The Fine Structure of the Sheath of Volvox Carteri f. Weismannia

1977 ◽  
Vol 35 ◽  
pp. 346-347
Author(s):  
Regina Birchem
Keyword(s):  
Developmental Stages ◽  
Ruthenium Red ◽  
Sulfated Polysaccharides ◽  
Volvox Carteri ◽  
High Voltage Electron Microscopy ◽  
Ultrastructural Studies ◽  
Voltage Electron ◽  
Sheath Formation ◽  
And Inversion ◽  
Sheath Material

Spheroids of the green colonial alga Volvox consist of biflagellate Chlamydomonad-like cells embedded in a transparent sheath. The sheath, important as a substance through which metabolic materials, light, and the sexual inducer must pass to and from the cells, has been shown to have an ordered structure (1,2). It is composed of both protein and carbohydrate (3); studies of V. rousseletii indicate an outside layer of sulfated polysaccharides (4).Ultrastructural studies of the sheath material in developmental stages of V. carteri f. weismannia were undertaken employing variations in the standard fixation procedure, ruthenium red, diaminobenzidine, and high voltage electron microscopy. Sheath formation begins after the completion of cell division and inversion of the daughter spheroids. Golgi, rough ER, and plasma membrane are actively involved in phases of sheath synthesis (Fig. 1). Six layers of ultrastructurally differentiated sheath material have been identified.

Staining Serial Thick Sections For High-Voltage Electron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 708-709
Author(s):  
John C. Kinnamon ◽  
Terri A. Sherman
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Carbon Coating ◽  
Three Dimensional ◽  
Taste Bud ◽  
Serial Sections ◽  
High Voltage Electron Microscopy ◽  
Ultrastructural Studies ◽  
Voltage Electron ◽  
High Voltage Electron

Ultrastructural studies often require three-dimensional reconstructions from serial electron micrographs. The use of thick sections and high voltage electron microscopy can reduce the numbers of serial sections needed, but we have found that over 300 serial sections (0.5 μm thick) are still needed for our studies of taste bud ultrastructure. Serial reconstructions are almost always done with sections mounted onto formvar-coated slot grids, because they provide an unobscured view of the specimen. Staining and carbon coating several hundred formvar-coated slot grids often results in the loss of serial sections because the formvar films break due to handling during the staining and carbon-coating procedures. In addition, the staining process itself can be tedious and time-consuming when staining thick sections because staining times of hours are often required. Such lengthy staining times may result in staining artifacts due to exposure of the stain to the atmosphere, especially with lead stains.

High Voltage Electron Microscopy for Thick Sections of Biological Materials Combined with Molecular Tracers

1972 ◽  
Vol 30 ◽  
pp. 480-481
Author(s):  
Eichi Yamada ◽  
Harunori Ishikawa
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Biological Materials ◽  
Ruthenium Red ◽  
Mouse Kidney ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Structural Details ◽  
Molecular Tracers

One of the advantages of high voltage electron microscopy (HVEM) is the great penetration of electron beam, which permits the examination of thicker sections of resin-embedded biological materials. However, when stained thick sections are examined under the HVEM, all structural details within the whole thickness are brought into focus as superimposed image. Hence, certain structures are not easily observable on such an image, even on the stereo view obtained by specimen tilting technique. To overcome this difficulty, molecular tracers are introduced to the HVEM in an attempt to visualize certain structures selectively.Mouse kidney and cardiac muscle were examined using ruthenium red and peroxidase as molecular tracers. Thick Epon sections ranging from 0.5 to 3 μ were observed in a JOEL JEM-1000 or a Hitachi HU-1000 HVEM, with an accelerating voltage of 1000 KV. Pictures were taken routinely as stereo pairs using a tilting stage device with ±10° or ±8°.

High Voltage Electron Microscopy of Ion-Milled Dental Enamel

1974 ◽  
Vol 32 ◽  
pp. 60-61
Author(s):  
L. D. Ackerman ◽  
S. H. Y. Wei
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Third Molar ◽  
Polarized Light ◽  
Dental Enamel ◽  
Longitudinal Section ◽  
Ion Milling ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron

Mature human dental enamel has presented investigators with several difficulties in ultramicrotomy of specimens for electron microscopy due to its high degree of mineralization. This study explores the possibility of combining ion-milling and high voltage electron microscopy as a means of circumventing the problems of ultramicrotomy.A longitudinal section of an extracted human third molar was ground to a thickness of about 30 um and polarized light micrographs were taken. The specimen was attached to a single hole grid and thinned by argon-ion bombardment at 15° incidence while rotating at 15 rpm. The beam current in each of two guns was 50 μA with an accelerating voltage of 4 kV. A 20 nm carbon coating was evaporated onto the specimen to prevent an electron charge from building up during electron microscopy.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain

1977 ◽  
Vol 35 ◽  
pp. 570-571 ◽  
Author(s):  
Lee D. Peachey ◽  
Clara Franzini-Armstrong
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Three Dimensional ◽  
Biological Tissues ◽  
High Voltage Electron Microscopy ◽  
Transverse Tubular System ◽  
Peroxidase Reaction ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
T System

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.

