Schistosoma mansoni: in vitro conversion of cercariae to schistosomula.

Schistosoma mansoni cercariae were incubated for 3-5h at 37 degrees C in various test solutions, and the rate and extent of conversion of the cercariae to schistosomula were determined. Criteria used to identify schistosomula included: (1) loss of cercarial tail, (2) viability of organisms in saline but not in water, (3) pre-acetabular gland evacuation and (4) ability to survive in culture. Incubation of cercariae in rat chamber fluid resulted in organisms which were water sensitive, but retained their tails and pre-acetabular gland contents. Conversion to water sensitivity was not blocked by 0-01 M EDTA.