AIM: In order to understand the pharmacological effect of artemether on the ultrastructure of schistosomes. METHODS: On d 7 or d 35 after infection with Schistosoma japonicum cercariae, mice were treated intragastrically with artemether at a daily dose of 200 mg·kg -1 for 2 d. On d 1, 3, 7, 14 and 28 after treatment, the animals were sacrificed and the worms were collected for transmission electron microscopic (TEM) study. RESULTS: One to 7 d after treatment, ultrastructural damage by artemether were apparent in the tegument, syncytium, musculature, parenchymal tissues, intestinal epithelial cells and vitelline cells. The major changes in the tegument involved loss of definition, sparseness, vacuolation and lysis in the matrix; loss of definition, fusion, increase in electron density and disruption of the outer plasmic membrane of the tegumental cytoplasmic processes and degeneration of sensory structures. In the subtegumental muscles, syncytium, parenchyma tissues and intestinal epithelial cells, extensive swelling, lysis and vacuolation were usually seen. The vitelline cells of female worms were similarly affected, including vacuolation of nucleoli, decrease in granular endoplasmic reticulum, and lysis of vitelline balls. Fourteen to 28 days after treatment, ultrastructural damage from artemether was recovered in some survived worms while in others irreversible damage remained. CONCLUSION: Artemether apparently damaged both 7 d old schistosomules and 35 d old adult worms.
