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PubMedDate not supplied

Imaging faces of shadowed magnetite (Fe(3)O(4)) crystals from magnetotactic bacteria with energy-filtering transmission electron microscopy.

We used energy-filtering transmission electron microscopy to image magnetite crystals isolated from uncultured magnetotactic bacteria. These magnetite crystals were shadowed in high vacuum with platinum at 45 degrees. The shadowed crystals were observed in a Zeiss (Thornwood, NY) CEM902 transmission electron microscope. Imaging shadowed crystals with inelastically scattered electrons provided information of the decoration pattern of small platinum particles over crystal surfaces, and thus information on surface characteristics of crystals. Results were comparable to those obtained from scanning electron microscopy using a field emitter gun. Electron energy loss spectra of the crystals as well as of the supporting film were recorded to evaluate variations of image contrast with energy losses. Results indicated that the contrast is attenuated with inelastic imaging and that the effect of contrast tuning caused a contrast inversion at a given point between 100 and 150 eV. We believe this approach can be useful for studying multilayered materials by transmission electron microscopy.

Bacteria↗
PubMed1998

Evidence for a unique elastic sheath surrounding the vesicular arteries of the rabbit urinary bladder--studies of the microvasculature with microscopy and vascular corrosion casting.

Because the urinary bladder stores and releases urine, its normal function includes filling and emptying, accompanied by distension and relaxation. It is known that chronic distension compromises blood flow. Recent studies of the rabbit bladder vasculature have described specializations of that vasculature that appear to enhance blood flow in the bladder wall during distension. The present report describes the location, orientation, and structure of an elastic sheath surrounding the vesicular arteries, which may represent one of these specializations. The location, vasculature, and structure of an accessory elastic sheath surrounding the vesicular arteries of the rabbit bladder is described using light and electron microscopy, India ink injection, and vascular corrosion casting. The common iliac arteries of rabbits were cannulated to permit perfusion of the distal vasculature including the urinary bladder. After the bladder vasculature was visually cleared of blood by perfusion with buffered saline, one of the following procedures was used: 1) for light or electron microscopy, the bladder was perfuse-fixed with buffered 2% glutaraldehyde; 2) the bladder vasculature was filled with India ink for vessel tracing; or 3) corrosion casts of the bladder vasculature were prepared by infusion of a Mercox resin mixture. Casts, cleaned of tissue with KOH, and water and formic acid rinses, are dried, and mounted for routine scanning electron microscopy. The presence of an accessory sheath surrounding the main vesicular arteries and some of their branches in the basal two thirds of the urinary bladder was observed on India ink injected specimens and confirmed by micrographs and vascular corrosion casts. The sheath consists of elastic and collagenous fibers and is separated from the tunica media of the arteries by a loose connective tissue layer of variable width. The sheath is circumscribed by a layer of fine blood vessels. The vesicular arteries undulate within the sheath to an extent which is dependent upon the degree of distension of the bladder. This sheath likely represents a specialization which permits the bladder vasculature to accommodate expansion and contraction of the wall during normal filling and emptying. Undulations or coiling of the vesicular arteries within the loose connective tissue core of the sheath increase with bladder contraction, and apparently the sheath simply holds the artery in position during such coiling. The sheath, may represent a modification of the external elastic lamina found in some muscular arteries.

Animal Structures↗
PubMed1999

Signal to noise analysis of multiple color fluorescence imaging microscopy.

BACKGROUND: Various approaches that were recently developed demonstrate the ability to simultaneously detect all human (or other species) chromosomes by using combinatorial labeling and fluorescence in situ hybridization (FISH). With the growing interest in this field, it is important to develop tools for optimizing and estimating the accuracy of different experimental methods. METHODS: We have analyzed the principles of multiple color fluorescence imaging microscopy. First, formalism based on the physical principles of fluorescence microscopy and noise analysis is introduced. Next, a signal to noise (S/N) analysis is performed and summarized in a simple accuracy criterion. The analysis assumes shot noise to be the dominant source of noise. RESULTS: The accuracy criterion was used to calculate the S/N of multicolor FISH (M-FISH), spectral karyotyping, ratio imaging, and a method based on using a set of broad band filters. Spectral karyotyping is tested on various types of samples and shows accurate classifications. We have also tested classification accuracy as a function of total measurement time. CONCLUSIONS: The accuracy criterion that we have developed can be used for optimizing and analyzing different multiple color fluorescence microscopy methods. The assumption that shot noise is dominant in these measurements is supported by our measurements.

