In vitro fertilization and development of ova obtained from female mice treated with aminopterin and mitomycin C.

We examined the effects of mitomycin C and aminopterin on ovulation in vivo and, fertilization, subsequent cleavage and implantation in slc-ICR female mice using methods of fertilization and culture in vitro. Chemicals were injected into mice at the MI (meiosis I) stage or 3 hours before the MI stage in order to examine their toxicity. Mitomycin C did not affect ovulation, but decreased the rate of fertilization. A high dose of mitomycin C (4 mg/kg) inhibited fertilization and the development of ova to the 2-cell stage. Aminopterin affected neither ovulation nor fertilization. At either the MII (meiosis II) stage or 3 hours before the MII stage, high doses (4 and 2 mg/kg) of mitomycin C arrested cleavage and implantation. The cleavage was blocked frequently between the 3-4 cell stage and the 5-8 cell stage. Aminopterin affected neither cleavage nor implantation.