BMP15 (bone morphogenetic protein 15) is an oocyte-secreted factor exclusively expressed in oocytes that plays a critical role in ovarian folliculogenesis and female fertility 1. As a member of the transforming growth factor beta superfamily, BMP15 modulates granulosa cell fate and oocyte developmental competence through paracrine signaling 2. The protein stimulates follicle growth and cumulus cell expansion, with particular importance in the oocyte-cumulus cell dialog that determines oocyte meiotic competence 3. BMP15 mutations cause primary ovarian insufficiency (POI) through impaired oogenesis and activation of macrophage-mediated ovarian failure pathways 4. Genetic studies confirm BMP15 as a major gene causing POI, with heterozygous mutations increasing ovulation rate in sheep while homozygous mutations cause infertility 1. In humans, BMP15 mutations account for a subset of genetic POI cases and are among the few single genes with unequivocal deleterious effects across populations 5. Additionally, BMP15 expression is downregulated in polycystic ovary syndrome, where androgen excess impairs follicular development 6. The therapeutic potential of BMP15 modulation remains an important avenue for treating female infertility and ovarian dysfunction.