Updated project metadata. Foxl2 is a forkhead transcription factor essential for proper reproductive function in females. It is expressed in the somatic cell population of the gonad (granulosa cells) which forms the follicles of the ovary, the structures responsible for embedding and nurturing the oocytes during their development. FOXL2 directly regulate the aromatase that synthesizes estrogens CYP19A1, thus promoting female differentiation, as well as acting as a repressor of the male factors SOX9 and DMRT1.Expression is also found in the eyelids, pituitary gland and uterus. In the goat, frog and many fish species FOXL2 is a sex-determining gene which, when deleted, leads to female-to-male sex reversal.