samples were observed with scanning and transmission electron microscopy. Transmission electron microscopy was performed after treatment with periodic acid-thiosemicarbazide-silver nitrate. RESULTS: Banana starch proved very resistant to in vivo amylase hydrolysis since 84% of the starch ingested reached the terminal ileum. The microscopic observations showed that raw banana flour contained irregularly shaped dense starch granules with smooth surfaces. After their passage through the small intestine, starch granules appeared exocorroded, with porous surfaces, and some exhibited several irregular pits, crevices or holes by which the enzymes had penetrated and hydrolysed the inner part. Cell walls closely associated with starch granules could have hindered enzyme access to starch. CONCLUSIONS: Encapsulation could be partly responsible for the low digestibility of starch in banana flour, together with the intrinsic resistance of banana starch granules.

Digestion↗
PubMed2002

Experimental trigeminal glycerol injection in dogs: histopathological evaluation by light and electron microscopy.

We investigated the effects of percutaneous gasserian glycerol injection in dogs and reviewed the histopathological changes. Experiments were performed in 16 adult healthy mongrel dogs. In group 1 (8 dogs) normal saline and in group 2 (8 dogs) pure glycerol was injected in the right trigeminal ganglion. After these procedures, dogs in each group were sacrificed after 24 h (3 dogs), 7 days (3 dogs), 21 days (2 dogs). The trigeminal ganglion and nerve of both sides were removed by using microsurgical techniques and examined by light and electron microscopy. Group 1: in all sections, nerve cells, myelinated and nonmyelinated fibers revealed normal patterns with slight fibrosis. Group 2: in all sections, myelinated fibers showed disintegration and swelling of the myelin sheath, rupture of axon continuity, destruction of basal lamina, deformation of the myelin-axon relationship by both light microscopy and electron microscopy. The sections examined by electron microscopy also showed axonolysis in nonmyelinated fibers. The changes after 7 and 21 days were less prominent than after 24 h. In the left sides, there are no pathological changes. Glycerol has a neurolytic effect on the dog's trigeminal ganglion. These effects were not specific and selective for myelinated and nonmyelinated nerve fibers.

Animals↗
PubMed1986

Scanning electron microscopy of immune complexes in membranous glomerulopathy.

Scanning electron microscopy (SEM) was done on seven cases of membranous glomerulopathy (MG) in order to describe the morphologic appearance of the immune complexes that are deposited in the glomerular basement membranes, as previous SEM studies on the human glomerulus primarily focused on the changes in the podocytes. The diagnosis of membranous glomerulopathy of idiopathic form or secondary to systemic lupus erythematosus was confirmed by conventional light and transmission electron microscopy and immunofluorescent microscopy. By SEM, the external surfaces of the basement membranes were covered by immune complexes that appeared as a network of "lumpy-bumpy" deposits. They were arranged in anastomosing cords imparting a "swiss cheese" pattern. The immune-complex nature of these anastomosing cords of deposits is confirmed by our preliminary immunoscanning electron-microscopic study. The exact mechanism for immune complexes to be localized on the external surface of the basement membrane remains to be elucidated.

Antigen-Antibody Complex↗
PubMed1988

[Electron microscopy of 300 tumors in the nervous system].

The results of 300 nervous system tumors observed by electron microscopy are reported. Of them, 12% depended on electron microscopy for diagnosis; 14% was further classified and typed by electron microscopy; 59% could be diagnosed by either electron or light microscopy but the former played an important role in confirming the diagnosis by light microscopy; 10% still could not be diagnosed even by electron microscopy; 5% failed in diagnosis due to faulty technique. The results indicate that the electron microscope is a useful tool in diagnosis of the nervous system tumor, particularly, in those whose diagnosis is difficult by light microscopy and in classification and typing of the tumor. In this paper, the pathognomonic ultrastructural features are described.

Diagnosis, Differential↗
PubMed1998

Phase-contrast microscopic studies using cinematographic techniques and scanning electron microscopy on IgE-mediated degranulation of cultured human mast cells.

