Abstract: It is reported in this paper that the mice infected with P.y.y. game-tocytes were administe red for a dose of MP0090 5mg and 10mg/kg respe-ctively, 2 hours later, they were blood-mealed by Anopheles stephensi. We dissected the mosquito’s midguts on the 7th, 9th and 11th day, and observed them under TME. It was seen that the number of oocysts affected by the two doses decreased evidently. The growth of oocysts was rest-rained. As a result, there were numerous vacuoles in the oocyst, and the normal structure almost disappeared. The sporozoites also presented vacuoles markedly. The results showed that the drug MP0090 can inhibit sporogony indirectly, and the inhibition can become stronger with the increase of the concentration of the drug.

Key words: 5-p-fluoro-phenoxyl-prima quire citrate, gametocyte, sporogony, Plasmodium yoelii yoelii-Anopheles stephensi system, indirect inhibition