Figure 1. Recruitment and growth of oocytes, from PGC stage through mature follicle, illustrating various growth factors mediating development.

Known components of this sequence include granulosa precursors (red), theca compartment (blue), and germ cells (black). Upstream contributions by ovarian stem cells (OSC) may be possible under conditions enabled by growth factors released by platelet-rich plasma (PRP-GFs). Other relevant regulators are BMP2, BMP6, and BMP8β, which are involved in cytokine–cytokine receptor interactions; and Transforming growth factor β (TGF-β), which activates various substrates and regulatory proteins inducing transcription of genes for differentiation, chemotaxis, and proliferation. Later direction is under control of BMP15, a paracrine signal exclusively expressed in ovarian tissue which is involved in oocyte and follicular growth, as well as GDF9, a down-regulator of inhibin-A and promoter of further follicular maturation.