 The close proximity between the cumulus oophorus cells and the oocyte favors bidirectional communication, which is vital for oocyte development.As a part of the process of in vitro fertilization, gene expression profiling of cumulus cells can be performed to estimate oocyte quality and the efficiency of an ovarian hyperstimulation protocol, and may indirectly predict oocyte aneuploidy, embryo development and pregnancy outcomes.Increased knowledge in these aspects is useful in, for example, embryo selection.