Biochemical and cytochemical studies of digestive-absorptive functions of esophagus, cecum, and tequment in Schistosoma mansioni: acid phosphatase and tracer studies.

Acid phosphatase activity was examined, both cytochemically and biochemically, using beta-glycerophosphate (betaGP) and p-nitrophenyl phosphate (NPP) as substrates. The hydrolysis of these substrates differs in pH optimum and sensitivity to some inhibitors. A latent component of the enzyme activity could be demonstrated with betaGP but not with NPP as substrate. These differences suggest the presence of multiple enzymes operative at acid pH in S. mansoni. Cytochemical localization of the sites of hydrolysis of these substrates shows the major activity of the digestive system to be in the posterior portion of the esophagus and in the cecum. The reaction product in the posterior esophagus is found in small dumbbell-shaped vesicles and in the basal infoldings, while in the cecum it occurs on the apical plasmalemma, basal infoldings, and in pleiomorphic vesicles. The electron-dense tracers, ferritin, peroxidase, Thorotrast, and latex beads were all ingested but none was phagocytized. Tracer material was found in some "apparent" vesicles with subsequently were shown by the lanthanum staining technique to be in communication with the extracellular space.