Localization of peroxidase activity in tegumental, muscle, and parenchymal cells of the lung fluke Paragonimus miyazakii (Digenea: Troglotrematidae).

The distribution and localization of peroxidase activity were examined in adults of Paragonimus miyazakii in sections stained with 3,3'-diaminobenzidine in the presence of hydrogen peroxide. Peroxidase activity was detected in tegumental cell mitochondria. With cell development, the reaction intensity became greater. Activity extended from the inner membrane (undifferentiated stage) to the intermembrane space (differentiating stage) and then to the matrix (differentiated stage). Mitochondria with the most intense reaction were densely distributed in the outer syncytial region. Strong activity was also present in mitochondria of muscle cells and in those of Type II parenchymal cells. Intermembrane spaces were the predominant site of this activity. Characteristically, both 10 mM azide and 1 mM cyanide were mildly effective in the inhibition of mitochondrial peroxidase activity in each cell type.