Female↗
PubMed1999

Study of single-molecule dynamics and reactions with classic light microscopy.

Single-molecule studies in the life sciences often deal with observation or spectroscopy. Studies of reactions are rare, and the light microscope has been used for such experiments only occasionally. In an experimental environment, for example, as is required for most nearfield scanning or electron microscopies, it is difficult to study single-molecule reactions of biological relevance. Therefore, we have developed techniques to study single-molecule reactions with classic (nonscanning) farfield light microscopy. The conversion of nicotinamide adenine dinucleotide (NAD+) and lactate to NADH (a reduced form of NAD+), pyruvate, and H+ catalyzed by a few LDH-1 enzyme molecules has been studied in substrate solutions with different viscosity using the NADH autofluorescence. It is even possible to monitor the progress of the reaction by phase-contrast microscopy via scattering or absorption by product molecules. As an example for a single-molecule reaction with a macromolecule as substrate, the handling and enzymatic cutting of fluorescently stained lambda-DNA is studied. In solutions containing 10 mM magnesium and 66 mM potassium ions at pH 7.9, an individual DNA molecule tends to collapse into a globular structure. When moved through an aqueous solution, it becomes stretched by viscosity drag. After stopping the motion, the molecule collapses and the dynamics of this process can be quantified. When a restriction enzyme is present, sequence-specific cutting can be directly observed in the light microscope. The theoretical restriction pattern, as predicted from the sequence of the molecule, can be generated directly under visual inspection.

Bacteriophage lambda↗
PubMed1997

Confocal laser scanning microscopy and three-dimensional reconstruction of cell clusters in serous fluids.

Thick cell clusters are a common finding in reactive and malignant effusions. In order to arrive at a diagnosis, clusters are evaluated for certain cytomorphologic features including size, shape, smooth vs. scalloped borders, and three-dimensional (3-D) configuration. By conventional microscopy, the image of these clusters is often blurred due to limitations in resolution. Consequently, the exact internal structure and cellular arrangement within these clusters cannot be adequately determined. Utilizing confocal laser scanning microscopy (CLSM), we examined serous fluids from a variety of conditions. Cases included mesothelioma, adenocarcinoma, and papillary adenocarcinoma. Smears were stained with 0.01% ethidium bromide and 1% eosin Y, followed by analysis with an ACAS 570 image analyzer (Meridian Instruments, Inc. Okemos, MI). Serial confocal fluorescence images were acquired, which allowed 3-D reconstruction of the clusters. Mesothelioma clusters (excluding those with obvious central collagen cores by light microscopy) appeared to be formed of the following configurations: 1) randomly coiled cords of cells, 2) small papillae encompassing central cores, and 3) tissue fragments with pseudoacinar formation. In contrast, adenocarcinomas had a more orderly pattern, with tightly cohesive cells and true acinar formation.

Adenocarcinoma↗
PubMed1997

Atomic force microscopy and cytochemistry of chromatin from marsupial spermatozoa with special reference to Sminthopsis crassicaudata.

Atomic force microscopy (AFM) of the nuclear topology of spermatozoa from two marsupial species, Smithopsis crassicaudata and Trichosurus vulpecula was investigated to determine the structural organisation of the chromatin subunits. That of the former species is of special interest as it has a peripheral nucleohistone region (C2) as well as a nuclease-resistant, nucleoprotamine core region (C1). Atomic force microscopy showed that the C2 region contained clusters of 120-160 nm nodules, whereas the C1 region exhibited smaller 50-80 nm nodules. The spermatozoa nuclei of Trichosurus, which has mainly nucleoprotamines, contained higher order chromatin structures of similar size to those from the C1 region of Sminthopsis. This study shows that nucleohistones and nucleoprotamines of marsupial sperm form distinct higher order conformations. For the second part of this work, the chromatin density and affinity for cationic stains of Sminthopsis spermatozoa were determined. Spermatozoa were observed with the transmission electron microscopy (TEM) either unstained or stained with metal salts. In the unstained specimens, the C2 nucleohistone region appeared more electron-lucent than the C1 region. When large cations such as uranyl were used, the reverse situation was observed. Therefore, the electron-dense appearance of the C2 chromatin in conventionally stained material may be due to the presence of net negative DNA charges that attract the cations used for EM staining, whereas the C1 chromatin may lack excess DNA negative charges that attract these stains and thus appears less electron-dense.

Animals↗
PubMed1981

Electron microscopy in the diagnosis of malignant schwannoma.

