Figure 1. Ovarian steroidogenesis. (A) Normal ovarian steroid synthesis. (B) PCOS ovarian steroid synthesis. In comparison to normal theca cells, PCOS theca cells show increased expression of LH receptor and increased expression of CYP17A1 gene, leading to enhance of 17α-hydroxylase and 17,20-lyase activity, and amplifying androgen synthesis. Exogenous factors, such as hyperinsulinemia and IGFs are modulatory hormones that can disrupt normal intra-ovarian regulatation of steroidogenesis.
