Transport pathway and uptake of microperoxidase in the junctional epithelium of healthy rat gingiva.

Abstract

Junctional epithelial uptake and transport of microperoxidase (MP, heme‐undecapeptide) was investigated in the healthy gingivae of 24–26 day old rats. MP products were observed from the blood vessels in the junctional epithelium to the internal basement lamina (IBL) close to enamel surface via the intercellular spaces of junctional epithelial (JE) cells. The IBL was strongly stained with MP, but there was an abrupt stoppage of MP at the external basement lamina (EBL). The EBL seemed to act as a barrier against transport of MP from the gingival connective tissue into the junctional epithelium. MP was also found in the micropinocytotic vesicles and phagocytotic vacuoles of innermost JE cells. Neutrophils located in the intercellular spaces of JE cells showed positive reaction for both MP and/or endogenous peroxidase. These results suggest that gingival fluid is probably transuded from the blood vessels into the junctional epithelium, reaches the IBL via the intercellular spaces, and diffuses into the oral environment along the IBL, and that toxic and foreign materials are taken up by the micropinocytotic vesicles and phagocytotic vacuoles of JE cells and the neutrophils on their way to the oral environment.