Buffer choice and tissue dissection conditions can account for insulator body formation. (A and B) Wing discs from third instar larvae dissected in SFX media, PBS, or Drosophila Ringer’s solution and fixed in <5 min (A) or after a 30-min incubation in nonhumidified conditions (B), stained for CP190 and Mod(mdg4). (C) S2 cells show a similar response after a 30-min incubation in PBS or Ringer’s solution (media controls were kept humidified to prevent evaporation). Bars, 2 µm.