Unpublished results from our laboratory showed that
colchicine increased the incidence of hyperploid mouse metaphase II (MII) oocytes when injected at the same time as human chorionic gonadotrophin (HCG). The objective of the present study was to determine whether the time of administering
colchicine influenced the incidence of
aneuploidy in MII oocytes. CD-1 mice were given pregnant mare's serum (PMS) and 48 hr later, HCG. An
intraperitoneal injection of 0.2 mg/kg
colchicine was given at +4, +2, 0, -2, or -4 hr relative to HCG. Oocytes were collected 17 hr post-HCG and processed, and chromosomes were subsequently C-banded. The percentage of hyperploid oocytes was 0.77, 2.56, 5.71, 7.79, 3.54, and 2.70 for control, +4, +2, 0, -2, or -4 hr pre/post-HCG, respectively. Chi-square analyses of these data demonstrated that
colchicine significantly increases the proportion of
aneuploid oocytes, and that the relative sensitivity of
colchicine-induced
aneuploidy depends upon the time that this
drug is administered relative to HCG.