Expecting to only perform a western blot in Dr. Baldari's lab on Tuesday, I was surprised when one of the undergraduate students took us to observe the various microscopes. The microscopes were kept in the basement to minimize vibrations from the building and the environment. I was shocked when I heard the purchase price of the microscopes. I'm talking about $500,000! One of the microscopes that particularly interested me was the Transmission Electron Microscope (TEM). TEM can magnify objects up to 600,000x! Unlike the light microscope, TEM uses monochromatic (light from a single wavelength) electrons instead of light to magnify objects. Electrons are emitted into a vacuum until they reach electromagnetic lenses. These lenses focus the electrons into a thin beam that reflects and transmits through the specimen. The electrons that transmit through the specimen hit a florescent screen. The image that appears contains different shades of color depending on the density of the specimen. The darker areas of the image represent fewer electrons transmitted through the specimen.
TEM can be used to analyze a variety of sample including samples from medical and biological sciences. For example, TEM can be used to observe the morphological changes of human tissues when treated with drugs. Tissue samples have to be cut into extremely thin sections to be viewed by this microscope. The size requirement for TEM is actually an advantage for researchers who have difficulty obtaining samples in the first place.
References
Intertek Northwest Technology Centre. GLP Tissue Microscopy. http://www.intertek-cb.com/ nwtc/biotemlab.shtml (accessed June 28, 2009).
Nobel Prize in Physics. The Transmission Electron Microscope. http://nobelprize.org/educational_ games/physics/microscopes/tem/index.html (accessed June 28, 2009).
University of Nebraska. Transmission Electron Microscope (TEM). http://www.unl.edu/CMRAcfem /temoptic.htm (accessed June 28, 2009).
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