Other light microscopes. In addition to the familiar compound microscope, microbiologists use other types of microscopes for specific purposes. These microscopes permit viewing of objects not otherwise seen with the light microscope. An alternative microscope is the dark-field microscope, which is used to observe live spirochetes, such as those that cause syphilis. This m icroscope contains a special condenser that scatters light and causes it to reflect off the specimen at an angle. A light object is seen on a dark background. A second alternative microscope is the phase-contrast microscope. This microscope also contains special condensers that throw light “out of phase” and cause it to pass through the object at different speeds. Live, unstained organisms are seen clearly with this microscope, and internal cell parts such as mitochondria, lysosomes, and the Golgi body can be seen with this instrument.
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