Fig. 5.

Scanning electron photomicrograph of colon from calf 7 days after oral inoculation with strain 84-5406. The mucosal surface is roughened due to rounding and detachment of enterocytes, and diffuse bacterial attachment to the apical surfaces of these cells. Microvilli are visible; an individual enterocyte that has undergone rounding and is in the process of detachment is denoted by an arrow. Ridges (r) have atrophied due to cell loss, and in this figure are approximately one-half the width of that of the control calf. Furrows (f) demarcate boundaries of ridges, as in the control (original negative magnification ×500; bar = 20 μm).