Updated November 1, 2026: I rewrote this post to add news since it went up. New material covers the 2023 mouse eggs from male cells, the 2024 Saitou reprogramming paper, the 2025 two-father mice, a company’s 2025 human-egg claim, and the 2026 ASRM ethics opinion.
Introduction
In vitro fertilization turned 47 this year. Once a fringe experiment, IVF is now a routine service that has produced more than ten million births. Yet it still runs into one hard limit, the human egg. A woman’s supply is fixed at birth, and donation is invasive, costly and fraught. A newer line of work, lab made human eggs, could one day remove that limit.
I wrote earlier about artificial wombs and how they might change reproduction. Lab made human eggs sit beside them. Both are technologies that would move reproductive control away from the body’s limits and toward systems we design.
Can we make eggs in the lab, the way IVF makes embryos? The idea is called in vitro gametogenesis, or IVG. It imagines growing new eggs or sperm from ordinary body cells. If it works, it would change who can have children, at what age, and with whose DNA.
This is no longer pure speculation. In 2025, a team at Oregon Health and Science University pushed human cells partway through egg formation. Shoukhrat Mitalipov led it, with Núria Martí-Gutiérrez and Alexandra Mikhalchenko. Their Nature Communications paper took IVG a real step closer to lab made human eggs than anyone had managed before.
Why scientists want lab made human eggs
Eggs are scarce and fragile. Unlike sperm, a woman cannot make more of them, and collecting them means hormone injections and surgery. Age, early menopause, and cancer treatments that destroy ovarian tissue all cut the supply short.
If scientists could grow lab made human eggs from skin or blood cells, the payoff would be large. People who cannot make their own eggs could have genetically related children. Same-sex couples could have a child sharing DNA from both partners. Cancer survivors could become parents with their own cells. The same tools would also allow gene editing, to fix inherited disease or, more controversially, to enhance traits.
These are real possibilities, and they carry real questions. What happens when reproduction no longer bends to the body’s limits? How do we weigh what is possible against what is wise?
The Mitalipov team’s approach
The Mitalipov team started with two ingredients, a donated human egg and a human skin cell. They pulled the DNA-filled nucleus out of the egg and dropped in the nucleus from the skin cell. The egg’s cytoplasm, the material around the nucleus, carries machinery that can reset a cell’s DNA.
Then came the hard part. They coaxed that transplanted nucleus to shed half its chromosomes, the defining move of egg formation. They fertilized the rebuilt eggs with sperm and watched. Of 82 reconstructed eggs, about 9% reached the blastocyst stage, the earliest ball of embryonic cells. None went further. Most carried too many or too few chromosomes.
Even so, the result showed something new. An adult cell’s DNA can, in rare cases, be reset enough to start an embryo. It is a proof of principle, not a route to pregnancy, but it is the first credible step toward a working lab made human egg.
Two routes to lab made human eggs
Researchers see two main roads.
The stem-cell route
This path turns a skin or blood cell into a pluripotent stem cell, a blank slate that can become any cell type. Scientists then walk it through the stages of egg formation: germ cells, then early egg precursors, then mature eggs. In mice, that full path already works and has produced live pups. In humans, the later steps, where chromosomes pair and split in meiosis, remain hard to control.
The field’s biggest recent advance came here. In 2024, Mitinori Saitou’s lab in Kyoto reported how to drive the epigenetic reprogramming that human germ cells need. In their Nature paper, a signal called BMP reset the chemical marks on the DNA and pushed the cells into oogonia-like cells, an early egg stage. Those cells then multiplied more than ten billion-fold. Getting them through meiosis to a mature egg is the next wall.
One company says it has started up that wall. In 2025, Conception, a secretive California startup, reported building stem-cell-derived mini-ovaries that hold early human egg cells entering meiosis. The claim is company-reported, not peer-reviewed, and outside scientists have asked for more evidence. I would treat it as a marker of where the money is going, not as a result you can bank on.
