Observation of E. coli O157:H7 densely packed micro-colonies on ovine (A) and bovine (B) terminal rectum explants as visualised by confocal microscopy. Dapi (blue) = nuclei. FITC (green) = E.coli O157. (C) and (D) are uninfected ovine and bovine terminal rectum explants, respectively. E. coli O157:H7 was incubated with explants for 8 h with changing of the media occurring every hour after the first 2 h. Bar (A) = 32.17 μm, (B) = 27.5 μm, C = 49.26 μm, D = 31.77 μm.