Neutrophils in the molar tooth extraction wound in the rat: a transmissionelectron microscope (TEM) study

Neutrophils have been ascribed a number of functions from ultrastructural s tudies of healing wounds. All of the wounds so far examined have been relat ively aseptic. This study investigates, by TEM, the structure of neutrophil s in healing molar tooth sockets in rats. Prior to epithelial coverage, a d ense infiltrate of neutrophils separated the viable wound tissues from the overlying debris and bacteria. The more deeply situated neutrophils contain ed many granules and only occasional phagosomes. More superficial neutrophi ls contained fewer granules and phagosomes with engulfed bacteria undergoin g lysis. The most superficial neutrophils were degenerate, lacked granules and often contained viable bacteria. There were varying numbers of neutroph ils containing granules in the blood clot, granulation tissue, wound epithe lium and adjacent tissue. No extracellular neutrophil granules nor extracel lular discharge of granules was found. These findings differ from those of previous ultrastructural studies of relatively aseptic healing wounds. Ultr astructurally, the only function of neutrophils in healing tooth extraction wounds appears to be phagocytosis of bacteria, which supports a role in th e prevention of infection.