The nuclear-transfer shortcut
OHSU uses this second road. Rather than build an egg from scratch, it borrows a donated egg as a living reactor. A skin-cell nucleus goes in, and the egg’s machinery tries to reprogram it. The two challenges are forcing the chromosomes to halve cleanly and resetting the epigenetic marks, the chemical labels that decide which genes switch on.
Why lab made human eggs are hard
Three problems stand out.
Meiosis has to be perfect. Every chromosome must separate correctly. A single error can stop development cold.
Epigenetic reprogramming has to be complete. Each germ cell must wipe and rebuild the marks that guide development. So far that reset is patchy.
Quality control is unsettled. The field has no agreed test for a “functional” egg. Checks for chromosome count, imprinting and mitochondrial health exist, but no standard ties them together.
What lab made human eggs would change
Clear these walls and lab made human eggs could reshape fertility medicine. They would restore fertility after cancer or early menopause. They would give same-sex couples a genetically shared child, cut the need for invasive donation, and allow editing out inherited disease. The same door opens onto enhancement, which is where the ethics get sharp.
The promise comes with a duty to go slow. Biology does not forgive sloppy work. Each step, chromosome sorting, reprogramming, fertilization, has to be near flawless before anyone tries this in a clinic.
Timelines and hype
Some boosters predict lab made human eggs within a decade. The OHSU work suggests a longer arc. The progress is real but shaky. Expect years of slow gains before anyone can fairly call this medicine rather than experiment. The clearest recent example of that gap is the mouse record, which runs well ahead of the human one.
Rules and ethics catching up
Oversight is starting to move. The International Society for Stem Cell Research updated its guidelines in 2025 to cover embryo-like research and IVG. The Nuffield Council on Bioethics put out a policy brief on consent, regulation and cross-border oversight. In 2026, the American Society for Reproductive Medicine went further. Its ethics opinion said IVG should not be used to make a baby until it has been tested thoroughly in nonhuman primates. Governments will lean on all three as they write law.
Some questions still need a public airing:
- Who can donate eggs for research?
- How do labs stop someone’s cells being turned into gametes without consent?
- What benchmarks define a safe lab made human egg?
What the mouse work shows
Mice got here first, and their record is the best guide to what is technically possible.
In 2012, Katsuhiko Hayashi’s team in Japan made healthy pups from eggs derived from stem cells, fertilized with ordinary sperm. A year earlier the same group had made stem-cell sperm that fathered pups. Then in 2016 the lab grew mouse eggs entirely in a dish, from stem cell to mature egg. Those eggs also made healthy pups.
The work kept going. In 2023, Hayashi’s team made eggs from the skin cells of male mice. They turned XY cells into XX cells and grew eggs from them. Seven live pups came from 630 embryos, a rate just over 1%. In principle, two males could be the genetic parents of a pup.
Two fathers, two methods
A different Chinese group took another route to two fathers. In January 2025, a team at the Chinese Academy of Sciences used CRISPR to edit 20 imprinted genes. Those genes normally need one copy from each parent. Zhi-Kun Li and Wei Li led the work. They combined two sperm genomes and produced bipaternal mice that reached adulthood. Only about 12% of embryos became live mice, and those mice were sterile and often unhealthy. It is a striking result, and a reminder of how much imprinting resists this kind of engineering.
Earlier work had already made two-mother mice. In 2004, Tomohiro Kono’s group reprogrammed the marks that separate maternal and paternal DNA and produced pups with two genetic mothers. Together these experiments show both eggs and sperm can, in principle, be rebuilt from ordinary cells.
The animal record proves the logic of IVG. It also shows the gap between species. Human egg and sperm development is slower, more complex, and less forgiving of errors in chromosome handling and imprinting. The mouse work tells us what is possible, not yet what is safe.
The next frontier: lab-made sperm
Most attention goes to eggs, but the same logic applies to sperm. Early experiments in mice and in human cell cultures have already produced immature sperm-like cells from stem cells. In mice, some of those cells have fertilized eggs and made live offspring.
