The genetic make-up of ovarian development and function: the focus on the transcription factor FOXL2

In a 46 XY individual, the presence of the Y chromosome harboring the testis-determining factor (SRY) triggers testis determination and differentiation. In a 46 XX individual, the absence of SRY and the activation of genes associated with the female pathway lead to ovarian development. The latter process has long been considered as a default pathway. However, recent studies have cast doubts on this dogma. Here, after a brief overview of the main steps of ovarian development, we focus on three genes WNT4, RSPO1 and FOXL2 that are essential for ovarian determination, differentiation and/or maintenance. Special attention is paid to FOXL2 whose mutations are responsible for the blepharophimosis syndrome, often associated with female infertility, and for cancer. We highlight the cooperation of WNT4, RSPO1 and FOXL2 within a regulatory network and the need for further research to better understand their role in defining and maintaining ovarian identity.