BACKGROUND: Isolating human mast cells is a laborious procedure. Recently, cultured human mast cells raised from umbilical cord blood cells have become available. It is necessary to investigate whether IgE-mediated activation of these cells is mediated by exocytosis. OBJECTIVE: To verify IgE-mediated activation of these cultured human mast cells morphologically. METHODS: The mast cells were raised from human umbilical cord blood cells in the presence of stem cell factor and interleukin-6. IgE-sensitized cultured human mast cells were activated by anti-IgE, and morphological changes of the cells were examined under phase-contrast microscopy using cinematographic techniques and scanning electron microscopy. Histamine release from the cells was measured with high-performance liquid chromatography. RESULTS: Under the condition in which a significant histamine release was observed from the mast cells, phase-contrast microscopy showed that the cultured human mast cells became swollen and extruded granules. Scanning electron microscopy disclosed the extrusion of smooth and round bodies from pores formed on the activated mast cell surface. CONCLUSION: IgE-mediated histamine release from cultured human mast cells is accompanied by exocytosis morphologically, indicating that cultured human mast cells will help in studying the functional properties of human mast cells.

Cell Degranulation↗
PubMed1980

Scanning electron microscopy of the rat renal glomerulus.

Glomeruli of normal rat kidneys were studied by scanning electron microscope. A three-dimensional image is presented of the outer and the inner surface of the glomerular capillaries. The findings are compared with their correlates as seen in transmission electron microscopy. The possible application of scanning electron microscopy in the examination of renal disease is briefly discussed.

Animals↗
PubMed1989

Morphology of fibroblasts in collagen gels: a study using 400 keV electron microscopy and computer graphics.

We have used 400 kilovolt intermediate voltage electron microscopy (IVEM) to examine thick sections of fibroblasts cultured in collagen gels. In these 3D collagen lattices, the long, narrow pseudopodial extensions that extend out and make contact with the collagen matrix exhibit a complex topography not seen in the processes put out by cells moving on planar substrata. For this reason, sections 1 to 2 microns thick that enclose a whole cell process are more informative of the overall morphology of the interaction between cells and the collagen than are thin sections. To aid the discrimination of topography of cell processes in stereo views of micrographs, some cells were labeled with antibodies and protein A-colloidal gold conjugates. The gold particles provided clear 3D reference points for computer-aided reconstructions of membrane topography from tilt series of IVEM images. Our results confirm that cells that move through collagen lattices lack the well-spread morphology of their counterparts moving on glass. They are generally rather spindly with several long branching anterior pseudopodia. We found that the cell bodies and major pseudopodial processes were cylindrical, as one might expect of cells in a 3D environment, but at the leading edge of advancing pseudopodia there are small flat extensions similar to those seen in cells on glass. This similarity suggests that the lamellipodium is a basic type of protrusive structure used by fibroblasts during locomotion on all types of substratum. The flattened shape of lamellipodia may be part of the mechanism by which cells sense the orientation of fibrillar extracellular matrices during embryonic morphogenesis.

Animals↗
PubMed1987

Transmission electron microscopy studies of plasma-etched silicon nitride/silicon carbide composites.

Transmission electron microscopy has been used to isolate and examine the intergranular glass phase in hot-pressed silicon nitride/silicon carbide composites. Previously there have been difficulties in locating a suitable region for studies of this nature because the interfering nitride and carbide grains inhibit isolation of the glass for examination. Radiofrequency plasma etching of thinned sections of 6 wt% Y2O3, 2 wt% A12O3 in Si3N4 containing 30 vol% of SiC proved to be fruitful in isolating the glass phase. A mixture of CF4 and O2 quantitatively remove the acicular nitride phase without any evidence of attack on either the glass or carbide. Composites containing ceria and magnesia as substitutes for yttria behave similarly. This indicates that glasses containing minor to major concentrations of elements forming stable fluorides inhibit the attack of fluoride ions on silica glasses containing these elements.

Carbon↗
PubMed1990

Electron microscopy of hybridoma cells with special regard to monoclonal antibody production.

Electron microscopy of mouse hybridoma cell lines shows that the major difference between non, low and high producer cell lines is the amount of endoplasmic reticulum. Vesicular-tubular or cavernous structures of endoplasmic reticulum, which can survive long after cell death, are particularly abundant in producer cell lines. Immunogold labelling with anti-mouse IgG reveals that antibodies are predominantly located in these structures. The cell membrane undergoes structural changes during the late stages of batch culture with the disappearance of microvilli and the appearance of blebs and deep indentations. Necrosis disrupts the cytoplasmic structures and the nucleus is last to degrade.

Animals↗
PubMed1995

New applications of electron microscopy techniques in dermatopathology.

