scholarly journals ULTRASTRUCTURE AND CALCIUM TRANSPORT IN CRUSTACEAN MUSCLE MICROSOMES

1971 ◽  
Vol 48 (1) ◽  
pp. 49-60 ◽  
Author(s):  
R. J. Baskin
Keyword(s):  
Freeze Drying ◽  
Calcium Uptake ◽  
Membrane Thickness ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Crustacean Muscle ◽  
Thin Sectioning ◽  
Critical Point Drying ◽  
Freeze Etching ◽  
Microscopic Techniques

Fragmented sarcoplasmic reticulum (FSR) from crustacean muscle was examined following preparation by a variety of electron microscopic techniques. The 30–40 A particles which appeared on the outer surface of FSR vesicles following negative staining were not observed following preparation by freeze-drying, freeze-etching, thin sectioning, or critical-point drying. Crustacean FSR exhibited high values of calcium uptake and extensive nodular formation in the presence of oxalate. 80–90 A diameter membrane particles were seen in freeze-etch preparations of both intact lobster muscle and FSR vesicles. Thin sections of FSR vesicles revealed a membrane thickness of 60–70 A. The membrane appeared to be triple layered, each layer having a thickness of 20–25 A.

Ultrastructure of Staphylococcus epidermidis after freeze-etching and thin sectioning

1973 ◽  
Vol 19 (2) ◽  
pp. 294-295
Author(s):  
James E. Gilchrist ◽  
Irving W. DeVoe
Keyword(s):  
Staphylococcus Aureus ◽  
Outer Layer ◽  
Staphylococcus Epidermidis ◽  
Cell Walls ◽  
Cytoplasmic Membrane ◽  
Middle Layer ◽  
Dense Layer ◽  
Thin Sections ◽  
Thin Sectioning ◽  
Freeze Etching

A considerable quantity of information is now available on the ultrastructure of Staphylococcus (1, 2, 4, 7, 8, 10, 11, 12). Cell walls of these organisms in thin sections have been shown to consist of three layers: a dense outer layer, a rather electron translucent middle layer, and a very dense layer next to the cytoplasmic membrane (2, 7, 11, 12). Bulger and Bulger (2) have pointed out the presence of circumferential substructure in the middle layer of the wall in a strain of Staphylococcus aureus isolated as the causative agent in fatal pneumonia.Numerous mesosomes of both the vesicular and laminar types are evident in thin sections of staphylococci from several studies (1, 4, 7, 11). Moreover, single vesicular structures that appear to be invaginations of the trilaminar cytoplasmic membrane have been pointed out by Suganuma (11) and Beaton (1).

Electron Microscopic Observations on Virus-Like Particles of a Catfish Papilloma

1977 ◽  
Vol 35 ◽  
pp. 394-395
Author(s):  
M. R. Edwards ◽  
W. A. Samsonoff
Keyword(s):  
Endoplasmic Reticulum ◽  
Major Part ◽  
Osmium Tetroxide ◽  
Electron Microscopic ◽  
Brown Bullhead ◽  
Thin Sections ◽  
Lower Lip ◽  
Virus Like Particles ◽  
Tumor Tissues ◽  
Microscopic Techniques

Papillomas in catfishes have been described (1) but the presence of viruses in these tumors has not (2). This report is concerned with the study of a papilloma found on the lower lip of a brown bullhead (letalurus nebulosus) which had been frozen prior to arrival at our laboratory.Tumor tissues were thawed in 2.5% glutaraldehyde and postfixed in 1$ osmium tetroxide. Both fixatives were prepared in Millonig's buffer. Fixation, washing, dehydration, and Epon embedding were accomplished according to conventional electron microscopic techniques.Examination of thin sections revealed virus-like particles in epidermal cells which constituted the major part of the neoplasm (Fig. 1). No particles were found in the connective tissue surrounding the epidermal papillae. The cells containing particles were usually isolated from one another, had a spindle or fusiform shape, and exhibited many cytoplasmic extensions in random directions. Their nuclei were pleomorphic and displayed irregular nuclear envelopes with relatively large lacunae. Vesiculation of the cytoplasm was extensive, apparently caused by dilations of the endoplasmic reticulum.

scholarly journals Freezing of tissue-limits for the autoradiographic localization of diffusible substances.

