Ultramicrotome


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ultramicrotome

[¦əl·trə′mī·krə‚tōm]
(engineering)
A microtome which uses a glass or diamond knife, allowing sections of cells to be cut 300 nanometers in thickness.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Ultramicrotome

 

an instrument for cutting extremely thin sections of tissue for examination under an electron microscope.

The motion of the knife or the tissue is strictly regulated at a specific height in order to obtain sections that are usually not thicker than 200 angstroms (A) and are sometimes about 50 A thick. The thickness of a section depends on the quality of the fixing medium and the sharpness of the cutting edge of the knife. In most ultramicrotomes, the knife does not move, and the tissue is moved mechanically or, most often, thermally. The thermal mechanism, which was proposed in 1953 by F. Sjôstrand, operates on the basis of the controlled thermal expansion of the support rod to which the tissue is attached.

The USSR has developed an ultramicrotome based on the thermal mechanism that furnishes sections with a thickness of 50-800 A. Glass and diamond blades are used in ultramicrotomes. The quality of the blades is checked under a dark-field microscope, where the cutting edge of a blade of sufficient quality appears as a bright straight line.

REFERENCES

Elektronnomikroskopicheskie metody issledovaniia biologicheskikh ob”ektov. Moscow, 1963.
Weakley, B. S. Elektronnaia mikroskopiia dlia nachinaiushchikh. Moscow, 1975.
Sjôstrand, F. S. Electron Microscopy of Cells and Tissues, vol. 1. New York-London, 1967.

S. IA. ZALKIND

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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The sections for electron microscopy (50 nm) were obtained using an ultramicrotome (Leica EM UC6 Austria) and were contrasted using a Leica EM AC20 apparatus (Austria) with uranyl acetate and lead citrate solutions (Ultrastain no.
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Sections 400 nm thick were cut using an ultramicrotome (Leica, Germany), stained with 0.5% toluidine blue and viewed with a light microscope.
Thin sections of 100 mm were cut in a Reichert Om U3 ultramicrotome and counterstained with uranyl acetate (45 min, 60[degrees]C) and lead citrate (3 min, 25[degrees]C).
The fixed cuticle was embedded in Epon 618 and 0.500 to 0.6 pm ultrathin sections were cut using a glass knife on an LKB V Ultramicrotome (LKB Company, Bromma, Sweden).
Ultrathin sections of the fibres (50--70 nm) were cut by an ultramicrotome (Leica Ultracut UCT) using diamond knife (Diatome, Leica), stained with Uranyl acetate (EM Sciences)--Lead citrate (Ladd Chemicals, USA) and imaged under the microscope (Hitachi H-600).