Redistribution of Squamous and Columnar Epithelium After Gastric Mucosal Wounds in the Rat

&NA; Superficial (epithelial) and deep (full mucosal) wounds were produced across the squamo‐columnar junction of the stomach of the rat, in three positions relative to the junction. When the wound included equal areas of the two sorts of mucosa, healing restored the junction to its original position irrespective of the depth of wounding. When predominantly glandular mucosa was damaged, wounds of both depths healed with deviation of the junction towards the glandular area. However, when predominantly squamous mucosa was damaged, healing resulted in deviation of the junction into the squamous part of the stomach when the wounds were deep, but in return of the junction to its original position when the wounds were superficial. This difference between the effects of superficial and deep wounding was confirmed by experiments in which the wall of the stomach in the junctional area to be damaged had previously been rotated surgically through 90 degrees. These results suggested that in deep wounds involving the whole of the mucosa, the rate of migration of the two types of epithelium was the principal factor determining the final distribution of the two distinct sorts of mucosa, but that in superficial wounds the residual mesenchyme of the lamina propria, at least on the squamous side, influenced the type of epithelial cells which migrated across it and became established over it. It is therefore postulated that in some tissues subepithelial mesenchyme plays an important role in determining the pattern of the regenerated mucosa which develops following injury.