Archive · 20 Aug 2026
Scientists Advance Lab-Grown Gametes While Synthetic Humans Remain Distant
Scientists are trying to make early sperm and egg cells in laboratories.
They start with ordinary cells, such as blood or skin cells, and reprogram them into stem cells.
These stem cells can potentially become many different cell types.
One research team created very early sperm-making cells, but not working sperm.
The cells were grown in special tissue placed inside mice.
Scientists have also made working mouse eggs from skin cells in other experiments.
Human reproduction is much more complicated and takes longer than mouse reproduction.
Researchers still need to understand how to control important DNA changes and the cells that support developing sperm and eggs.
For now, laboratory-made human sperm and eggs are not safe or ready for reproduction, and fully lab-grown humans remain far away.
Researchers are using induced pluripotent stem cells to recreate early human reproductive development outside the body.
A University of Pennsylvania team produced human spermatogonia from blood-derived stem cells in tissue structures implanted in mice.
The cells did not mature into functional sperm capable of fertilization.
Scientists are developing organoids, artificial testicular tubules and organ-on-chip systems to reproduce the reproductive environment.
Potential medical uses include fertility options for cancer survivors and same-sex couples, but major safety and ethical barriers remain.
- Who
- Researchers in stem-cell and reproductive biology, including a University of Pennsylvania team led by developmental biologist Kotaro Sasaki and work by Katsuhiko Hayashi’s laboratory.
- What
- Scientists are attempting to recreate human gamete development in laboratories through in vitro gametogenesis, but have not produced functional human sperm or eggs or fully formed humans.
- When
- The article describes current research and possible future developments; no specific publication date is provided.
- Where
- Research has taken place in laboratory systems, including tissue structures grown on the kidneys of mice; the University of Pennsylvania team is identified as a leading group.
- Why
- The research could improve understanding of human development and eventually offer fertility options for people who cannot produce viable gametes.
Potential Medical and Scientific Benefits
Safety and Ethical Concerns
Fertility treatment
Potential Medical and Scientific Benefits
IVG could eventually help cancer survivors who lost fertility and could allow same-sex couples to have offspring genetically related to both parents.
Safety and Ethical Concerns
The article says laboratory-generated human gametes are currently unsuitable for reproduction and would require extensive safety testing before clinical use.
Recreating reproduction
Potential Medical and Scientific Benefits
Organoids and organ-on-chip systems may help scientists understand human reproductive development more closely than existing models.
Safety and Ethical Concerns
Human gamete development involves complex support cells, epigenetic changes and long-term interactions that researchers have not yet fully reproduced.
Future embryo creation
Potential Medical and Scientific Benefits
If made safe, IVG could potentially reduce repeated hormone treatments and surgical egg retrievals in some IVF procedures.
Safety and Ethical Concerns
Generating hundreds or thousands of embryos from one person’s cells raises ethical concerns, while broader reproductive development and pregnancy processes remain poorly understood.
- Core technology
- In vitro gametogenesis produces sperm or eggs outside the body from ordinary cells such as skin or blood cells.
- Cell source
- Researchers use induced pluripotent stem cells, which are adult cells reprogrammed into an embryonic-like state.
- Human research milestone
- Blood-derived stem cells were developed into spermatogonia, the earliest precursors of sperm.
- Current limitation
- The laboratory-grown human cells did not become functional sperm capable of fertilization.
- Mouse achievement
- Katsuhiko Hayashi’s laboratory generated functional mouse eggs from skin cells and reported healthy offspring from two biological fathers.
- Potential applications
- Possible future uses include fertility treatment for cancer survivors, same-sex couples and people seeking alternatives to conventional IVF procedures.
- Main concerns
- Researchers identify epigenetic reprogramming, reproductive support systems, embryonic development, safety testing and ethical oversight as major challenges.