VARIATION OF MOUSE OOCYTE SENSITIVITY TO GRISEOFULVIN-INDUCED ANEUPLOIDY DURING THE 2ND MEIOTIC DIVISION

The effects of griseofulvin (GF) treatment during the second meiotic d ivision of oogenesis were investigated by cytogenetic analysis of mous e one-cell (1-Cl) zygotes, After determining the duration of fertiliza tion and the second meiotic division, 1500 mg/kg GF were administered to superovulated mice at 10, 12 or 14 h after human chorionic gonadotr ophin (HCG) injection, The results showed that GF reduced the frequenc ies 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 hyp erdiploidy, The maximum frequency of hyperdiploidy (39.6%) occurred wh en GF was given 10 h after HCG, Polyploid 1-Cl zygotes were significan tly induced only at the 10 and 12 h treatment times and their level ne ver exceeded 1.8% of fertilized oocytes. GF also induced abnormalities of chromosome condensation along with centromeric chromosome associat ions, These results support the conclusion that GF treatment during th e second meiotic division induced aneuploidy, polyploidy, and reduced rates of fertilization and zygotic development. Also, the time of chem ical treatment influenced the frequencies of these effects.