I am struggling with The XL DLEU/TP53 locus-specific probe (metasystem) detects deletions in the long arm of chromosome 13 and in the short arm of chromosome 17 in Chronic lymphocytic leukemia (CLL) by FISH
1) Usually you get both on your slide, adherent cells without synchronisation gives around 2-3% of metaphase spreads, rest is interphase nuclei, so for a good statistics use as much cells as possible. Your protocol suggest, that for your purpose [detection of deletion] interphase nucleus is enough.
2) You need to detach cells, fix them in suspension [we use MtOH: Acetic acid 3:1 after hypotonic treatement- just spin the cells and change solution for fixative] and than put a drop [30ul?] of cells in fixative on clean slide from a few cm distance [10?:)]. Let it dry. Its adviced to make slides at least a day before fish procedure. You can always check how dense they are [regular phase contrast should do]. I havent found any good protocol for keeping cells attached during protocol, however i was aiming for metaphase spreads, so maybe in your case you could leave them attached?
3) Your protocol is somehow a bit simple, if it doesnt work I can provide with our protocol [but for suspension cells].