If that reaches humans, it would close the loop, both egg and sperm grown from ordinary cells. That would open same-sex reproduction, fertility after testicular failure, and gene editing of the germ line. Each raises hard questions about identity and inheritance.
The same caution holds as for eggs. Success depends on error-free meiosis, faithful imprinting, and exhaustive testing before any clinical use. The groundwork, though, is laid.
My take
The OHSU result is both thrilling and sobering. It proves egg cytoplasm can reprogram adult DNA, and it proves how fiercely nature guards reproduction. The road from proof to practice will take careful engineering and open oversight.
Handled well, lab made human eggs could be the next chapter in the story IVF began. They would turn reproductive biology into something we can repair, and perhaps one day redesign. Handled badly, it is a fast route to harm. The science will not decide which we get. We will.
Your thoughts about lab made human eggs?
I am curious where you land. Lab made human eggs could remake fertility care, widen who can be a genetic parent, and open the germ line to editing. They also raise hard questions about safety, identity and how far this should go.
A few to chew on:
- Would you support clinical use once the science is proven safe?
- How should labs guard against making gametes from someone’s cells without consent?
- Should age limits apply if eggs and sperm can come from any cell?
- How do you feel about same-sex genetic reproduction?
- Is it acceptable to edit these gametes to cure disease? To enhance traits?
Leave a comment. I read every one, and your feedback shapes future posts.
Recommended by Bleeding Edge Biology
Want to go deeper on lab made human eggs and the science reshaping reproduction? These are the papers, talks and films I would start with.
Primary papers
- Martí-Gutiérrez, Mikhalchenko et al. (2025). Induction of experimental cell division to generate cells with reduced chromosome ploidy. Nature Communications 16, 8340.
The OHSU nuclear-transfer study behind this post. It reports a reductive division method, which the team calls mitomeiosis, and early embryo formation. - Murase, Saitou et al. (2024). In vitro reconstitution of epigenetic reprogramming in the human germ line. Nature 631, 170-178.
The key advance on the stem-cell route. BMP signaling drives human germ cells into oogonia-like cells that expand enormously. - Hayashi et al. (2023). Generation of functional oocytes from male mice in vitro. Nature 615, 900-906.
Eggs grown from the cells of male mice, which produced live pups. - Hikabe, Hayashi et al. (2016). Reconstitution in vitro of the entire cycle of the mouse female germ line. Nature 539, 299-303.
The first complete female germ-line cycle in a dish, start to finish, with live births. - Kono et al. (2004). Birth of parthenogenetic mice that can develop to adulthood. Nature 428, 860-864.
Two-mother mice, made by reprogramming imprinted genes.
Reviews and ethics
- de Bruin et al. (2025). Stem cell-derived gametes: what to expect when expecting their clinical introduction. Human Reproduction 40(9), 1605-1615.
A clear-eyed review of the risks and the follow-up studies clinical use would demand. - Le Goff et al. (2024). Anticipating in vitro gametogenesis. Stem Cell Reports 19, 933-945.
Stakeholder views on IVG, including from LGBTQ+ communities, on safety and access. - ASRM Ethics Committee (2026). Ethical considerations of in vitro gametogenesis.
The American fertility society’s position: no reproductive use until primate studies are done. - Nuffield Council on Bioethics (2025). In vitro gametogenesis: a review of ethical and policy questions.
A practical overview of the legal and social issues.
Talks and film
- Jennifer Doudna: How CRISPR lets us edit our DNA
Background on the gene-editing tools behind next-generation reproduction. - Marcy Darnovsky: Use gene editing to treat patients, not design babies
An ethicist’s sharp take on reproductive biotech. - Human Nature (2019)
A documentary on CRISPR and what gene editing means for people. - Make People Better (2022)
On the first gene-edited babies case, and the ethics around it.
