A recent study in Nature Medicine indicates that the human ovary contains rare cells that have the developmental capacity to form immature eggs, called oocytes, in adulthood. The research, by White, Woods, Takai, Ishihara, Seki, and Tilly, suggests that oocyte precursors may exist in the adult human ovary. The current dogma is that cells able to become oocytes are produced prior to birth.
Tilly’s group suggests that a woman’s ovaries contain presumptive stem cells that, when isolated, purified, and cultured in a laboratory, can divide and differentiate into cells that express oocyte-specific genes.
Many questions still remain regarding these rare cells within the adult human ovary. For example, stem cells are undifferentiated cells with the capacity to become specialized cells. However, it is not known if the rare cells described in the study are already immature oocytes. It is also not known where these rare cells may be located within the mature ovary, how many of these cells are in the adult human ovary, or what physiological role, if any, they may play in fertility. Gaining an understanding of these issues would help scientists better understand the cells and their potential.
Our Oncofertility Virtual Grand Rounds speaker, David Albertini, PhD, was quoted in the New York Times stating the new study is, “along a completely different line,” but still should be interpreted with caution until other researchers have been able to repeat it. Dr. Albertini also said that the study's use in fertility treatments would be far off because cells grown in the laboratory often develop abnormalities, a problem that would need correction before any egg could be accepted for fertilization.
Like all rigorous scientific research, we eagerly await the verification of these results and gaining further understanding of how these cells may be useful to young cancer patients who may lose their fertility due to chemotherapy, radiation, or surgery.