BMS 250 Chapter Notes - Chapter 4: Transmission Electron Microscopy, Scanning Electron Microscope, Electron Microscope
Document Summary
Bms (cid:328)(cid:331)(cid:326) chapter (cid:330): biology of the cell. Cells were discovered after microscopes were invented because high magnification microscopes are required to see the smallest human body cells. The dimensional unit often used to measure cell size is the micrometer. One micrometer is equal to (cid:327)/(cid:327)(cid:326),(cid:326)(cid:326)(cid:326) of a centimeter. Microscopy is the use of a microscope to view small scale structures, and it is an invaluable asset in anatomic investigations. The most commonly used instruments are the light microscope, the transmission electron microscope, and the scanning electron microscope. Microscopy samples have no inherent contrast so structures cannot be seen clearly. To provide contrast, colored dye stains are used with light microscope, and heavy metal stains are used with both transmission electron and scanning electron microscopes. The light microscope: produces a two-dimensional image by passing visible light through the specimen. Glass lenses focus and magnify the image as it projected toward the eye.
