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skos:definition |
UMD: Electron microscopes designed to operate like light microscopes, except that that they use an electron beam instead of light to magnify an image, allowing greater magnification and resolution than a light microscope. Transmission electron microscopes (TEMs) consist of an electron gun and vacuum chamber, an electromagnetic condenser and imaging electromagnetic (lens) systems, a specimen chamber, a viewing chamber and fluorescent screen, and photographic and vacuum systems. Before observation, tissue samples must be fixed, processed, embedded, sectioned, mounted on a support stub, and usually coated (e.g., using a sputter coater) with a thin film of a heavy metal (e.g., gold). TEMs allow highly detailed (e.g., 500,000x magnification) visualization of tissue, individual cells, and cell structures; they are frequently used to identify types of microorganisms (viruses and bacteria) in medical specimens, as well as specific cell types in biopsy samples.,NCI: An electron microscope that transmits a beam of elec
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