Figure 1. Matrilysin (MMP-7) expression in epithelium of human periodontium. Histological sections were prepared from normal periodontal tissue obtained during therapeutic removal of tooth 24 (A and C) and from a palatal explant tissue cultured on a Millipore filter for 5 days (B and D). Positive reaction with anti-matrilysin antibody (brown, indicated by arrows) can be observed in junctional epithelial cells facing the tooth (A) and in epithelial cell rests of Malassez (C). Suprabasal cells of the explant epibolus at the filter side also reacted with the anti-matrilysin antibody (B; a higher magnification in D). No reaction was detected in connective tissue (CT) in either the gingival tissue or the explant. Neither pocket epithelium (PE) nor infiltrated connective tissue (ICT) of periodontal pocket tissue reacted with matrilysin antibody (E and F).