Scientists create the first mice that can menstruate
In a groundbreaking advance for reproductive biology, scientists have developed the first laboratory mouse model that experiences menstruation in a way that closely resembles the human process. The discovery could transform menstrual health research by allowing scientists to study in detail how the uterus breaks down, sheds, and regenerates each cycle.
Menstruation is a highly coordinated process. Each month, the lining of the uterus builds up to prepare for a possible pregnancy. If no fertilised egg implants, part of this lining is shed while a deeper layer remains to rebuild it for the next cycle. Understanding exactly how this separation and repair occur has been difficult because ordinary laboratory animals, including mice, do not menstruate.
To solve this, researchers at Harvard University engineered the uterine lining of standard lab mice to carry a special receptor that can be switched on by a harmless drug. Turning on this receptor boosts calcium signalling inside endometrial cells, which is one of the cues that drives the tissue into a premenstrual state. The team first raised progesterone to mimic the post-ovulation phase and later withdrew it. With the receptor activated at the right moment, the uterine lining thickened, then broke down and was shed over several days, closely mirroring a human period.
When the team analysed the tissue, they found patterns that match those of human menstruation, including blood vessel expansion, immune activity, and gene expression programs observed in people. Using single-cell spatial transcriptomics, they also observed a layered organisation of cells in the lining. Younger, regenerative cells formed rings around older, dying cells. This arrangement may help the uterus shed efficiently and then repair without scarring.
The study reframes how menstrual shedding is organised and gives scientists a precise, controllable model for investigating conditions such as endometriosis, adenomyosis, and heavy menstrual bleeding. Although not every human feature is present, such as the spiral arteries unique to the human uterus, this work represents a major step forward.
The findings were published as a preprint, meaning they are still awaiting peer review, but they already signal a major shift in the field. Having a reliable model for menstruation could accelerate discoveries in women’s health, from understanding endometrial biology to developing better treatments for reproductive and inflammatory disorders. It highlights how advancing basic research can profoundly shape how we approach menstrual health and disease.
Reference
Çevrim, Ç., Hilgert, N. J., Kaage, A. M., Russell, A. J. C., Goldstein, A. E., Ang, C. J., Gable, J. L. R., Bagamery, L. E., Breznik, A., Di Bella, D. J., Talay, M., Peng, J., O’Neill, K. E., Chen, F., Eddy, S. R., & McKinley, K. L. (2025). Induction of menstruation in mice reveals the regulation of menstrual shedding. bioRxiv. https://doi.org/10.1101/2025.10.08.681007
