scholarly journals Improvements of glycol methacrylate. I. Its use as an embedding medium for electron microscopic studies.

1977 ◽  
Vol 25 (3) ◽  
pp. 163-174 ◽  
Author(s):  
R C Spaur ◽  
G C Moriarty
Keyword(s):  
Electron Beam ◽  
Water Soluble ◽  
Cross Linking ◽  
Electron Microscopic ◽  
Glycol Methacrylate ◽  
Ultrastructural Studies ◽  
Tissue Morphology ◽  
Methacrylate Monomer ◽  
Microscopic Studies ◽  
Embedding Medium

The technique for using the water-soluble embedding medium glycol methacrylate has been improved for ultrastructural studies by the simplification of the method of formation of prepolymers used in embedding the tissue, by the addition of a cross-linking agent so that sections are stable in the electron beam, and by improving the softness of the blocks by the addition of a plasticizing agent. The preservation of tissue morphology has been improved by complete dehydration in glycol methacrylate monomer prior to infiltration with the prepolymer. Preservations of tissue morphology is further enhanced by complete dehydration in ethanols and embedding in the improved glycol methacrylate medium.

Glomerular Mesangial Fibrosis in Hatchery-Reared Rainbow Trout (Salmo gairdneri)

1976 ◽  
Vol 33 (11) ◽  
pp. 2551-2559 ◽  
Author(s):  
David E. Hinton ◽  
Raymond T. Jones ◽  
Roger Lee Herman
Keyword(s):  
Rainbow Trout ◽  
Mesangial Cells ◽  
Salmo Gairdneri ◽  
Unknown Etiology ◽  
Electron Microscopic ◽  
Glomerular Lesion ◽  
Ultrastructural Studies ◽  
Glomerular Lesions ◽  
Microscopic Studies ◽  
Rate Comparison

Light and electron microscopic studies were performed on tissues of hatchery-reared rainbow trout (Salmo gairdneri) having a disease of currently unknown etiology with external symptoms of severe edema which causes increased mortality rate. Comparison with unaffected trout tissues revealed loss of cellularity in glomerular tufts with a replacement of mesangial cells by connective tissue. Ultrastructural studies showed the material to be collagen and established the diagnosis of glomerular mesangial fibrosis. The glomerular lesion was associated with alterations in lining epithelium of proximal tubules and extensive debris within tubule lumens. The findings are compared to glomerular lesions in mammalian and amphibian kidney.

Ultrastructure of Septa from the Filamentous Fungus Aspergillus Nidulans

1998 ◽  
Vol 4 (S2) ◽  
pp. 1142-1143
Author(s):  
Elizabeth A. Richardson ◽  
Michelle Momany
Keyword(s):  
Aspergillus Nidulans ◽  
Filamentous Fungus ◽  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Temperature Sensitive ◽  
Electron Microscopic ◽  
Genetic Studies ◽  
Ultrastructural Studies ◽  
Microscopic Studies ◽  
Dialysis Membranes

The filamentous fungus Aspergillus nidulans partitions its cells by laying down septa at regularly spaced intervals in response to nuclear division. Physiological and genetic studies of the temperature-sensitive sep mutants have been especially useful in dissecting the regulation of septation. Electron microscopic studies of the sep mutants should be equally useful in dissecting the structural intermediates of septation. In preparation for ultrastructural studies of the sep mutants, we have examined septa in wild-type A. nidulans fixed by freeze substitution.Dialysis membranes were placed on rich medium plates and inoculated with A. nidulans spore suspensions. After 12 hours at 30°C, the dialysis membranes with adhering fungal hyphae were cut into square pieces measuring approximately 5mm on each side. The pieces were plunged into liquid propane and processed according to the procedures of Hoch. Serial sections were cut using a diamond knife and post stained with uranyl acetate and lead citrate.

scholarly journals FliG Subunit Arrangement in the Flagellar Rotor Probed by Targeted Cross-Linking

2005 ◽  
Vol 187 (16) ◽  
pp. 5640-5647 ◽  
Author(s):  
Bryan J. Lowder ◽  
Mark D. Duyvesteyn ◽  
David F. Blair
Keyword(s):  
High Yield ◽  
Cross Linking ◽  
Amino Acid Residues ◽  
Electron Microscopic ◽  
Bacterial Flagellum ◽  
Terminal Domain ◽  
Complex Protein ◽  
Microscopic Studies ◽  
Discrete Domains ◽  
Α Helix

ABSTRACT FliG is a component of the switch complex on the rotor of the bacterial flagellum. Each flagellar motor contains about 25 FliG molecules. The protein of Escherichia coli has 331 amino acid residues and comprises at least two discrete domains. A C-terminal domain of about 100 residues functions in rotation and includes charged residues that interact with the stator protein MotA. Other parts of the FliG protein are essential for flagellar assembly and interact with the MS ring protein FliF and the switch complex protein FliM. The crystal structure of the middle and C-terminal parts of FliG shows two globular domains joined by an α-helix and a short extended segment that contains two well-conserved glycine residues. Here, we describe targeted cross-linking studies of FliG that reveal features of its organization in the flagellum. Cys residues were introduced at various positions, singly or in pairs, and cross-linking by a maleimide or disulfide-inducing oxidant was examined. FliG molecules with pairs of Cys residues at certain positions in the middle domain formed disulfide-linked dimers and larger multimers with a high yield, showing that the middle domains of adjacent subunits are in fairly close proximity and putting constraints on the relative orientation of the domains. Certain proteins with single Cys replacements in the C-terminal domain formed dimers with moderate yields but not larger multimers. On the basis of the cross-linking results and the data available from mutational and electron microscopic studies, we propose a model for the organization of FliG subunits in the flagellum.

