This Rodent Has A Menstrual Cycle Similar to a Human Female’s, Could Be Used In Studying Reproductive Disorders

Scientists have found a rodent that has a menstrual cycle similar to that of human females.

Researchers at the Monash University in Clayton, Australia said that the spiny mouse (Acomys cahirinus) is the first rodent species known to menstruate and also seem to have a human-like menstrual cycle.

Mice are often used in biomedical research laboratories. But since they don't menstruate, they make poor models for studying women's reproductive health.

But as it turns out, not all mice are created equal.

In the study, which was published in bioRvix, researchers tracked the periods of 14 female spiny mice. They flushed the animals' genitals with saline solution daily for 18 days. To ensure that the procedure was not the cause of the bleeding, the researchers treated five common lab mice the same way.

They found that the mice averaged a 9-day menstrual cycle similar to human females, and three of the nine days - which represent 20 to 30 percent of their cycle - were spent shedding uterine lining or bleeding.

This ratio is similar to that in women, who typically bleed 15 to 35 percent of their 28-day cycle, Nature.com reports.

The researchers also dissected uteri from four spiny mice at different stages of the menstrual cycle.

In a statement published in PopSci.com, the researchers are hoping that the spiny mice could be a model for studying human menstruation and menstrual disorders.

Warren Nothnick, a researcher at the University of Kansas, told Nature.com that this discovery could help current studies involving endometriosis, a painful disorder in which a tissue that normally lines the inside of the uterus grows outside of the uterus.

The current model for studying endometriosis, the baboon, is more expensive and time-consuming, and menstruating laboratory mice could be a better alternative.

Nothnick considers it a "major breakthrough" if the researchers could identify if the mice would develop endometriosis. "There's some really simple studies that they could do to see if these animals would develop endometriosis spontaneously," he said.

Endometriosis is known to affect 6.3 million women and girls in the U.S., 1 million in Canada, and millions more around the world.