Electron microscopy of acid phosphatase in the exudate from inflamed gingivae

An ultrastructural study on human gingival fluid made it possible to localize acid phosphatase in polymorphonuclear leucocytes, bacteria and to a lesser degree in histiocytes. The polymorphonuclear leucocytes with autophagic bodies, and the histocytes contained intact and ruptured lysosomes as well as phagocytic vacuoles with engulfed bacteria. The surface of leucocyte cell membranes sometimes presented a positive enzymatic reaction. Large bodies, rich in acid phosphatase were observed in mast cells. In the epithelial cells scattered fine lead precipitates were noted and the epithelial nuclei sometimes reacted positively. In Gram positive bacteria, acid phosphatase was localized between the cytoplasmic membrane and the cell wall, whereas in Gram negative bacteria a positive reaction was observed in the outer layers of the cell wall. Bacteria without cell walls were surrounded by a lead precipitate. In addition, lead stainings were located in the bacterial cytoplasm. The major acid phosphatase activity seemed to be related to the leucocytes and the micro‐organisms.