[Difference in uptake of junctional epithelium using microperoxidase and horseradish peroxidase as tracers in healthy rat gingiva].

Abstract

A microperoxidase (MP, molecular weight 1,900; molecular diameter 20 A) or a horseradish peroxidase (HRP, molecular weight 40,000; molecular diameter 40 A) was intravenously injected into healthy rat junctional epithelium (JE) to investigate the endocytosis of foreign substances. By light microscopy, intravenous HRP was taken up throughout the JE, and the uptake was marked at the coronal portion of the JE. On the other hand, MP was taken up by only the coronal portion of the JE. At the electron microscopic level, the tracers were taken up by endocytotic organellae (phagosomes and micropinocytotic vesicles) of junctional epithelial cells (JE cells). HRP-positive endocytotic organellae in the JE cells were more numerous than MP-positive organellae. Thus, JE, especially its coronal portion, exhibited strong endocytotic activity for HRP compared with that for MP. These findings suggest that the JE has selective endocytotic ability for foreign substances, and plays an important role in protecting periodontal tissue.