A rapid and simplified technique for analysis of archival formalin-fixed, paraffin-embedded tissue by fluorescence in situ hybridization (FISH).

We here present a simplification of the entire procedure for preparing formalin-fixed, paraffin-embedded tissue to be used for FISH-analysis. The steps for deparaffinisation and disintegration of the tissue to produce intact cell nuclei in a monodispersed suspension are detailed as well as the hybridisation steps. The procedure results in a clear cell suspension with intact cell nuclei and without clumped debris particles. The enzymatic digestion is restricted to the trypsinisation step of the deparaffinisation procedure. No further pretreatments prior to hybridization are performed. This modified technique has been successfully applied to different formalin-fixed, paraffin-embedded materials.