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an instrument for obtaining thin sections from pieces of organs and tissues that have been frozen or coated with paraffin or pyroxylin for examination under a microscope. The first microtome was built in the first half of the 19th century by the German biologist A. Oschatz, a co-worker of J. Purkyně.
There are two kinds of microtomes. In the first type, the object is fixed in a holder and is raised by means of a micrometer screw, and the microtome knife moves horizontally (sled microtome). In the second type, the object moves and the knife is fixed. To produce sections of unprepared tissues that are to be examined immediately (for example, during surgical operations when histological analysis is urgently required), a freezing microtome is used; in this case the piece of tissue is frozen in an aqueous or saline solution by means of liquid carbon dioxide. The thickness of the sections produced by a microtome from substances coated with paraffin is 1–2 microns (μ); for substances coated with pyroxylin, 10–12 μ; and for frozen substances, not more than 10 μ. A special version of the microtome, called an ultramicrotome, is used to produce very thin sections (down to 200 angstroms) for examination under an electron microscope.
REFERENCESRomeis, B. Mikroskopicheskaia tekhnika. Moscow, 1954. (Translated from German.)
Borrmann, H. “Mikrotome in Wissenschaft und Forschung.” In Medizintechnik. Berlin, 1958. Pages 102–112.
S. IA. ZALKIND