The application of immunostaining techniques to electron microscopy specimens has led to a renewal of interest in electron microscopy in biological research in general, as well as in dermatopathology. Refinements in the preparative procedures have made easier the immunolocalization of antigens both in chemically-fixed and frozen unfixed tissues, embedded in plastic and sectioned. Application of these methods has led to the demonstration of the bullous pemphigoid antigen inside basal keratinocytes. HMB-45 antigen has been found to be present in premelanosomes. Recently, Factor XIIIa has been localized not only in dermal dendrocytes but also in endothelial cells and mast cells.

Antigens, Neoplasm↗
PubMed1976

Modifications of mammalian cell surfaces induced by sugars: scanning electron microscopy.

Substitution of galactose, xylose, or mannose for glucose in the growth medium of L cells or the addition of equal concentrations of the alternate sugars to glucose-containing medium results in marked morphologic changes. The changes are revealed by conventional staining for light microscopy and by scanning electron microscopy. L cells grow indefinitely on combinations of equal concentrations of glucose and galactose, xylose, or mannose. There appear to be no significant differences in growth rate on glucose compared to the combinations of sugars cited. Cells subcultured from glucose to the combinations while undergoing rapid multiplication show marked morphologic changes by light and scanning electron microscopy within 36 hr. Of particular note are the loss of microvilli; flattening of the cells; assumption of polygonal shape; prominence of nuclei and nucleoli; and changes in the structure and distribution of filopodia. Virtually all cells in the population exhibit the changes noted.

Cell Division↗
PubMed2000

The diagnostic value of electron microscopy in human immunodeficiency virus-positive patients with gastrointestinal disease.

BACKGROUND: Our aim was to determine the diagnostic value of electron microscopy in evaluating the etiology of gastrointestinal disease in patients infected with the human immunodeficiency virus (HIV). METHODS: A retrospective review of electron microscopic and light microscopic results of all HIV-positive patients with gastrointestinal and liver diseases was made during a 3-year period from June 1995 to June 1998. RESULTS: A total of 145 HIV-positive patients had their electron microscopy specimens reviewed. Of these, 136 were investigated for diarrhea, and the other 9 for increased liver enzymes. Twenty-seven of the 145 (18.6%) HIV-positive patients had a pathogen identified by electron microscopy, compared with only 13 of 145 (9%) identified by light microscopy (P < 0.005). The sensitivity of light microscopy for detecting opportunistic pathogens was 68%. Twenty-one of the 27 (77.8%) patients diagnosed by electron microscopy had microsporidiosis, and the most commonly diagnosed species was Enterocytozoon bieneusi. Light microscopy failed to identify 12 cases of microsporidiosis and 2 cases of leishmaniasis. CONCLUSIONS: Electron microscopy contributes substantially to the identification of pathogens in HIV-positive patients. Light microscopy failed to identify one of every two pathogens diagnosed by electron microscopy.

Adult↗
PubMed1986

Differentiation and maturation of the sensory hair bundles in the fetal and postnatal vestibular receptors of the mouse: a scanning electron microscopy study.

By means of scanning electron microscopy, the differentiation and maturation of sensory hair bundles have been studied in the ampullar cristae of the mouse during development from gestational day 13 (GD13) to postnatal day 10 (PD10). Two gradients of ciliary differentiation were demonstrated, one from the apex to the base and the other from the center to the periphery. The different hair bundles that appeared on the crista during the fetal period originated in an initial ciliary stage found in regions undergoing differentiation, differentiation, which was visible at the apex of the crista starting on GD14. This stage of ciliary development is gradually followed by a juvenile one at GD15. Starting on GD18, the maturation of hair bundles in the central apical area differed from that in the peripheral areas and prefigured the regional specialization of the crista found in the adult stage. In the discussion, we suggest that when the vestibular epithelial cells begin to exhibit ciliary differentiation, they are simultaneously contacted by nerve fibers.

Animals↗
PubMed2006

Three-dimensional reconstruction of single particles in electron microscopy image processing.

Three-dimensional electron microscopy of single macromolecular assemblies has made large strides forward over the last decade. A large number of image processing techniques have been developed and many have found general distribution. For the proper usage of the wide range of available techniques, a clear concept of all processing steps is essential. This chapter provides step-by-step instruction for the three-dimensional reconstruction of an unknown macromolecule. Where possible, the limitations of the techniques are explained. The chapter attempts to be sufficiently general such so as not to adhere to a single image processing system. Described are alignment techniques for two and three dimensions, classification procedures, and the usage of three-dimensional reconstruction algorithms.

Algorithms↗