The impact of vitrification on murine germinal vesicle oocyte In vitro maturation and aurora kinase A protein expression.

PURPOSE

Investigate the effect of vitrification on in vitro maturation (IVM) and expression of Aurora kinases A, B, and C in germinal vesicle (GV)-stage oocytes.

METHODS

GV-stage oocytes from B6D2F1 female mice 7-11 weeks of age were vitrified after collection, thawed, and matured in vitro for 0, 4, 8, and 12 h (hrs). The rate of germinal vesicle breakdown (GVBD), spindle apparatus assembly, and Aurora kinase mRNA and protein expression during IVM was measured.

RESULTS

Oocyte vitrification was associated with significant delays in both GVBD and normal spindle apparatus assembly at 4 and 8 h of IVM (p < 0.05). There was no difference in mRNA levels between control and vitrified oocytes for any of the Aurora kinases. Aurora A protein levels were reduced in vitrified compared to control oocytes at 0 h (p = 0.008), and there was no difference at 4 and 8 h (p = 0.08 and 0.69, respectively) of IVM.

CONCLUSIONS

Vitrified oocytes have delayed GVBD and normal spindle assembly during in vitro maturation. Reduced levels of Aurora A protein immediately post-thaw may be associated with the impaired oocyte maturation manifested by the delayed progression through meiosis I and II, and the atypical timing of the formation of meiotic spindles in vitrified GV-stage oocytes.