Fig. 3.

GDF9, BMP15 and KITL interactions during oocyte and follicular development. In rodents, KIT activation, primarily by KITL2, promotes oocyte growth and survival. Both GDF9 and BMP15 promote proliferation of granulosa cells from small antral follicles and BMP15 inhibits FSH-stimulated progesterone production and luteinization. GDF9 suppresses granulosa cell expression of both Kitl1 and Kitl2, whereas BMP15 stimulates Kitl expression in granulosa cells in both rats and mice. In turn, KITL inhibits Bmp15 expression in oocytes via KIT signalling.