Interaction between growing oocytes and granulosa cells in vitro

Oocyte growth is accompanied by follicular development in mammalian ovaries. Since the discovery of two oocyte‐derived factors, growth differentiation factor 9 (GDF9), and bone morphogenetic protein 15 (BMP15), knowledge of the bidirectional communication between oocytes and granulosa cells for ovarian function and fertility has been accumulated. In addition, the growth culture system of oocytes has been improved, further promoting the studies on the communication between oocytes and granulosa cells in vitro.