Numerous investigators have studied the reproductive and genetic toxic
ity of caffeine. Caffeine has also been reported to retard meiotic pro
gression and induce aneuploidy in hamster oocytes in vitro, However, t
he ability of caffeine to induce aneuploidy in mammalian oocytes in vi
vo has not been reported. The objective of this study was to test the
hypothesis that chemical-induced perturbations during in vivo oocyte m
eiotic maturation (OM) predispose oocytes to chromosome missegregation
, Caffeine inhibits cAMP phosphodiesterase, which is needed for dephos
phorylating p34(cdc2) kinase and initiating OM, Following superovulati
on, a dose of 150 mg/kg caffeine was administered to Institute of Canc
er Research (ICR) female mice at various times prior to metaphase I(MI
). Ovulated oocytes were collected from the oviducts and processed for
cytogenetic analysis. Statistical analyses of the frequencies of hype
rploid, MI, diploid, premature centromere separation and single chroma
tids revealed nonsignificant (P > 0.05) differences between the contro
ls and each of the caffeine groups. Structural chromosome aberrations
were not found, Under our experimental conditions, we rejected the hyp
othesis and concluded that caffeine neither retarded the rate of OM no
r increased the incidence of aneuploidy in mouse oocytes. The factors
responsible for the different in vivo and in vitro responses require i
nvestigation.