CYTOCHEMICAL AND BIOCHEMICAL OBSERVATIONS ON DIGESTIVE TRACTS OF DIGENETIC TREMATODES .3. NONSPECIFIC ESTERASE IN HAEMATOLOECHUS MEDIOPLEXUS

The cytochemical localization of nonspecific esterase was investigated in the frog lung fluke, Haematoloechus medioplexus. Fixed or fresh material was incubated in bromoindoxyl acetate for light and electron microscope studies. Addition of sodium fluoride, silver nitrate, and β-phenyl propionate inhibited the reaction; low concentrations of E600 and eserine sulfate had no effect, and PCMB and phenyl mercuric chloride enhanced enzymatic activity. On the basis of the action of these inhibitors and activators, the enzyme was characterized as a cathepsin. At the light microscope level, the reaction product was found dispersed irregularly as droplets in the gastrodermal lining. At the electron microscope level, the enzyme was localized in V2 vesicles which, after starvation, engulfed mitochondria and formed cytolysomes. Advanced cytolysomes showed a high degree of esterase activity. They may receive additional secretions directly from other V2 vesicles. Residual bodies derived from the cytolysomes migrate to the edge of the gastrodermis where they are presumably expelled into the lumen. No enzymatic activity was found in the superficial digestive vacuoles or in the lumen of the gut. © 1969.