BMP15, or GDF9B is a member of the bone morphogenetic protein family which is part of the transforming growth factor-beta superfamily that are involved in embryonic development and adult tissue homeostasis. BMP15 is expressed exclusively in the oocyte. It is an oocyte-specific growth/differentiation factor that may be involved in oocyte maturation and follicular development (1-3). Defects in BMP15 are the cause of ovarian dysgenesis type 2. BMP15 could be used as an oogenesis marker to track human amniotic fluid stem cells differentiation into the oocyte-like cells.