Perlecan and Heparanase Localization in Hertwig's Epithelial Root Sheath during Root Formation

Cementogenesis starts with the differentiation of dental follicular cells into cementoblasts. In this process, the invasion of dental follicular cells into the chinks of the ruptured Hertwig's Epithelial Root Sheath (HERS) is considered to be a key factor. However, little is known about the mechanisms involved in degradation of the basement membrane surrounding HERS. Perlecan is one of the main basement membrane heparan sulfate (HS) proteoglycans. When root formation progresses, perlecan becomes scarce on the basement membrane of HERS. In contrast, HERS cells show intense labeling for heparanase that cleaves HS chains in perlecan. These results indicate that heparanase secreted by the cells of HERS may contribute to root and periodontal tissue formation by degrading perlecan in the basement membrane of HERS.