Visualization of native chromatin fibers in different embedding media

1978 ◽  
Vol 36 (2) ◽  
pp. 222-223
Author(s):  
Sebastian Muñoz-Guerra ◽  
Juan A. Subirana
Keyword(s):  
Fine Structure ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Water Soluble ◽  
Critical Importance ◽  
Thin Sections ◽  
Glycol Methacrylate ◽  
Embedding Medium ◽  
Holothuria Polii

The influence of the embedding medium is of critical importance in the observation of nucleoprotein structures in thin sections. The use of conventional epoxi media requires dehydratation, impregnation and subsequent polymerization, which may produce drastic alterations in the fine structure of chromatin. The use of water soluble embedding media may lead to improvements in the preservation of ultrastructure. In this paper we explore the differences which may be detected in nucleohistone fibers embedded in different media.Spermatozoa from Holothuria polii were subjected to moderate lysis in either 0.15M NaCl, ImM Tris-HCl, 0.4mM CaCl2, pH 8.0 (a) or 0.25M sucrose, 0.4mM CaCl2 (b) and then fixed by addition of 2 % glutaralde- hyde. Embedding was carried out as described in the literature in the following media: araldite-epon mixture (AREPO), glycol methacrylate (GMA, 1), hydroxipropyl methacrylate (HPMA, 2) and bovine serum albumin (BSA, 3) or histones.

The Connective Tissue Matrix of Cartilage as Revealed by Standard Fixation, Ruthenium Staining, High-Pressure Freezing, and Embedding in Water Soluble Media: A Comparison of Methods

1990 ◽  
Vol 48 (2) ◽  
pp. 326-327
Author(s):  
Douglas R. Keene
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Ruthenium Red ◽  
Water Soluble ◽  
High Pressure Freezing ◽  
Electron Microscopic ◽  
Microscopic Evaluation ◽  
Embedding Medium

Proteoglycan is a major component of the cartilage extracellular matrix, and the overall structure of this anionic molecule is highly dependent on the hydrated environment of cartilage. Without specific stabilization, proteoglycans are extracted or collapsed during deydration while processing for electron microscopy. The purpose of these experiments is to determine a method by which the structure of proteoglycans might be stabilized for electron microscopic evaluation.Chick sternal cartilage was prepared for transmission electron microscopy by the following methods and the resultant tissue ultrastructure compared: A) 1.5/1.5% gluteraldehyde/paraformaldehyde and 1% OsO4 fixation, dehydration in ethanol, propylene oxide, and embedding in Spurrs epoxy B) Fixation as in (A) directly followed by infiltration and embedding in Hexamethylol-melamine-methyl-ether (a water soluble embedding medium) trade name “nanoplast” C) Fixation by high pressure freezing followed by freeze substitution in acetone/OsO4 prior to embedding in epon 812. In variations of methods A and B above, ruthenium red (RR, 1500 ppm) or ruthenium hexamine trichloride (RHT, 6000 ppm) were added to the primary and secondary fixatives. All tissue sections were stained in uranyl acetate and lead citrate.

scholarly journals Fatigue-Induced Evolution of AISI 310S Steel Microstructure after Electron Beam Treatment

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4567
Author(s):  
Sergey Konovalov ◽  
Yurii Ivanov ◽  
Victor Gromov ◽  
Irina Panchenko
Keyword(s):  
Surface Layer ◽  
Electron Beam ◽  
Fatigue Life ◽  
Fatigue Testing ◽  
Electron Beams ◽  
Electron Microscopic ◽  
Pulsed Electron Beam ◽  
Steel Microstructure ◽  
Microscopic Studies ◽  
As Stress

Research was carried out to explore the effect of pulsed electron beam irradiation on the behavior of structure and phase state in AISI 310S steel exposed to high-cycle fatigue. A 2.2 times increase in the fatigue life of samples irradiated by electron beams was revealed. The outcomes of scanning and transmission electron microscopic studies suggest the most probable reason for the fracture of steel samples irradiated by a high-intensity electron beam to be microcraters originating on a treated surface and acting as stress risers initiating the propagation of microcracks. The irradiation with a pulsed electron beam causes extremely fast melting of the surface. As a result of the subsequent rapid crystallization, a polycrystalline structure nearly twice as small as an average grain in the untreated steel is formed. Since a surface layer crystallizes rapidly, crystallization cells ranging from 120 to 170 nm develop in the volume of grains. The fatigue testing is shown to be associated with a martensite transformation γ ⇒ ε in the surface layer. One option to intensify a fatigue life increase of the steel in focus is supposed to be the neutralization of crater-forming on a surface treated by electron beams.