1979 ◽  
Vol 27 (11) ◽  
pp. 1520-1523 ◽  
Author(s):  
P M Frederik ◽  
W M Busing
Keyword(s):  
Surface Layer ◽  
Electron Microscope ◽  
Crystal Growth ◽  
Freeze Drying ◽  
Crystal Size ◽  
Ice Crystals ◽  
Ice Crystal ◽  
Thin Sections ◽  
Freeze Dried ◽  
Freeze Etching

Frozen thin sections and sections from freeze-dried and embedded tissue are used for the autoradiographic localization of diffusible substances at the electron microscope level. The presence of ice crystals in such sections may limit the autoradiographic resolution. Ice crystals are formed during freezing and may grow during subsequent processing of tissue. The contribution of ice crystal growth to the final image was estimated by measuring the distribution of the ice crystal sizes in freeze-etch replicas and in sections from freeze-dried and embedded tissues. A surface layer (10-15 mu) without visible ice crystals was present in both preparations. Beneath this surface layer the diameter of ice crystals increased towards the interior with the same relationship between crystal size and distance from the surface in the freeze-etch preparation as in the freeze-dry preparation. Ice crystal growth occurring during a much longer time during freeze-drying compared to freeze-etching does not significantly contribute to the final image in the electron microscope. The formation of ice crystals during freezing determines to a large extent the image (and therefore the autoradiographic resolution) of freeze-dry preparations and this probably holds also for thin cryosections of which examples are given.

ULTRASTRUCTURE OF THE NEUROHYPOPHYSIS AS SHOWN BY FREEZE-ETCHING

1970 ◽  
Vol 48 (4) ◽  
pp. 575-583 ◽  
Author(s):  
A. LIVINGSTON
Keyword(s):  
Internal Structure ◽  
Nerve Endings ◽  
Electron Microscopic ◽  
Freeze Etching ◽  
Hormone Granules ◽  
Microscopic Techniques

SUMMARY Freeze-etched preparations of rabbit neurohypophysis and isolated hormone granules from cow neurohypophyses were examined electron microscopically. Many features seen in conventionally prepared sections were also apparent in freeze-etched replicas, particularly the neurosecretory nerve-endings containing elementary granules and elongated pituicyte processes. Measurements of diameters of both isolated and hormone-containing granules in situ indicated that they were slightly larger in freeze-etched material than in that prepared by conventional electron microscopic techniques. Fractures through the cores of hormone-containing granules showed a lamellar internal structure of 4 nm periodicity in both species examined.

Bacterial conjugation: Scanning Electron Microscopy confirms the lightoptical impressions and the TEM observations in Escherichia Coli K 12

1986 ◽  
Vol 44 ◽  
pp. 242-243
Author(s):  
W.H. Schreil ◽  
Elisabeth Ingoliç
Keyword(s):  
Electron Microscopic Observation ◽  
Cellular Interaction ◽  
Cell Contact ◽  
Bacterial Conjugation ◽  
Electron Microscopic ◽  
The Past ◽  
Thin Sectioning ◽  
Freeze Etching ◽  
K 12 ◽  
Scanning Electron

Although 40 years have passed since the discovery of bacterial conjugation and earliest electron microscopic observation, the nature of the cellular interaction that occurs during DNA transfer from donor to recipient is still obscure. In particular, the question of whether this transfer requires close cell contact or whether some form of conjugation tube is involved, remained controversial. We had in the past identified some events in conjugation by thin sectioning and more recent by freeze etching techniques and did postulate a temporary fusion, but observations of the entire unsectioned and unfractured cells in their behaviour did present a missing link.

The biosynthesis of cellulose by Acetobacter xylinum and Acetobacter acetigenus

1977 ◽  
Vol 23 (6) ◽  
pp. 701-709 ◽  
Author(s):  
J. Ross Colvin ◽  
Gary G. Leppard
Keyword(s):  
Cell Envelope ◽  
Acetobacter Xylinum ◽  
Cellulose Microfibrils ◽  
Cellulose Synthesis ◽  
Electron Microscopic ◽  
Air Drying ◽  
Thin Sections ◽  
Morphological Aspects ◽  
Transmission Electron ◽  
Freeze Etching

The morphological aspects of biosynthesis of cellulose by Acetobacter xylinum and Acetobacter acetigenus were studied by transmission electron microscopy of both freeze-etch replicas and sections of cellulose-free cells in suspension culture before and subsequent to the induction of cellulose synthesis. Also examined were freshly synthesized, thoroughly washed, cellulose pellicles. Thin sections of rapidly dividing, glucose-metabolizing cells of both species showed irregular features on the cell surface including a small polar invagination which sometimes contained or was associated with fibrils as fine as 3 nm in diameter of a substance which stains with electron-microscopic counterstains. Cellulose microfibrils in thin sections of freshly synthesized pellicles were coated with a surface material which also stained with the same counterstains (uranyl ions and lead ions). The effect of air-drying on freshly synthesized cellulose was striking. When examined by freeze-etching, thoroughly washed, never air-dried pellicles of both species showed a nascent form of cellulose fibril which consisted of a central, dense core surrounded by a sheath of amorphous gel. This sheath may be up to 100 nm wide. When the pellicle was air-dried and rehydrated before freeze-etching, the amorphous sheath was rare and shrunken but ordinary microfibrils of classical dimensions were visible. The sheath and core are sometimes closely associated with the envelope of the cells of both species. These observations can be interpreted in the context of recent advances in cellulose synthesis by assuming that chains of an initial, highly hydrated, intermediate polyglucan are released from the cell and that such chains associate to form a nascent fibril external to the cell but associated with the cell envelope. Air-drying of nascent fibrils converts them to classical microfibrils and this conversion is considered here in molecular terms.

scholarly journals Polypeptides of the chloroplast envelope membranes as visualized by immunochemical techniques.

