CYTOCHEMICAL-LOCALIZATION OF CYTOCHROME-C-OXIDASE ACTIVITY IN MITOCHONDRIA IN THE TEGUMENT AND TEGUMENTAL AND PARENCHYMAL-CELLS OF THE TREMATODES ECHINOSTOMA-TRIVOLVIS, ZYGOCOTYLE-LUNATA, SCHISTOSOMA-MANSONI, FASCIOLA-GIGANTICA AND PARAGONIMUS-OHIRAI

Cytochrome c oxidase in the mitochondria of the tegument and tegumenta l and parenchymal cells was examined cytochemically in Echinostoma tri volvis, Zygocotyle lunata, Schistosoma mansoni, Fasciola gigantica and Paragonimus ohirai, trematodes that inhabit different sites in their vertebrate hosts. Clear differences in enzyme activity occurred in the mitochondria of these species, probably reflecting the different ener gy metabolisms of these worms. Marked aerobic metabolism occurred in S . mansoni and P. ohirai adults that inhabit the host mesenteric veins and the lungs, respectively. The tegument and parenchymal cells of S. mansoni possess relatively few, small mitochondria with tubular crista e which are heavily reactive for cytochrome c oxidase. In P. ohirai, t he activity for cytochrome c oxidase in tegumental mitochondria increa sed gradually from juveniles to adults, reflecting that the respirator y activity increased with growth and the aerobic metabolism is activat ed when the worms reach the lung. P. ohirai juveniles and adults had t wo types of mitochondria with different shapes and enzyme activities t hat were located in two different types of parenchymal cells. The inte stinal species, E. trivolvis had mitochondria in the basal aspect of t he tegument, and some variations in enzyme activity of their mitochond ria in the tegumental and parenchymal cells were observed, suggesting that they possess both aerobic and anaerobic metabolic systems. Z. lun ata that live in rodent caeca are devoid of mitochondria in the tegume nt and have many characteristic mitochondria with undeveloped cristae in the parenchymal cells. Mitochondria of F. gigantica showed weak or no activity for cytochrome c oxidase, suggesting that the worm is well -adapted to an anaerobic environment in the host bile duct.