Objective:To establish a culture model for studying the interaction between oocytes and cumulus cells in the strain of ICR mice that are frequently used in biomedical research in China,and using this model to study the effect of oocytes and oocyte-derived paracrine factors growth differentiation factor 9(GDF9) and bone morphogenetic protein 15(BMP15) on cumulus expansion,which is one of the key ovulatory processes. Methods:Oocytectomized cumulus complexes (OOX)were constructed by microsurgical removal of the oocyte from the cumulus-oocyte complexes,and the effect of oocyte and paracrine factors on EGF-induced cumulus expansion was studied by co-culturing the OOX with oocytes and treating the OOX with recombinant GDF9 and BMP15. Results:The model of OOX culture was successfully established using ICR mice,and the oocyte and its paracrine factor GDF9 and BMP15 were found to be essential for EGF to induce cumulus expansion. Conclusion:Oocytes promote key ovulatory processes in ICR mice.