Effect of praziquantel on ultrastructure of Schistosoma japonicum cercariae and schistosomula within mouse skin

When Schistosoma japonicum cercariae were exposed to prazipuantel l vg/ml in dechlorinated water for 0.5-2 h. the glycocalyx in the outer surface of tegument decreased markedly or even disappeared. and the matrix of tegument became sparse and indistinct with a decrease in membranous vesicles. Meanwhile. the muscle layer beneath the tegument exhibited swelling or lysis. and the mitochondria distributed in the muscle and parenchymal cells showed swelling and degeneration. After 4 h, an extensive lysis of cercariae tissues which resulted in the formation of numerous vacuoles with varying sizes could be seen. No apparent alteration in the ultrastructure of cercariae exposed to praziquantel in normal saline was observed. The ultrastructural changes of schistosomula within mouse skin in worm tegument. muscle and parenchymal tissues were similar to those mentioned above 0.5-24 h after ig praziquantel 600 mg/kg to mice infected with cercariae for 3 h.