Origin of Germ Cells and Follicular Renewal in Adult Human Ovaries

The origin of oocytes and primary follicles in ovaries of adult mammalian females has been a matter of dispute over one hundred years and resulted in the dogma that all oocytes in adult mammalian females persist from the fetal period of life. However, from a phylogenetic viewpoint, it seems contradictory that mammalian females, including humans, would evolve a uniquely retrogressive reproductive mechanism, whereby they are required to preserve their gametes from the fetal period for up to several decades. Mitotically active germ cells have been reported in ovaries of adult prosimian primates [1] and mice [2], and we have shown that mesenchymal cells in ovarian tunica albuginea differentiate into surface epithelium, a source of germ cells entering vessels and contributing to the follicular renewal in adult human females These reports represent challenges to the established dogma on fetal origin of mammalian eggs