[Mutagenic action resulting from the preovulatory administration of chloridine on preimplantation rat embryos].

Pyrimethanine (2 and 5 mg/kg) injected to the adult female rats just before ovulation causes significant dose-dependent reduction in embryo cleavage rate. Pyrimethamine administered in a dose of 2 mg/kg before ovulation has no mutagenic effect on 5-day rat embryos, while 5 mg/kg induced chromosomal aberrations in 14.3% of all 5-day embryos as compared to only 6.3 % embryos with chromosomal aberrations in the control animals. The most common types of chrmosomal aberrations induced by pyrimethamine are trisomy and chromosomal mosaicism.