Figure 11.

Hedgehog regulation of ovarian steroidogenesis. Granulosa cells (GCs) in activated ovarian follicles express DHH and IHH. The HH molecules secreted from the GCs bind the PTCH receptors expressed on theca cell (TC) precursors to induce their differentiation. Development and differentiation of TCs are essential for steroidogenesis and follicle maturation beyond early antral stage. While GDF9 expressed by oocytes act on GCs to induce DHH and IHH expression, the HH molecules are essential for TC functions. Thus, HH signaling establishes a signaling link among the germ cells and somatic cells of ovarian follicles.