Ultrastructural observations on damage to schistosomula of Schistosoma japonicum by mouse neutrophils in vitro.

Ultrastructure of schistosomula of Schistosoma japonicum was studied in relation to the effect of mouse neutrophils in vitro. In the presence of antibody and complement, damage to the schistosomular tegument covered with many neutrophils began to appear within 1 h incubation. Exfoliation of the granular cytoplasm of the tegument, disorganization of the muscle layers and vacuolation in the inner tissues were seen in a part of neutrophil-attached parasites by 2 h incubation. However, the majority of schistosomula with fewer cells retained their integrity till 16 h. The cytochemical examination of schistosomula incubated with mouse neutrophils for 1 and 2 h demonstrated clearly the localization of the peroxidase activity on the surfaces of the cells and the parasites.