effects of cumulus cells on in vitro maturation of mouse germinal vesicle stage oocytes

ABSTRACT

In vitro maturation [IVM] of oocytes is a promising technique to reduce the costs and avert the side-effects of gonadotropin stimulation for in vitro fertilization [IVF]. The pregnancy rates from oocytes matured in vitro are much lower than those of in vivo stimulation cycles, indicating that optimization of IVM remains a challenge. In this study, we investigated the effect of cumulus cells on maturation and fertilization rate of immature oocytes [Germinal vesicle]. Germinal vesicle [GV] oocytes were recovered from 6-8 weeks old Balb C female mice 48hr after injection of 10 IU pregnant mare serum gonadotropin [PMSG]. Collected oocytes were divided into two groups. Group A GV oocytes without cumulus [denuded oocyte]. Group B GV oocytes with cumulus cells [cumulus-oocyte complex]. The oocytes in both groups were cultured in TCM-199 medium in a humidified atmosphere of 5% CO2 in air at 37?C. The maturation, fertilization and developmental rates were recorded after 24hr. Maturation, fertilization and developmental rates in denuded oocytes [DO] were 65.1%, 68.02%, 78.63% respectively, and in cumulus-oocyte complex [COC] were 78.20%, 85.57% and 85.05%, respectively. The maturation, fertilization and developmental rates of COC were significantly higher than those of DO [p<0.05]. The results show that cumulus cells have beneficial effects on maturation, fertilization and cleavage rates of mice oocytes