1986 ◽  
Vol 34 (5) ◽  
pp. 577-583 ◽  
Author(s):  
J van Berkel ◽  
M Steup ◽  
W Völker ◽  
H Robenek ◽  
U I Flügge
Keyword(s):  
Outer Membrane ◽  
Spinacia Oleracea ◽  
Leaf Tissue ◽  
Fluorescein Isothiocyanate ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Microscopic Evaluation ◽  
Freeze Etching

The polypeptides of relative molecular masses (Mr) 22,000, 29,000, and 36,000 represent three major constituents of the chloroplast envelope of spinach (Spinacia oleracea L.) leaves. The Mr 22,000 polypeptide has been localized in the outer membrane, whereas the two other peptides have been attributed to the inner envelope membrane (Joyard et al., 1983). The Mr 29,000 polypeptide has been identified as the "phosphate translocator" (Flügge and Heldt, 1979). In this investigation, we studied the three envelope polypeptides by means of immunocytochemistry. Using indirect immunofluorescence, all three polypeptides were visualized in cryostat sections of formaldehyde-fixed leaf tissue. They were found in both palisade and spongy parenchyma cells and in guard cells, as indicated by a strong fluorescence in the chloroplast periphery. In contrast, fluorescein isothiocyanate or protein A-gold labeling of isolated fixed chloroplasts resulted only in visualization of the Mr 22,000 polypeptide, a constituent of the outer membrane. We further studied the morphological distribution and frequency of this peptide by electron microscopic evaluation of platinum-carbon replicas after freeze-etching or label-fracture and of ultra-thin sections. By use of these three methods, the polypeptide was found to be randomly distributed in the outer envelope membrane and easily accessible to the immunomarker. Average marker density, as obtained by freeze-etching and label-fracture, was approximately 130 gold particles per square micron.

Force Modulation Elasticity Mapping of Plastic-embedded, Thin-sectioned Skeletal Muscle

2001 ◽  
Vol 7 (1) ◽  
pp. 32-38
Author(s):  
Boris B. Akhremitchev ◽  
Henry G. Brown ◽  
Scott R. Graner ◽  
Gilbert C. Walker
Keyword(s):  
Skeletal Muscle ◽  
Atomic Force Microscopy ◽  
Biological Material ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Force Microscopy ◽  
Force Modulation ◽  
Atomic Force ◽  
The Difference ◽  
Microscopic Techniques

AbstractWe have been researching the capability of atomic force microscopy to reveal nontopographic properties of tissue embedded in plastic and sectioned with standard electron microscopic techniques. We present topography and elasticity maps of plastic-embedded, thin sections of muscle tissue. The images show topography correlated with the normal repeating structure of the sarcomere. Elasticity mapping using force modulation revealed contrast between the actin- and myosin-rich areas. We attribute the observed contrast in elasticity to the difference in local concentrations of biological material in embedding plastic.

The Critical Point Drying Method Applied to Scanning Electron Microscopy of L-929 Cells

1970 ◽  
Vol 28 ◽  
pp. 278-279
Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Surface Tension ◽  
Critical Point ◽  
Freeze Drying ◽  
Attractive Alternative ◽  
Crystal Formation ◽  
Critical Point Drying ◽  
Time Required ◽  
Scanning Electron

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.

Preparatory Procedures for Electron Microscopic Analysis at the Molecular Level of Resolution

1978 ◽  
Vol 36 (3) ◽  
pp. 516-520
Author(s):  
F.J. Sjostrand
Keyword(s):  
Electron Microscope ◽  
Molecular Level ◽  
Microscopic Analysis ◽  
Resolving Power ◽  
Cellular Structures ◽  
Electron Microscopic ◽  
Systematic Analysis ◽  
Technical Developments ◽  
Thin Sectioning ◽  
Obvious Reason

In the 1940's and 1950's electron microscopy conferences were attended with everybody interested in learning about the latest technical developments for one very obvious reason. There was the electron microscope with its outstanding performance but nobody could make very much use of it because we were lacking proper techniques to prepare biological specimens. The development of the thin sectioning technique with its perfectioning in 1952 changed the situation and systematic analysis of the structure of cells could now be pursued. Since then electron microscopists have in general become satisfied with the level of resolution at which cellular structures can be analyzed when applying this technique. There has been little interest in trying to push the limit of resolution closer to that determined by the resolving power of the electron microscope.

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