An analysis based on the binding of a fluorescent probe (e.g. DNA or RNA probe) to detect and localize the presence of specific DNA sequences on chromosomes in cloned bacterial or cultured eukaryotic cells.
The procedure of FISH involves the following steps: (1) Preparation of microscopic slide with cells in metaphase of mitosis (2) The slide is treated with a weak base to denature the DNA. (3) A radioactively labeled probe is poured onto the slide. (4) Expose slide to photographic emulsion for a few days or weeks. (5) Develop emulsion.
See also: fluorescence microscopy