Myofibroblasts and matrix components in healing palatal wounds in the rat

In order to identify wound contraction and scar formation during palatal mu coperiosteal wound healing in growing rats, the temporal and spatial distri bution of myofibroblasts and matrix components were determined immunohistoc hemically. Myofibroblasts were found in the mucosal part of the palatal wou nd tissue between 4 and 22 days, with the highest density at 8 days post-wo unding. The number of collagen type I and type III fibers gradually increas ed until about 8 days post-wounding, and thereafter the staining intensity of collagen type III decreased. At 60 days post-wounding there were more tr ansversely oriented collagen type I fibers and less type III fibers and ela stin present in the submucosa than in normal tissue. The results suggest th at in this model wound contraction mainly takes place: in the mucosa betwee n 4 and 22 days post-wounding. Furthermore, palatal wounds made in young ra ts heal with distinct scar tissue formation. Therefore, this model is usefu l to test the effects of therapies that aim to reduce wound contraction and scarring after cleft palate surgery.