Fifteen malignant schwannomas were examined by light and electron microscopy. Five tumors arose in patients with neurofibromatosis and five were contiguous with a peripheral nerve (Group I). Five tumors met neither of these generally accepted diagnostic criteria but were light microscopically seen as compatible with malignant schwannoma when examined under light microscope (Group II). In the better differentiated areas of Group I lesions, long, overlapping, tightly packed cytoplasmic processes were parallel to homogeneous flocculent material, occasionally assuming a linear appearance suggesting basal lamina. In Group II, similar cytoplasmic processes were present but the extracellular material was less extensive and had a less obvious relationship to the plasma membrane. In neither group were fine intracytoplasmic filaments prominent. Malignant schwann cells are seldom as ultrastructurally differentiated as their benign counterparts. Nevertheless, within the context of well-studied light microscopy and the sampling error inherent in ultrastructural examination, electron microscopy can support the diagnosis of malignant schwannoma.

Adult↗
PubMed1982

A comparison of World Health Organization (WHO) classification of lung tumors by light and electron microscopy.

Forty-nine cases of lung tumor were initially classified according to the World Health Organization (WHO) system by light microscopy. Additional study by electron microscopy using only a minimum of ultrastructural features as criteria for each type made more precise classification of some of the poorly differentiated or undifferentiated tumors possible. Most significant was the finding of evidence of a second tumor type in nine of the 35 tumors previously classified as moderately to well differentiated thus reclassifying them as mixed tumors. Sixteen of the 49 tumors were reclassified and a more precise classification was made in five others. Only two cases of undifferentiated small cell tumors were available and no unequivocal neurosecretory granules could be found in either. Correlation of the more precise typing of lung tumors by electron microscopy with the clinical data and modes of therapy will provide necessary information for determining the usefulness of the WHO classification.

Adenocarcinoma↗
PubMed1983

Electron microscopy in the diagnosis of malignant schwannomas. A report of six cases.

The diagnosis of malignant schwannoma may be difficult or impossible by light microscopy alone, if the neoplasm is poorly differentiated and if there is no clinical evidence for its arising from a nerve-trunk. Six cases of malignant schwannoma in which electron microscopy confirmed or established the diagnosis are reported. In four cases, the anatomic origin of the neoplasm arising from a large nerve was demonstrated at the time of operation, and in one of these the patient had von Recklinghausen's disease. In three of the four cases, as well as in the fifth case, in which the tumor was associated with an overlying malignant melanoma, the distinctive schwannoma patterns of Antoni types A and B tissue were absent. In the sixth case, there were no clinical clues as to nerve sheath origin, but both the light and electron microscopic features of the neoplasm were very characteristic of Schwann cell derivation. The most consistently present, ultrastructural features of malignant schwannoma are the spindle shape of the cells and the terminal cytoplasmic processes. If the processes show intertwining and if lateral cell borders are interdigitated, the diagnosis is more readily confirmed. Likewise, basal lamina is an important diagnostic feature but may be scant and focal in the very cellular and less differentiated tumors. Microfilaments are usually present, albeit in varying numbers, and they do not form the dense bodies seen in smooth muscle cells. Other diagnostically useful, but less consistent characteristics include microtubules, primary and secondary lysosomes, and dense-core type granules. Long-spacing collagen was present in only one case and in none of those reviewed from the literature. This is also an important finding. It is probable that most malignant nerve sheath neoplasms arise from Schwann cells, rather than from fibroblasts or perinurial cells, but electron microscopy often will be necessary to confirm this impression.

Adult↗
PubMed1990

Capillary microscopy is a potentially useful method for detecting bleomycin vascular toxicity.

Capillary microscopy is an easy, noninvasive procedure to examine in vivo the dermis capillaries of the nailfold. It has demonstrated clinical use in the etiologic study of Raynaud's phenomenon. We consider a "vascular activity pattern" to be present at capillary microscopy when one of the following associations is observed: tortuous capillary vessels plus ramifications with or without loss of a moderate amount of capillaries. Capillary tortuousity alone is not considered pathologic. It is well known that bleomycin (BLEO) can occasionally induce vascular-associated diseases. To examine the vascular damage produced by BLEO, we performed capillary microscopic studies on 40 patients with neoplasia, 21 of whom had received BLEO during the previous year. The maximum accumulated doses ranged from 15 to 379 U. The other 19 patients had advanced neoplasia, and 10 of them had received antitumoral combinations that did not contain BLEO. No one had clinical signs attributable to vascular toxicity. Twenty-six patients had no pathologic patterns (11 received BLEO and 15 did not). In the group of 14 patients with activity patterns, 10 had received BLEO and 4 had not (P = 0.035). Ten of 11 patients treated with BLEO who had normal capillary microscopic studies received total doses of less than 100 U. We conclude that capillary microscopy may demonstrate the vascular damage induced by BLEO even in asymptomatic patients.

