Comparative gene expression profiling of adult mouse ovary-derived oogonial stem cells supports a distinct cellular identity

Freshly isolated OSCs exhibit a germline gene expression profile that overlaps with, but is distinct from, that of PGCs and SSCs. After in vitro expansion, OSCs activate expression of pluripotency genes found in freshly isolated PGCs. In vivo, OSC numbers in the ovaries fluctuate during the estrous cycle, with the highest numbers noted during the luteal phase. This is followed by activation of Stra8 expression during the follicular phase, which may signify a wave of neo-oogenesis to partially offset follicular loss through atresia and ovulation in the prior cycle.