Fig. 1. Fluorescent in situ hybridization of AML-BCR3 (A,A') and ETO-BCR2 (B,B') probes with nuclear halos immobilized on microscopic slides. (A',B') The nuclei were pretreated with RNase A before high-salt extraction. Hybridization signals are presented as black spots (arrows) superimposed on the nuclear halos stained with DAPI.