Figure 4 Corrosion casting and scanning electron microscopy (SEM) of the colonic mucosal plexus. The microcirculation was casted 4 days after the intrarectal instillation of (A) vehicle control, or (B) 2,4,6‐trinitrobenzenesulphonic acid antigen (bar = 50 μm). In both conditions, the circulation was flushed and fixed before the infusion of low viscosity methyl methacrylate (Mercox). The surrounding tissue was corroded away and the resulting luminal cast was imaged using 3D (tilt‐angle) SEM.