Schistosoma mansoni: tracer studies in mice

Mice with patent Schistosoma mansoni infections were injected via the tail vein with peroxidase and Thorotrast, and the ingestion of these tracers by the worms was followed over time. Both tracers are found initially in the crypts of the dorsal tegument of the male; however, the disappearance of the peroxidatic activity from the crypts, presumably by digestion of the peroxidase, occurs prior to the disappearance of the Thorotrast. Only Thorotrast appears in the cecal lumen, and the amount is greater in the female than in the male. Little tracer is ever found between the pair in the gynecophoric canal, and no tracer was ever found in the cytoplasm of the worms. These results suggest that while the tegumental and cecal surfaces are cytoarchitecturally identical in both sexes, they may in fact exhibit functional specializations.