Here’s how it could go: Some day in the future, it’s routine for every young woman of a certain age—for argument’s sake, let’s say 21—to undergo a procedure to snip off a piece of tissue from one of her ovaries. Her doctor slices up the tissue into a half-dozen or so microthin sections; these are frozen, to be used whenever she’s ready for a baby. Her ovaries function normally, and she keeps menstruating and ovulating just as she has since puberty. But she doesn’t worry about rushing into baby-making. The timetable of how her life unfolds need not adhere to a pesky biological clock.
Later, maybe much later, maybe not for another 20 years, this woman wants to start a family. She remembers those strips of ovarian tissue in deep freeze. Each strip contains thousands of follicles, the proto-eggs of the ovary, preserved at their peak. The follicles in her body have been getting progressively less robust, but in the lab freezer her proto-eggs have been in suspended animation, protected from the degradation of age.
So she goes back to the doctor, who defrosts one of the strips and implants it in her ovary. It becomes established there, starts pumping out hormones at the level of a younger woman, and transforms one follicle each month into a mature egg. Each menstrual cycle, the hardy egg of a 21-year-old is deposited into the fallopian tube, where it can be fertilized. Ideally, one of those youthful eggs turns into an embryo that embeds itself in the uterus and grows into a healthy baby. Ideally, that one strip of ovarian tissue keeps producing hormones and releasing eggs for years, long enough for the woman—who might be 45 or even older by the time it’s all done—to have a couple of children.
If the first implant doesn’t work, or if it stops working before the woman’s family is complete, doctors can defrost and implant another strip. And if she doesn’t need the strips for childbearing—maybe she decides not to have children at all, or she gets pregnant naturally without needing to take any strips out of deep freeze—she can use them for a different purpose: postponing menopause. As she enters her fifties, this woman thaws a strip and has it implanted in her forearm, where it releases estrogen and other sex hormones in a way that mimics the feedback loop of a younger woman, in theory with fewer side effects than with artificial hormones. She still menstruates, which is the downside, but she also remains at lower risk of chronic conditions, like heart disease and osteoporosis, that usually get worse after menopause, at least in part because of the drop in estrogen. In this future, the one-two punch of nature’s timetable—first making it harder to have healthy babies after about age 35, then making it harder to stay healthy yourself after about age 50—is something women have finally transcended.
Here’s the reality of where things stand: At the Center for Human Reproduction in New York, there’s a room with a boxy machine that slow-freezes slices of ovarian tissue before they are transferred to a stubby deep-freeze tank that bears an uncanny resemblance to R2-D2. But of the 14 tanks in the room, most contain frozen embryos or frozen eggs or sperm, not ovarian tissue. That’s because right now, removing ovarian tissue involves an expensive surgery requiring a hospital stay. (Infertile men can have a bit of testicular tissue removed via a comparatively simple probe-and-snip procedure; the hope is that a similar procedure can be developed for women.) Transplanting the tissue later requires another operation.