Bleomycin↗
PubMed1991

Usefulness of electron microscopy in the diagnosis of congenital dyserythropoietic anemia type I: report of a case.

This report describes a case of congenital dyserythropoietic anemia (CDA) type I diagnosed in a 22-year-old woman with a two year history of macrocytic anemia. Light microscopy study of bone marrow disclosed only minor and nonspecific findings, without erythroid hyperplasia. Electron microscopy of bone marrow erythroblasts surprisingly showed most of the classical features of CDA type I. Electron microscopy may be an important tool for the diagnosis of macrocytic anemia of obscure origin, especially in young patients.

Adult↗
PubMed1984

The value of graphic reconstructions--comparison with scanning electron microscopy.

Because knowledge of spatial morphology of the human embryonic heart mainly derives from serial microscopic sections and from reconstructions based on such series, it might be questioned whether the results obtained are comparable with animal studies in which scanning electron microscopy is used. Therefore, pig embryo hearts of the same developmental stage were processed for routine histological sectioning as well as for scanning electron microscopy. A graphic reconstruction was made of a right ventricular view, to be compared with a similar scanning micrograph. The two images, produced by much different techniques, were strikingly similar. In addition, the graphic reconstruction technique is complementary to scanning electron microscopy, because histological details can be introduced.

Animals↗
PubMed1988

A survey by scanning electron microscopy of the extracellular matrix and endothelial components of the primordial chick heart.

Scanning electron microscopy was used to study the morphogenesis of the primitive embryonic chick heart (stage 5 late primitive streak through stage 9+). Components of the developing heart (myocardium, endocardial endothelium, and extracellular matrix) were viewed from the ventral surface after removal of the endoderm. The myocardial component of the heart can first be seen by light microscopy at stage 5 as two darker oval-shaped areas located on either side of the embryonic axis in the cranial region of the embryo. Scanning electron microscopy demonstrates that as early as stage 6 an area of extracellular matrix, enriched in comparison to more lateral and medial splanchnic mesoderm, can be identified ventral to the myocardial primordium. As heart formation progressed we observed primordial endothelial elements in the splanchnic mesoderm lateral to the myocardial primordia. By late stage 7 these lateral primordial elements had anastomosed into small, loose plexuses. This process of anastomosis progressed rapidly, and by stage 8 the entire cranial surface of the myocardial primordium was covered with vascular plexuses. By late stage 8 the progressive fusion of these plexuses resulted in the formation of large multiple tubular elements near the midline. More medially the fusion of tubular elements resulted in a continuous endothelial sheet at the midline.

Animals↗
PubMed1995

Atrioventricular valves of the mouse: II. Light and transmission electron microscopy.

BACKGROUND: Mouse atrioventricular (AV) valves present a number of conspicuous morphologic differences with human AV valves. Given the existence of these differences, it is important to know the structural organization of mouse AV valves. Since the mouse is often considered to be a good animal model for developmental and anatomical studies, the presence of significant differences in structure may render comparative studies difficult. In addition, we wished to learn about the existence of structural changes in the mouse AV valves with age. METHODS: The structural organization of mouse AV valves from 21 days to 1 year of age was studied by polarizing microscopy and by conventional light and transmission electron microscopy. RESULTS: Polarizing microscopy reveals the presence of a system of birefringent fibers that consist of collagen bundles that organize like tendons. The spatial organization of these fibers is different in the two AV valves, reflecting differences in the anatomy of the entire valvular complex. Interstitial cells (IC) are of two different phenotypes: some are typical fibroblasts, while some others share smooth muscle cell characteristics. In addition, small areas of fibrocartilage are also observed. The compactness and thickness of the collagen bundles increase with age. Also with age, the basement membranes become thickened or multilayered, and matrix vesicles and deposits of amyloid P can be observed. CONCLUSIONS: The collagenous birefringent fibers form an internal skeleton that should transmit the cycling stress evenly over the entire leaflets. IC should help to maintain the structure and deformability of the valve tissue and appear actively involved in the synthesis and renewal of extracellular material. The cartilaginous foci appear to be a normal component of the valve tissue. The structural changes observed in old animals appear to be related to the degenerative processes which take place in normal valvular tissues with age. Despite the structural differences, age changes appear to be similar in the AV valves of mouse and man.

