Setting the record straight on data supporting postnatal oogenesis in female mammals.

Of all the 'certainties' in mammalian female reproductive biology, the concept that a non-renewing oocyte reserve is set forth in the ovaries at birth may be the most longstanding and widely held. However, when data from our studies of oocyte apoptosis unintentionally began to contradict this theory in the latter part of 2002, we embarked on an investigation, unbiased by any pre-conceived dogmas, to determine if oocyte production persists in adult female mice. In 2004, we presented our first experimental findings in the journal Nature, which indicated that oogenesis indeed continues in adulthood. Amidst widespread skepticism, we moved forward with our studies and this year published our follow-up experiments in the journal Cell. Results from this latter body of work not only reinforced our earlier conclusions but also identified bone marrow as a surprising source of oocyte-producing germ cells in adults. Although this study has also been met with skepticism, doubts raised in commentaries on our work are largely based on inaccurate or incomplete assessments of our experimental models and results. Here we have attempted to clarify published misperceptions and misinterpretations of our data, and offer additional insights that challenge the idea of fixed endowment of oocytes at birth.