本实验以约氏疟原虫一斯氏按蚊系统,研究了乙胺嘧啶对疟原虫卵囊发育的影响。受染斯氏按蚊叮咬喂药鼠或直接饲以含药糖水后,蚊胃卵囊感染率及感染度均低,卵囊个体小,每日平均增长率亦低。电镜和Feulgen染色观察表明:用药组卵囊胞浆空泡化、色素堆积,形成黑孢子,卵囊DNA平均含量明显低于对照组。卵囊发育中未出现细胞核及成孢子细胞,提示乙胺嘧啶有抑制疟原虫卵囊DNA合成的作用。 In this experiment, Plasmodium yoelii-Anopheles stephensi system was used to study the effect of pyrimethamine on the development of malaria oocysts. Anopheles sinensis infected bite feeding rats or directly fed with medicated syrup, the mosquito stomach oocyst infection rate and the infection are low, small individual oocysts, the average daily growth rate is also low. Electron microscopy and Feulgen staining showed that the cytoplasm of oocysts in the drug-treated group were vacuolized and pigment accumulated, forming black spore. The average content of oocyst DNA was significantly lower than that of the control group. No oocysts and sporozoites were observed in the development of oocysts, suggesting that pyrimethamine could inhibit the DNA synthesis of the malaria parasite oocysts.