Variation of mouse oocyte sensitivity to griseofulvin-induced aneuploidy during the second meiotic division.

The effects of griseofulvin (GF) treatment during the second meiotic division of oogenesis were investigated by cytogenetic analysis of mouse one-cell (1-Cl) zygotes. After determining the duration of fertilization and the second meiotic division, 1500 mg/kg GF were administered to superovulated mice at 10, 12 or 14 h after human chorionic gonadotrophin (HCG) injection. The results showed that GF reduced the frequencies of fertilized oocytes (P < 0.01) and of 1-Cl zygotes that reached the first mitotic metaphase stage (P < 0.001). Aneuploidy was induced regardless of the moment of treatment, but the various treatment times were associated with statistically different (P < 0.05) levels of hyperdiploidy. The maximum frequency of hyperdiploidy (39.6%) occurred when GF was given 10 h after HCG. Polyploid 1-Cl zygotes were significantly induced only at the 10 and 12 h treatment times and their level never exceeded 1.8% of fertilized oocytes. GF also induced abnormalities of chromosome condensation along with centromeric chromosome associations. These results support the conclusion that GF treatment during the second meiotic division induced aneuploidy, polyploidy, and reduced rates of fertilization and zygotic development. Also, the time of chemical treatment influenced the frequencies of these effects.