To some extent, brightfield microscopy is used in most disciplines requiring microscopic investigation.
Because it is a simple method, this is the first type of microscopy students learn in schools.
The life sciences, particularly microbiology and bacteriology, have always relied on the brightfield technique.
This technique can be used to view fixed specimens or live cells. Since many organic specimens are transparent or opaque, staining is required to cause the contrast that allows them to be visible under the microscope.
Different stains and staining techniques are used depending upon the type of specimen and cell structure being examined. For example
Fuchsin is used to stain smooth muscle cells
Methylene blue is used to stain cell nuclei
Gram stain is used on bacteria and gives rise to the name gram-negative or gram-positive bacteria based on the reaction of the bacteria to the stain. In fact, many scientific journals will not accept microbiological research for publication that is not supported by gram staining and brightfield illumination methodology. Most routine medical microscopic examination of blood and tissue is performed using this illumination technique.
Different complimentary techniques can be used to augment brightfield microscopy. By using a polarizing filter this illumination technique can be used in geological microscopic research and will reveal details not visible using white light.
Properly stained, microorganisms may be magnified to 1200x; utilizing an oil immersion objective will increase resolution at this high magnification.
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