Epithelial mitotic activity in experimental gastric wounds.

Excision wounds were made in the pyloric epithelium of the rat's stomach and the mitotic response studied at intervals from 1 day to 12 weeks afterwards. Increased mitotic activity followed wounding with peaks at 2 and 7 days, and with a subsequent high level of activity which was maintained in all the later stages of healing, even in the presence of long-delayed epithelialization. Most mitoses initially occurred some distance from the wound edge, but subsequently the highest counts were found in glands immediately adjacent to the edge, and this distribution persisted. Mitotic counts for deep ulcers (including mucous membrane and muscularis externa) were higher than those for superficial ulcers (involving mucous membrane only) at any one time.