scholarly journals STAINED PECTIN AS SEEN IN THE ELECTRON MICROSCOPE

1960 ◽  
Vol 8 (2) ◽  
pp. 501-506 ◽  
Author(s):  
Peter Albersheim ◽  
K. Mühlethaler ◽  
A. Frey-Wyssling
Keyword(s):  
Middle Lamella ◽  
Water Soluble ◽  
Hot Water ◽  
Residual Fraction ◽  
Young Plant ◽  
Pectic Substance ◽  
Electron Microscopic ◽  
Dense Deposits ◽  
Longitudinal Wall ◽  
Microscopic Studies

This paper describes electron microscopic studies on the distribution of pectin within young plant cells. Dark-grown onion roots, from 1 to 3 mm. in length, were used. In order to make the pectic substances selectively dense to electrons, they were first reacted with basic hydroxylamine. This treatment produces pectic hydroxamic acids, which in turn were treated with ferric ion to form insoluble complexes. The tissue was imbedded, sectioned, and then observed by electron microscopy. Dense deposits of iron were found in the region of the middle lamella and in a second area near the surface of the primary wall. Transverse walls of varying maturity were noted. The pectin of the more frequent, immature cross-walls, leads directly into the inner reacting layer of the axillary (longitudinal) wall. The pectin of the more mature transverse walls becomes, on the other hand, intimately associated with the middle lamella pectin of the axillary wall. It is shown that the pectin of the middle lamella represents the hot water-soluble portion of the pectic substance, while the internal layer of the axillary wall and the transverse wall pectin represent the so called residual fraction. Hot versene extraction removes essentially all electron-dense material.

scholarly journals Cytoskeletal organization of axons in vertebrates and invertebrates

2020 ◽  
Vol 219 (7) ◽  
Author(s):  
Andreas Prokop
Keyword(s):  
Initial Segment ◽  
Growth Cones ◽  
Axon Initial Segment ◽  
Electron Microscopic ◽  
Cytoskeletal Organization ◽  
Ultrastructural Studies ◽  
Microscopic Studies ◽  
Different Dimensions ◽  
Plastic Changes ◽  
Axon Initial Segments

The maintenance of axons for the lifetime of an organism requires an axonal cytoskeleton that is robust but also flexible to adapt to mechanical challenges and to support plastic changes of axon morphology. Furthermore, cytoskeletal organization has to adapt to axons of dramatically different dimensions, and to their compartment-specific requirements in the axon initial segment, in the axon shaft, at synapses or in growth cones. To understand how the cytoskeleton caters to these different demands, this review summarizes five decades of electron microscopic studies. It focuses on the organization of microtubules and neurofilaments in axon shafts in both vertebrate and invertebrate neurons, as well as the axon initial segments of vertebrate motor- and interneurons. Findings from these ultrastructural studies are being interpreted here on the basis of our contemporary molecular understanding. They strongly suggest that axon architecture in animals as diverse as arthropods and vertebrates is dependent on loosely cross-linked bundles of microtubules running all along axons, with only minor roles played by neurofilaments.

Transmission and Scanning Electron Microscopy of the Follicle in the Human Ovary

1974 ◽  
Vol 32 ◽  
pp. 142-143
Author(s):  
I. M. Baccarini
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Granulosa Cells ◽  
Osmium Tetroxide ◽  
Human Ovary ◽  
Scanning Microscope ◽  
Electron Microscopic ◽  
Ultrastructural Studies ◽  
Microscopic Studies ◽  
Scanning Electron

Several ultrastructural studies demonstrated that the granulosa cells changed the structure since their differentiation, maturation and degeneration. However, little is known about the organization of the granulosa cells in the follicle for instance, the connection between the cells and cellular interchanges.Fragments of ovary obtained from the surgery room were fixed in 3% buffered glutaraldehyde for scanning microscope and post-fixed in 1% buffered osmium tetroxide for electron microscopic studies.

Ultrastructural Studies of the Femoral Tendon Cells in the Freshly Molted Cockroach Nymph

1969 ◽  
Vol 27 ◽  
pp. 254-255
Author(s):  
Martin Hagopian ◽  
David Spiro
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscopic ◽  
Ultrastructural Studies ◽  
Leucophaea Maderae ◽  
Large Numbers ◽  
Secretion Granules ◽  
Tendon Cells ◽  
Microscopic Studies ◽  
Characteristic Features ◽  
Oriented Parallel

In our electron microscopic studies of the freshly molted cockroach, Leucophaea maderae, the tendon (epidermal) cells in the nymph's femur show some characteristic features which have hitherto not been described. Within an hour of ecdysis the majority of tendon cells are attached to the cuticle and adjacent tendon cells; others are joined to the cuticle on one side and fastened to muscle on the opposite side; and some are apparently migrating free in the hemolymph. The tendon cells, whether adjacent to the cuticle or within the hemolymph, display very large numbers of microtubules and also have regions which contain rough endoplasmic reticulum and secretion granules (Fig. 1). The microtubules are oriented parallel to the myofilaments in underlying muscle cells.

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