Slide 1 (113)
Gross: Acute bacillary dysentery showing diffuse ulceration of mucosa. The greenish-yellow foci are remnants of partially necrotic mucosa. The mucosa may finally reepithelialize with regeneration of the normal villous pattern. Since the damage is limited to the mucosa, this disease does not result in stricture.

Slide 2 (113)
Lower power: Small bowel. The glands have almost disappeared and only the basal portions can be recognized. The mucosa is now composed of necrotic tissue covered with a fibrinous pseudomembrane. A true membrane overlies normal tissue. A pseudomembrane consists of necrotic tissue which after removal leaves an ulcerated surface.