May be involved in follicular development. Oocyte-specific growth/differentiation factor that stimulates folliculogenesis and granulosa cell (GC) growth. Homodimer. But, in contrast to other members of this family, cannot be disulfide-linked. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The mature protein migrates in two distinct mature proteins, P16 (16KDa) and P17 (17KDa). Ovarian physiology and fertility are controlled by endocrine and paracrine signals. These act in a species-dependent manner and determine the ovulation quota in different mammalian species. While humans, and mammals such as the cow or red deer, normally ovulate only one egg per cycle, other mammals such as mouse and pig can ovulate in excess of ten per cycle. The mechanisms that regulate the species-specific differences in the number of follicles that go onto ovulate during each reproductive cycle are poorly understood. According to PubMed:21970812, mRNA expression levels of GDF9 and BMP15 are tightly coregulated within each species and influence species-specific ovulation-rates. Belongs to the TGF-beta family.