Plaque—Neutrophil Interaction in Monoinfected Rats as Visualized by Transmission Electron Microscopy

Rats monoinfected with Actinomyces naeslundii contain massive interdental bacterial plaques which are partically covered by a concentration of PMNLS. The neutrophils are massed in the form of a pseudoepithelial barrier several cell layers thick with narrow intercellular spaces. The PMNL barrier appears to prevent bacterial invasion of the underlying gingiva. Phagocytosis and killing of bacteria occurs at the interface between the plaque and the PMNL barrier. The protective as well as possible detrimental effects of PMNL concentrations are discussed in terms of tissue destruction in periodontal disease.