Jb. Mailhes et F. Marchetti, THE INFLUENCE OF POSTOVULATORY AGING ON THE RETARDATION OF MOUSE OOCYTE MATURATION AND CHROMOSOME SEGREGATION INDUCED BY VINBLASTINE, Mutagenesis, 9(6), 1994, pp. 541-545
Certain compounds can induce ovulated metaphase I (MI) oocytes. To stu
dy if these MI oocytes can overcome this blockage, ICR mice were given
human chorionic gonadotrophin and 0.6 mg/kg vinblastine sulfate (VBS)
. Their ovulated oocytes were collected at 17, 19, 21, 23 and 25 h lat
er. The results showed that the frequencies of MI oocytes decreased, t
he proportions of diploid metaphase II (MII) oocytes increased and the
frequencies of hyperploid MII oocytes did not significantly differ (P
> 0.05) among the five harvest or postovulatory times. We also found
that the proportions of MII oocytes exhibiting premature anaphase II a
nd premature centromere separation increased with postovulatory ageing
, and that these frequencies were consistently higher in controls than
in the VBS groups. These findings indicate that some of the oocytes b
locked in MI can overcome this inhibition and produce primarily diploi
d MII. oocytes. The ultimate fate of ovulated MI and diploid oocytes o
n aneuploid production hinges upon the formation of a functioning meio
tic spindle, which is affected by both dosage and the specific chemica
l.