EFFECT OF FIXATION ON INTERPHASE CYTOGENETIC ANALYSIS BY DIRECT FLUORESCENCE IN-SITU HYBRIDIZATION ON CELL IMPRINTS

The direct fluorescent in situ hybridization (FISH) technique using a centromerespecific DNA probe for chromosome 11 was applied on fresh ti ssue imprints from melanomas and pituitary adenomas. The cell imprints were fixed in acetone and formalin, and the influence of fixation was evaluated, Acetone fixed imprints gave a sharp and intense fluorescen t signal in a large number of cells from both tumors without any pretr eatment, In contrast, formalin fixed imprints disclosed a weak hybridi zation signal in a few cells even after careful enzymatic digestion. D irect FISH on acetone fixed cell imprints represents a simple and time saving technique applicable to any laboratory for the study of numeri cal chromosomal abnormalities.