Myofibroblasts and matrix components in healing palatal wounds in the rat.

In order to identify wound contraction and scar formation during palatal mucoperiosteal wound healing in growing rats, the temporal and spatial distribution of myofibroblasts and matrix components were determined immunohistochemically. Myofibroblasts were found in the mucosal part of the palatal wound tissue between 4 and 22 days, with the highest density at 8 days post-wounding. The number of collagen type I and type III fibers gradually increased until about 8 days postwounding, and thereafter the staining intensity of collagen type III decreased. At 60 days post-wounding there were more transversely oriented collagen type I fibers and less type III fibers and elastin present in the submucosa than in normal tissue. The results suggest that in this model wound contraction mainly takes place in the mucosa between 4 and 22 days postwounding. Furthermore, palatal wounds made in young rats heal with distinct scar tissue formation. Therefore, this model is useful to test the effects of therapies that aim to reduce wound contraction and scarring after cleft palate surgery.