Ultramicrotome

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File:Microtome-ultras.jpg
A ribbon of ultrathin sections prepared by room temperature ultramicrotomy, floating on water in the boat of a diamond knife used to cut the sections. The knife blade is the edge at the upper end of the trough of water.

An ultramicrotome is a device which cuts specimens into very thin (30 to 50 nanometer) slices. The specimen is first embedded in a block of rigid material such as wax or epoxy. A glass or diamond knife is then used to cut the specimen. Typically the knife is mounted in a water trough which allows the sample to float in order to be collected for later microscopy.

History

File:Cummings 1774 Microtome.jpg
A diagram of a microtome drawn by Alexander Cummings in 1770.

The microtome itself was invented in 1770 by George Adams, Jr. (1750–1795) and further developed by Alexander Cummings (1733–1814), a Scottish watchmaker.[1] The device was hand-cranked, and advanced a sample for cutting with a metal blade.[2]

In 1835, Andrew Prichard developed a table based model which allowed for the vibration to be isolated by affixing the device to the table, separating the operator from the knife.[3] The metal knives used in microtomes were not suitable for transmission electron microscopy, being too dull to create slices thin enough. In 1950, Harrison Latta and J. Francis Hartmann discovered that the edge of broken glass could be used to cut thin sections of specimen.[4] However, the edge of a glass knife dulls quickly for harder specimens, and in 1954, Humberto Fernández-Morán Villalobos (1924-1999) invented a knife made of diamond for ultramicrotomy.[5]

References

  1. Quekett, John (1848). "Chapter 12: Microtomes and Microtome Knives". In Bailliere, Hippolyte. A Practical Treatise on the use of the Microscope. pp. 306. London, England.
  2. Hill, John (1770). [http://www.archive.org/details/constructiontim00hillgoog The Construction of Timber, from its early growth; Explained by Microscope, and proven from Experiments, in a great Variety of Kinds. pp. 5-11, Plate I. London, England.
  3. Gilbert Morgan Smith: The Development of Botanical Microtechnique. In: Transactions of the American Microscopical Society 34, Nr. 2. 1915, S. 71–129, (PDF-Version of the article)
  4. Latta H, Hartmann J F (June 1950). "Use of a glass edge in thin sectioning for electron microscopy" Proc Soc Exp Biol Med.74 (2): 436–439
  5. Venezuelan Patent