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Abstract: The purpose of this review is to present the strategies for fertility preservation that are currently proposed to patients at risk from premature ovarian failure (POF) due to chemotherapy as well as some future solutions that could allow patients already affected by an IOP to recover their fertility. Today, cryo-preservation of pieces of ovarian cortex followed by orthotopic transplantation as well as in vitro maturation of oocytes (IVM) allow preservation of fertility in patients being to undergo an antitumor treatment. However, although promising results have been obtained, the pregnancy rate remains very low. Improvement of these techniques, but also stimulation of resting follicle activation, in vitro folliculogenesis, and culture of putative oogonia that may be present in the adult ovary, are all future opportunities for patients suffering from an IOP, and are currently the subject of intensive researches. [Copyright &y& Elsevier]

Abstract: It is a central dogma of female reproductive biology that oogenesis ceases around the time of birth in mammalian species. In 2004 and 2005, two studies were published by Johnson et al., in which they claimed that in the adult mouse ovary, neo-oogenesis takes place and originates from female germline stem cells that are present in either the ovarian surface epithelium or bone marrow. Following these publications, experiments showed that non-germinal stem cells could generate oocytes. However, in the mouse, ability of extra-ovarian stem cells to refurbish the ovary in new oocytes competent to ovulate, and subsequent existence of a spontaneous neo-oogenesis in the adult ovary in normal physiologic conditions, have been disputed. Morphologic studies performed in the adult mouse ovary showed that atresia of the immature follicle pool was strongly overestimated by Johnson et al., and that no intermediary stages of meiosis were seen. These observations led to the conclusion that adult female mice do not need neo-oogenesis for maintaining a normal reproductive function. However, a recent study have shown that female germline stem cells might be present in the ovarian surface epithelium in mice and humans. When sampled in GFP transgenic mice, cultured for a long period and transplanted into ovaries of sterilized mice, these cells underwent oogenesis and the mice produced offsprings. These new data support the possibility to experimentally restore fertility in women suffering from a premature ovarian failure. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Fertility preservation (FP) techniques are progressing rapidly these past few years thanks to the oocyte vitrification. Indication of FP techniques is now extended to non-oncological situation that may induce risk of premature ovarian failure. Ovarian endometriosis can lead to premature ovarian failure and further infertility due to the high risk of ovarian cysts recurrence and surgery. To date, there is no cohort study regarding FP and endometriosis as well as no recommendation. Our purpose is to review the arguments in favor of FP in this specific area and to elaborate strategies according to each clinical form., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)