<i>foxl3</i> , a sexual switch in germ cells, initiates two independent molecular pathways for commitment to oogenesis in medaka

Abstract

Significance In teleost fish, unlike mammals, retinoic acid (RA) does not exert a conspicuous feminization effect of germ cells. Instead, in the teleost fish medaka, foxl3 serves as a germ cell-autonomous factor acting at the very beginning of the sexual fate decision. This study shows that foxl3 initiates oogenesis through two genetically independent pathways, meiosis and follicular development. One pathway, involving rec8a , drives female-specific regulation of meiosis. The other, involving fbxo47 , both directs follicular development and suppresses spermatogenesis commitment. The involvement of two evolutionarily conserved factors in oogenesis suggests the existence of an RA-independent pathway that promotes oogenesis, common in vertebrates. In addition, our findings reveal the timing of the establishment of germ cell feminization.