In vitro activation of dormant follicles for fertility preservation

Recent advances in radiotherapy and chemotherapy have led to higher cure rates for female children and adolescents with cancer. However, these treatments adversely affect germ cell survival, and ovarian failure is thus a probable side effect of these anticancer therapies. Moreover, an increasing number of women are choosing to postpone childbearing until later in life, but their primordial follicle reserves degenerate with advancing age. Thus there is a pressing need for the development of fertility preservation methods for these individuals. Ovarian tissue cryopreservation prior to loss of the primordial follicle population either due to cancer treatments or normal aging is a promising option for safeguarding fertility. A complete in vitro maturation (IVM) system could help generate mature eggs for later use without the patient having to undergo the cumbersome process involved in current assisted reproduction methods to generate mature eggs. Cryopreserved ovarian cortical tissues have attracted the attention of reproductive biologists and clinicians because of the large number of safely frozen primordial follicles in them, and it is theoretically possible to use these follicles for in vitro activation (IVA) and subsequent IVM. Ovarian tissue collection is independent of patient age and social or personal conditions. Despite being widely accepted potential techniques for fertility preservation, IVA and IVM of human primordial follicles to obtain fertilizable eggs remains far from reality. This chapter highlights the current achievements and obstacles in obtaining growing follicles through activation of dormant follicles.