A Complete 3D Map of the Aging Ovary Reveals That Egg Activation Is Carefully RegulatedThe mammalian ovary may be far more actively managed than scientists once believed. Each ovary contains thousands of oocytes, ranging from tiny dormant cells to larger eggs enclosed within follicles that have already entered the growth phase. This approach revealed that ovarian aging is not simply a matter of every mouse losing eggs at the same predictable rate. The differences were already detectable before puberty, indicating that the foundations of ovarian reserve may be established very early in life, potentially during embryonic development. In humans, where ovarian reserve varies considerably between individuals, the same principle could be important, although much larger studies will be needed to determine whether the pattern exists.