Oocyte-Somatic Cell Interactions and Ovulation Rate: Effects on Oocyte Quality and Embryo Yield

Abstract

The use of exogenous gonadotropins to increase oocyte yields for better pregnancy outcomes remains unpredictable and inefficient. The ­objectives of this review are to address two questions concerning this issue: (1) are there any alternatives for improving consistency in oocyte yields? (2) is it possible to develop a molecular diagnostic test for oocytes with blastocyst potential? Studies in sheep with a heterozygous inactivating mutation in the oocyte-derived growth factor, bone morphogenetic protein 15 (BMP15), report increased oocyte yields and significantly more offspring. Moreover, partial immuno-neutralization of BMP15 bioactivity increases oocyte yield without modifying gonadotropin or ovarian steroid secretion. Therefore, it is hypothesized that the development of BMP15 antagonists may prove them to be suitable alternatives to exogenous gonadotropins. Recent evidence from analyses of candidate gene expression in human cumulus cells separated from individual oocytes before IVF indicates a potential non-invasive molecular screen for oocytes with improved blastocyst and live-birth outcomes.