Abstract
Cationized ferritin (CF) was topically applied to the rat gingival sulcus (GS) after hyaluronidase (HY) treatment to investigate morphologically neutrophil responses to foreign substances.
The tracer could enter into only the junctional epithelium (JE) close to GS and did not penetrate it deeply. Thus, HY did not increase the permeability of the tracer into the JE but induced marked neutrophil infiltration into the GS. In other words, HY appeared to act as a chemotactic factor for neutrophils rather than a factor that opens the intercellular spaces of the JE.
In neutrophils close to the GS which prominently took up CF by phagosomes, the peroxidase-positive azurophil granules were fused with the CF containing-phagosomes, and the granular contents were intracellularly released into the phagosomes. The part of the phagocytosed CF appeared to be digested in the phagosomes, whereas, the extracellular release of the specific granules was not observed.
These findings suggest that the foreign substances in the GS are killed and digested by the intracellular release of neutrophil azurophil granules into the phagosomes, namely their intracellular release without impairing the adjacent gingival tissue constituents the first defense line in the GS against invading microbes.
