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Updated: Jul 15, 2026
09:01
Performing Vaginal Lavage, Crystal Violet Staining, and Vaginal Cytological Evaluation for Mouse Estrous Cycle Staging Identification
Published on: September 15, 2012
Why do women menstruate? Historical and evolutionary review
1Department of Veterinary Preclinical Sciences, University of Liverpool Veterinary Field Station, Leahurst, Cheshire, UK. finn@liv.ac.uk
European Journal of Obstetrics, Gynecology, and Reproductive Biology
|December 1, 1996
Summary
Menstruation evolved from early vertebrate reproductive strategies, involving uterine changes and immune adaptations to manage fetal genetic differences. Progesterone is key in preventing inflammatory rejection of the embryo, with its drop triggering menstruation when pregnancy doesn't occur.
Area of Science:
- Reproductive Biology
- Evolutionary Medicine
- Comparative Anatomy
Background:
- Menstruation theories span from ancient to modern perspectives.
- Uterine evolution is traced from jawed fishes through mammals.
- Internal fertilization and embryonic development present unique evolutionary challenges.
Observation:
- The evolution of oviducts facilitated internal fertilization and embryonic protection.
- Viviparous animals evolved mechanisms to manage genetic disparities between mother and embryo.
- Progesterone plays a crucial role in modulating maternal immune responses during pregnancy.
Findings:
- Mammalian blastocysts, like the mouse's, can invade the endometrium.
- The decidual reaction in mammals resembles inflammatory granulation tissue.
- In women, a similar reaction occurs during the luteal phase, anticipating blastocyst implantation.
Implications:
- Understanding menstruation provides insights into reproductive immunology and evolutionary adaptations.
- The progesterone-mediated suppression of inflammation is critical for successful pregnancy.
- The shedding of uterine lining during menstruation highlights the cyclical nature of reproductive readiness.
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