The usual methods of microscopical examination are based on observing the specimen in the light transmitted or reflected by it. Fluorescence microscopical preparations are self-luminous. In most biological preparations the tissue sections are stained with a fluorochrome, a dye that emits light of longer wavelength when exposed to blue or ultraviolet light. The fluorescing parts of the stained object then appear bright against a dark background. The staining techniques are extremely sensitive and can often be used in living materials. See Chronology, 1970, Caspersson, Zech, and Johansson.
Subjects: Chemistry — Genetics and Genomics.