Rather unfortunate discovery for the mice concerned

First rodent found with a human-like menstrual cycle : Nature News & Comment

Mice are a mainstay of biomedical research laboratories. But the rodents are poor models for studying women’s reproductive health, because they don’t menstruate.

Now
researchers at Monash University in Clayton, Australia, say that they
have found a rodent that defies this conventional wisdom: the spiny
mouse (Acomys cahirinus). If the finding holds up, the animal could one day be used to research women's menstruation-related health conditions.