[Regulation of resting follicle activation]

In humans, folliculogenesis starts when some resting follicles leave the ovarian reserve to enter the growing phase. Activation of resting follicles remains poorly understood, however recent data show existence of a balance between activating and repressing factors. Many molecules, comprised KIT ligand, bind a protein kinase receptor and activate the phosphatidylinositol kinase (PI3K) signaling pathway, which contains enzymes and transcription factors that either stimulate or inhibit activation of resting follicles. Some inhibiting (AMH) or activating (activin, BMPs) molecules belong to the TGF-ß super-family, while others can either stimulate (LIF, androgens) or inhibit (estradiol, progesterone, somatostatin) activation of resting follicles. The understanding of molecular mechanisms controlling activation of resting follicles has significant clinical implications in mobilizing resting follicles in patients suffering from infertility due to ovarian dysfunction either spontaneous or resulting from cancer treatments.