fluorescence in situ hybridization
(floor-EH-sents in SY-too HY-brih-dih-ZAY-shun)
A technique used to identify the presence of specific chromosomes or chromosomal regions through hybridization (attachment) of fluorescently-labeled DNA probes to denatured chromosomal DNA. Examination through a microscope under fluorescent lighting detects the presence or absence of the colored hybridized signal, hence the presence or absence of the chromosome material. Also called FISH.