With major knowledge gaps in our understanding of common women’s health issues like polycystic ovary syndrome (PCOS) and endometriosis, and the ubiquitous use of hormonal birth control as a one-size-fits-all Band-Aid for whatever ails you, it should come as no surprise that the female reproductive system has been historically under-researched. The ovaries, two small egg-shaped organs on either side of the uterus, are where the magic (of ovulation) happens. And yet, we know very little about how and why the ovaries do what they do. Researchers are increasingly taking action to rectify these knowledge gaps in our understanding of the female body. One positive step is a recently developed cellular atlas of the human ovary. What scientists learned in the process of mapping the ovary could transform women’s health care via the creation of artificial ovaries.
What does the ovary do?
When a girl is born, her ovaries contain all the immature eggs (roughly 700,000) she will ever have. Most of her follicles, or “egg containers,” are located in the outer layer of the ovary and will never go on to maturation, but will naturally die off as she ages.
By the time a girl reaches puberty, she’ll be “down” to around 400,000 eggs. Starting with her first ovulation (i.e., the release of an egg from a follicle) and continuing for the rest of her reproductive life (with the exception of pregnancy, breastfeeding, or hormonal birth control use), hormones produced by the pituitary gland in the brain and in the ovaries should prompt the maturation of (usually) one follicle per cycle. Once the follicle matures, the egg is released into a fallopian tube, where it awaits fertilization. Throughout the process of egg maturation, the hormone estrogen is produced and released by the ovary.
After ovulation, the empty follicle turns into the corpus luteum, which is responsible for progesterone and some estrogen production throughout the remainder of the menstrual cycle (or for the first trimester, if the woman conceives).
How does the ovary affect reproductive issues like PCOS?
The two ovarian hormones, progesterone and estrogen, affect all of a woman’s reproductive organs and her overall health. Consequently, hormonal disorders necessarily affect ovarian function. PCOS is one of the most common female hormonal disorders, affecting approximately 5% to 10% of women. It is characterized by multiple cysts in the ovaries, often affecting fertility and hormonal well-being in women. Premenstrual syndrome (PMS), another common menstrual disorder, is caused by imbalanced ovarian hormones. Even endometriosis symptoms are affected by the fluctuations of ovarian hormones.
How did scientists create a ‘map’ or ‘atlas’ of the ovary?
In 2024, scientists from the University of Michigan mapped the genetic activity for healthy egg development by making an “atlas” of the cells in the female ovary. Using ovarian tissue provided by five deceased organ donors who were of reproductive age, the researchers analyzed RNA sequences to map the genetic activity pattern needed to develop healthy follicles–that is, follicles which release the correct level of hormones and produce healthy, mature eggs (all of which eventually leads to healthy pregnancies!).
What could this ovary map lead to?
The ovary atlas is far more than just an educational “map” to the ovaries. This research may one day help scientists create the first artificial ovary with functioning follicles. Artificial ovaries could help women who have previously lost their ovaries or ovarian function—from ovarian or other reproductive cancers, premature ovarian failure, PCOS, or other diseases or hormonal disorders—revive hormonal function and potentially reproduce. And, since the Michigan scientists focused primarily on follicular development in the ovary, they now have a greater understanding of the kind of egg development which leads to healthy pregnancies.
Currently, the only option for women who have lost ovarian function is to reimplant previously frozen ovarian tissue, or to extract and freeze their eggs prior to treatment (neither of which guarantees a healthy future pregnancy). Freezing ovarian tissue has a very low success rate for follicle survival, and thus for the restoration of reproductive function. The Michigan researchers believe that artificial ovaries could still come from a woman’s frozen ovarian tissue, taken before treatment or surgery. They hypothesize that they could utilize their new knowledge of ovarian genetic activity to modify the follicles in the artificial ovary to have a higher survival rate, hopefully allowing the woman to conceive a biological child.
What further research is needed?
More research is needed to fulfill the ultimate goal of creating artificial ovaries, but now that there is a greater understanding of healthy follicle and egg development, there’s more hope than ever before for women suffering from a range of ovarian issues.
And scientists do not plan to stop with the ovary. Using the ovary atlas as a guide, they hope to map the other organs of the female reproductive system, particularly the uterus and fallopian tubes, at the cellular level. As they create a larger atlas, scientists hope to fill some of the major gaps in research on the female body to expand our understanding of what a healthy female reproductive system entails.
More recently, researchers from the Wellcome Sanger Institute and the University of Oxford have created a map of the endometrium, the lining of the womb, to potentially improve treatment and diagnosis of endometriosis. Ideally, the researchers from both “map” studies would work together, using the data from their atlases to continue to expand their understanding of the female reproductive system and improve the treatment of reproductive disorders overall.
The bottom line
With this new research laying out a cellular level map of the ovary, scientists are better able to understand ovarian function (specifically healthy follicular development), which will hopefully lead to better treatment for female reproductive disorders. It could also potentially lead to the creation of artificial ovaries for women suffering from ovarian disorders, or whose ovarian health has been negatively impacted by cancer treatments. Further research is needed to fully understand the process of developing these treatments, and any health or ethical implications they raise. Hopefully, this new knowledge will be used to provide women with the quality health care they deserve, treating their health issues at the source.
