A STUDY OF THE PROLIFERATIVE ACTIVITY OF THE LONG JUNCTIONAL EPITHELIUM USING ARGYROPHILIC NUCLEOLAR ORGANIZER REGION (AGNORS) STAINING

The proliferative activity of the long junctional epithelium (LJE) in rats was examined using stains for argyrophilic proteins of the nucleo lar organizer region (AgNORs protein). The LJE was experimentally prod uced by insertion of a rubber piece between maxillary molars for 1 wk. After removal of the rubber, the length and AgNORs parameters of the LJE were measured and analyzed statistically. The LJE widely covered t he apical side of the exposed root surface 4 wk after the removal. Its length was longest after 4 and 8 wk; it became shorter subsequently. The AgNORs were visible as black dots of various sizes and numbers on the sections. A high potential for proliferation was obvious in the LJ E after 4 wk and was maintained until 12 wk after the removal. The AgN ORs ratio on the connective tissue interface of the LJE was about twic e of that of normal junctional epithelium after 4-12 wk. The prolifera tive activity on the root surface side was slightly increased after 4 wk. There was no significant difference in proliferative activity betw een the coronal and apical sides. These results suggest that the proli ferative activity of the LJE is maintained continuously at a high leve l on the connective tissue interface supplying the epithelial cells. B asal cells proliferate at the connective tissue interface of the LJE, migrate directly to the root surface or via the apical portion and fin ally desquamate from the surface of the epithelium.