See fluorescence in situ hybridization fluorescence in situ hybridization: (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, directs colored light under a microscope at parts of chromosomes or genes. Missing… .
