Behaviour 2019
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Open for business: Some female pouched rats lack a vaginal opening; only those with open vaginas are choosy
Angela Freeman1, Soon Hon Cheong1, Jeremy Allen1, Assaf Lerer1, Bhupinder Singh1, Bryant Blank1, Dean Jeffery1, Danielle Lee1,2, Alexander Ophir1. 1Cornell University, Ithaca, NY, United States; 2Southern Illinois University Edwardsville, Edwardsville, IL, United States

Sexual maturation is associated with changes in reproductive morphology and behavior. In some mammals, the opening of the vagina (patency) is delayed after birth, but patency is almost always realized by adulthood. In African giant pouched rats (Cricetomys ansorgei) some females delay patency for several years even though they are ‘adult’ by all other metrics. Here we describe how non-patent and patent females differ. Using x-ray and magnetic resonance imaging, we found measurable differences in internal and external reproductive organs, with non-patent females showing underdeveloped reproductive morphology. We examined female hormonal state and found estradiol was greater in patent females compared to non-patent females. Females in each reproductive state also differed in their urine metabolomic content, indicating that they could smell differently to males. Finally, patent females spend significantly less time investigating the urine of non-masculinized males, suggesting that reproductively available females are choosier among potential mates. What causes females to become reproductively available remains unclear, but we suggest that it is a socially-modulated characteristic.