urogenital opening

{{Short description|Body part in some animals}}

File:Anatomytool Male and female urinary tract English.jpg through an opening in the penis or vulva.]]

The urogenital opening is where bodily waste and reproductive fluids are expelled to the environment outside of the body cavity. In some organisms, including monotremes,{{Cite book |last1=Withers |first1=Philip C. |url=https://books.google.com/books?id=CcNjDQAAQBAJ&pg=PA275 |title=Ecological and Environmental Physiology of Mammals |last2=Cooper |first2=Christine E. |last3=Maloney |first3=Shane K. |last4=Bozinovic |first4=Francisco |last5=Neto |first5=Ariovaldo P. Cruz |date=2016-10-27 |publisher=Oxford University Press |isbn=978-0-19-109267-1 |language=en}} birds and some fish, discharge from the urological, digestive, and reproductive systems empty into a common sac called the cloaca.

In most mammals, these three systems are more separated. In females (specifically primates and rodents), separate orifices have evolved for all three, while males discharge urine and semen from the urethra through a common urinary meatus.{{cite book|author=Libbie Henrietta Hyman|title=Hyman's Comparative Vertebrate Anatomy|url=https://books.google.com/books?id=VKlWjdOkiMwC&pg=PA583|date=15 September 1992|publisher=University of Chicago Press|isbn=978-0-226-87013-7|pages=583–}} In marsupials{{Cite book |last=Nowak |first=Ronald M. |url=https://books.google.com/books?id=ldXtY8ppxSQC&pg=PA14 |title=Walker's Marsupials of the World |date=2005-09-12 |publisher=JHU Press |isbn=978-0-8018-8211-1 |language=en}}{{Cite book |last1=Withers |first1=Philip C. |url=https://books.google.com/books?id=CcNjDQAAQBAJ&dq=%22Urogenital+opening%22&pg=PA275 |title=Ecological and Environmental Physiology of Mammals |last2=Cooper |first2=Christine E. |last3=Maloney |first3=Shane K. |last4=Bozinovic |first4=Francisco |last5=Neto |first5=Ariovaldo P. Cruz |date=2016-10-27 |publisher=Oxford University Press |isbn=978-0-19-109267-1 |language=en}} and most placentals, the female urethra and vagina open into a urogenital sinus with a common urogenital opening (vulvar opening in placentals).{{Cite book |last1=Smith |first1=David G. |url=https://books.google.com/books?id=nZDqAgAAQBAJ&dq=%22Urogenital+opening%22&pg=PA491 |title=Exploring Zoology: A Laboratory Guide |last2=Schenk |first2=Michael P. |date=2014-01-01 |publisher=Morton Publishing Company |isbn=978-1-61731-157-4 |language=en}}