Background: Successful oocyte in vitro maturation (IVM) would eliminate the need for hormonal stimulation used in assisted reproduction techniques. Unfortunately, oocytes matured in vitro have compromised developmental competence possibly due to disrupted oocyte-cumulus communication resulting from inappropriate levels of oocyte-secreted factors such as growth differentiation factor 9 (GDF9). Hence, the aim of this study was to investigate the effects of exogenous GDF9 during IVM of mouse oocytes on development and subsequent fetal viability.
Methods: Cumulus-oocyte complexes from pregnant mare's serum gonadotrophin primed mice were cultured with or without 200 ng/ml exogenous recombinant GDF9, 50 mIU/ml FSH and 10 ng/ml epidermal growth factor (EGF). After 18 h, cumulus expansion was scored and oocytes were fertilized in vitro. Cleavage, blastocyst development, blastocyst total, inner cell mass (ICM) and trophectoderm cell numbers were assessed. Viability of embryos was assessed by transfer to recipient females and pregnancy outcome determined at day 15.
Results: Oocytes matured with exogenous GDF9 in the presence of FSH and EGF had higher rates of development, percentage of hatching blastocyst and blastocyst total and ICM cell numbers (all P < 0.05). Although implantation rate and fetal and placental weights were not affected, the number of viable fetuses at day 15 was increased with exogenous GDF9.
Conclusions: Exogenous GDF9 during IVM improved embryo development and fetal viability and provides a promising approach for human IVM.