Reproduction Abstracts

Background: Menstruation, the cyclical breakdown of the superficial endometrial layer in the absence of pregnancy, occurs in 1.5% of mammals. There is no obvious phylogenetic link between species known to menstruate: humans, Old World monkeys, some bats and the elephant shrew, and true menstruation has never before been reported in rodents. Observations of blood at the vaginal opening in some females, led us to examine the possibility that the spiny mouse (Acomys cahirinus...