RESUMO
The aim of this research was to study the effects of different doses of LIF on GVBD and MII development rate and cumulus expansion. Immature mice superovulated with HMG and GV oocytes obtained from ovary 48 hours later. The GV oocytes were cultured in TCM199 with 100, 500 and 1000 RI /ml LIF. Cumulus expansions were evaluated with two examiners and numbers of MII oocytes were recorded. For denuding the oocytes hyaloronidase was used. Our results showed that the rate of GVBD and MII development increased in -groups with LIF compared with control group. Rate of MII development with 1000 IU/ml LIF was significantly higher than that of control group [P<0.05]. Cumulus expansion in group with 1000 IU/ml LIF improved significantly compared with control group [p<0.05]. Our results showed that LIF could improve IVM rate in dose dependant. Also cumulus expansion improved in group with LIF and increased oocyte quality