Radiation-Induced Precipitation at Thin Foil Surfaces in Ni-Be Alloys

1982 ◽  
Vol 40 ◽  
pp. 598-599
Author(s):  
T. Mukai ◽  
T. E. Mitchell
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Electron Irradiation ◽  
High Vacuum ◽  
Thin Foil ◽  
Homogeneous Precipitation ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Radiation Induced

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.

Some Biological Applications of High Voltage Electron Microscopy

1974 ◽  
Vol 32 ◽  
pp. 298-299
Author(s):  
Hans Ris
Keyword(s):  
High Voltage ◽  
Chromosome Structure ◽  
Nerve Fibers ◽  
Good Resolution ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
University Of Wisconsin ◽  
High Voltage Electron ◽  
One Year ◽  
The University

The High Voltage Electron Microscope Laboratory at the University of Wisconsin has been in operation a little over one year. I would like to give a progress report about our experience with this new technique. The achievement of good resolution with thick specimens has been mainly exploited so far. A cold stage which will allow us to look at frozen specimens and a hydration stage are now being installed in our microscope. This will soon make it possible to study undehydrated specimens, a particularly exciting application of the high voltage microscope.Some of the problems studied at the Madison facility are: Structure of kinetoplast and flagella in trypanosomes (J. Paulin, U. of Georgia); growth cones of nerve fibers (R. Hannah, U. of Georgia Medical School); spiny dendrites in cerebellum of mouse (Scott and Guillery, Anatomy, U. of Wis.); spindle of baker's yeast (Joan Peterson, Madison) spindle of Haemanthus (A. Bajer, U. of Oregon, Eugene) chromosome structure (Hans Ris, U. of Wisconsin, Madison). Dr. Paulin and Dr. Hanna are reporting their work separately at this meeting and I shall therefore not discuss it here.

An Environmental Wet Cell For High Voltage Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 18-19
Author(s):  
N.J. Tighe ◽  
H.M. Flower ◽  
P.R. Swann
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Image Quality ◽  
Inelastic Scattering ◽  
High Voltage ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Environmental Cell ◽  
Water Saturated ◽  
High Temperature Gas

A differentially pumped environmental cell has been developed for use in the AEI EM7 million volt microscope. In the initial version the column of gas traversed by the beam was 5.5mm. This permited inclusion of a tilting hot stage in the cell for investigating high temperature gas-specimen reactions. In order to examine specimens in the wet state it was found that a pressure of approximately 400 torr of water saturated helium was needed around the specimen to prevent dehydration. Inelastic scattering by the water resulted in a sharp loss of image quality. Therefore a modified cell with an ‘airgap’ of only 1.5mm has been constructed. The shorter electron path through the gas permits examination of specimens at the necessary pressure of moist helium; the specimen can still be tilted about the side entry rod axis by ±7°C to obtain stereopairs.

High-voltage electron microscopy of maxillary gland of spirochete-infected brine shrimp: lesion of efferent tubule

1988 ◽  
Vol 46 ◽  
pp. 362-363
Author(s):  
G. E. Tyson ◽  
M. J. Song
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Brine Shrimp ◽  
Natural Populations ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Infected Adult

Natural populations of the brine shrimp, Artemia, may possess spirochete- infected animals in low numbers. The ultrastructure of Artemia's spirochete has been described by conventional transmission electron microscopy. In infected shrimp, spirochetal cells were abundant in the blood and also occurred intra- and extracellularly in the three organs examined, i.e. the maxillary gland (segmental excretory organ), the integument, and certain muscles The efferent-tubule region of the maxillary gland possessed a distinctive lesion comprised of a group of spirochetes, together with numerous small vesicles, situated in a cave-like indentation of the base of the tubule epithelium. in some instances the basal lamina at a lesion site was clearly discontinuous. High-voltage electron microscopy has now been used to study lesions of the efferent tubule, with the aim of understanding better their three-dimensional structure.Tissue from one maxillary gland of an infected, adult, female brine shrimp was used for HVEM study.

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