Egg cells survive nearly a year in a dormant state in mice
Egg cells can remain active far longer than previously thought, by drastically slowing their metabolism. Researchers found this in mice, with potential implications for understanding female fertility and reproductive aging.
Women are born with a fixed supply of egg cells. That supply decreases throughout life, and when most eggs are gone, menopause begins. But how long an egg cell can actively ‘wait’ before being used or lost was not well understood. A piece published in Nature Aging describes how the study by Liang and colleagues shows that activated egg cells in mice can persist within ovarian secondary follicles for nearly a year, by sharply reducing protein production and metabolic activity.
Slowed biology as a survival strategy
A follicle is the small sac in the ovary that surrounds and protects an egg cell. When a follicle is ‘activated’, the egg cell typically begins to mature. What the researchers found is that activated egg cells can remain in a state of reduced biological activity rather than immediately maturing or being lost. This appears to be a way in which the ovarian reserve is preserved for longer.
What this means for fertility and aging
According to the authors, better understanding of this mechanism may offer insight into how and when follicles are lost in women, which is directly relevant to the pace of reproductive aging. The research was conducted in mice; whether the same mechanism operates in humans is not addressed in the source text. The article is a News & Views commentary accompanying a separate study by Liang et al. published in the same journal.
Search terms to explore further: ovarian follicle activation, reproductive aging ovary, oocyte metabolic dormancy