Gene Mapping to Chromosomes by Hybridization in Situ

Since the technique of hybridizing labeled nucleic acid sequences to cytological preparations (hybridization in situ) was first described in 1969 by Pardue and Gall (1 ), it has undergone considerable refinement. In those early days, the technique was only capable of detecting and locating highly repeated target sequences such as satellite DNAs (2 ) or the genes for ribosomal DNA (3 ).