Current mechanisms of primordial follicle activation and new strategies for fertility preservation.

Premature ovarian insufficiency (POI) is characterized by symptoms caused by ovarian dysfunction in patients aged <40 years. It is associated with a shortened reproductive lifespan. The only effective treatment for patients who are eager to become pregnant is IVF/Embryo Transfer (ET) using oocytes donated by young women. However, the use of the technique is constrained by the limited supply of oocytes and ethical issues. Some patients with POI still have some residual follicles in the ovarian cortex, which are not regulated by gonadotropin. These follicles are dormant. Therefore, activating dormant primordial follicles (PFs) to obtain high-quality oocytes for assisted reproductive technology may bring new hope for patients with POI. Therefore, this study aimed to explore the factors related to PF activation, such as the intercellular signaling network, the internal microenvironment of the ovary and the environment of the organism. In addition, we discussed new strategies for fertility preservation, such as in vitro activation and stem cell transplantation.