Demonstration of several sporocysts generations as a normal pattern of reproduction of Schistosoma mansoni.

A thorough study of the development of Schistosoma mansoni demonstrates that asexual reproduction within the vector-mollusc does not proceed according to the usually accepted process. Under natural conditions, daughter sporocysts are capable fo stopping production of cercariae and orienting production towards an additional generation of sporocysts, which themselves will be able to evolve in the same manner. This process intervenes without exception provided that the duration of parasitosis exceeds 40 days (at 26 degrees C). It is observed in three different american strains of S. mansoni. We believe that this is the first demonstration of the existence of several sporocysts generations as an habitual mode of reproduction in the life cycle of Digenea.