(flor-EH-sense in SIT-tyoo hy-bru-duh-ZAY-shun) An important laboratory test used to help doctors look for chromosomal abnormalities and other genetic mutations. Fluorescence in situ hybridization, also called FISH FISH: See fluorescence in situ hybridization. , directs colored light under a microscope at parts of chromosomes chromosomes: The part of the cell that contains our DNA or genetic code. or genes. Missing or rearranged chromosomes are identified using FISH.