Aging↗
PubMed1987

In vivo capillary microscopy findings and ophthalmoscopy findings in scleroderma.

We used in vivo capillary microscopy to examine the nailfold capillaries of 19 patients with scleroderma (18 women and 1 man; average age 56.6), and compared these findings with those obtained using an ophthalmoscope. The ophthalmoscope revealed hemorrhages in 68% of the patients, a reduction in the number of capillaries in 79%, avascular areas in 79%, and dilated capillaries in 84%. The findings from ophthalmoscopy showed a correlation of approximately 80% with those from capillary microscopy. Since the diagnosis of scleroderma can be confirmed with this instrument, we suggest that it be used when microscopy equipment is not available.

Adult↗
PubMed2004

Quantifying anisotropic solute transport in protein crystals using 3-D laser scanning confocal microscopy visualization.

The diffusion of a solute, fluorescein into lysozyme protein crystals has been studied by confocal laser scanning microscopy (CLSM). Confocal laser scanning microscopy makes it possible to non-invasively obtain high-resolution three-dimensional (3-D) images of spatial distribution of fluorescein in lysozyme crystals at various time steps. Confocal laser scanning microscopy gives the fluorescence intensity profiles across horizontal planes at several depths of the crystal representing the concentration profiles during diffusion into the crystal. These intensity profiles were fitted with an anisotropic model to determine the diffusivity tensor. Effective diffusion coefficients obtained range from 6.2 x 10(-15) to 120 x 10(-15) m2/s depending on the lysozyme crystal morphology. The diffusion process is found to be anisotropic, and the level of anisotropy depends on the crystal morphology. The packing of the protein molecules in the crystal seems to be the major factor that determines the anisotropy.

Biological Transport↗
PubMed1975

Scanning electron microscopy of the subarachnoid space in the dog. III. Cranial levels.

Young dogs were anesthetized by intrathoracic injection of sodium pentobarbital and perfused with buffered aldehydes. Lining tissue samples from the cranial subarachnoid space were prepared for scanning electron microscopy (SEM) by postfixing in buffered OSO4. Samples were then dehydrated, dried in a Critical Point Drying System, and coated with carbon and palladium-gold. Specimens were viewed in a Cambridge S4 scanning electron microscope. After thorough scanning, selected samples were routinely prepared for transmission electron microscopy (TEM) and viewed in a Philips EM-200 transmission electron microscope. This study depicts the surface morphology of the meningeal linings of the cranial subarachnoid space. The cranial pia mater possesses natural gaps or fenestrations between cells. SEM reveals a more complex morphology of arachnoid trabeculae than previously interpreted from light and transmission electron microscopy. Many free cells are observed on the meningeal linings of the subarachnoid space. The present study establishes that these free cells are macrophages by means of definitive TEM correlates. Microvillous-like processes extending between macrophages and the pial surface are present. The frequency and the nature of these thin processes suggest the possibility of a plasmalemma-mediated system of communication.

Animals↗
PubMed1979

Rods and cones in the mouse retina. I. Structural analysis using light and electron microscopy.

Rods and cones of the C57BL/6J mouse retina have been examined by light and electron microscopy to distinguish the structural features of the two photoreceptor types. By light microscopy, cone nuclei are conspicuously different from rod nuclei in 1-2 micrometer plastic sections. Cone nuclei have an irregularly shaped clump of heterochromatin that appears in single sections to be one to three clumps, whereas rod nuclei are more densely stained and have one large, central clump of heterochromatin. Cone nuclei make up approximately 3% of the photoreceptor nuclei in both the central and peripheral retina at all ages examined up to 267 days. Cone nuclei are confined to the outer half of the outer nuclear layer, and more than 50% of the cone nuclei lie adjacent to the outer limiting membrane. By electron microscopy, cones in the mouse retina meet virtually every morphological criterion of mammalian cones. The outer segments are conically shaped. Many, if not all of the outer segment discs are continuous with the outer plasma membrane, whereas almost all of the rod discs are not. Cone outer segments are only about half the length of the rod outer segments, and they are contacted by long, villous pigment epithelial cell processes. The cone inner segment diameter is greater than the outer segment diameter, and the accumulation of mitochondria present at the apical end of the inner segment forms a more conspicuous ellipsoid than in rods. The internal fiber or axon of the cone is larger in diameter than that of the rod, and it terminates in a large synaptic pedicle with multiple ribbon synapses, whereas the rod terminal is a smaller spherule with only a single ribbon synaptic complex.

Animals↗