Germinal Vesicle Transfer between Young and Aged Mouse Immature Oocytes

Abstract: To elucidate effects of nucleus or cytoplasm from different age of animals on oocyte maturation， Ca²⁺ oscillations and karyotypic status， germinal vesicles were exchanged between immature oocytes from mice of 6-8 weeks (6W)， 9 months (9M) and 12 months (12M). Five groups of reconstructed oocytes were obtained by micromanipulation and electrofusion. Oocytes in five experiment groups and three control groups showed a similar pattern of Ca²⁺ oscillations by Sr²⁺ induction. The rates of the matured oocytes with premature chromatid separation for group 6W GV-6W cytoplast， group 6W GV-9M cytoplast and group 6W GV-12M cytoplast were comparable to those of control 6? weeks (P>0.05)， but significantly lower than those of control 12 months (P<0.01). However， the rates of the matured oocytes with premature chromatid separation increased for group 9M GV-6W cytoplast and group 12M GV-6W cytoplast. These findings demonstrate that oocytes reconstructed by GV exchange between young and aged mice show normal maturation and Ca²⁺ oscillation. It seems that the aged-related meiotic anomalies may be due to nucleus or chromosomes rather than cytoplasm.

CSTR: 32200.14.cjcb.2007.02.0013