Urogenital opening

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,^[1] birds and many 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 in males, a common urinary meatus discharges both urine and semen from the urethra.^[2] In marsupials^[3]^[4] and most placentals, the female urethra and vagina open into a urogenital sinus with a common urogenital opening (vulvar opening in placentals).^[5]

References

^ Withers, Philip C.; Cooper, Christine E.; Maloney, Shane K.; Bozinovic, Francisco; Neto, Ariovaldo P. Cruz (2016-10-27). Ecological and Environmental Physiology of Mammals. Oxford University Press. ISBN 978-0-19-109267-1.
^ Libbie Henrietta Hyman (15 September 1992). Hyman's Comparative Vertebrate Anatomy. University of Chicago Press. pp. 583–. ISBN 978-0-226-87013-7.
^ Nowak, Ronald M. (2005-09-12). Walker's Marsupials of the World. JHU Press. ISBN 978-0-8018-8211-1.
^ Withers, Philip C.; Cooper, Christine E.; Maloney, Shane K.; Bozinovic, Francisco; Neto, Ariovaldo P. Cruz (2016-10-27). Ecological and Environmental Physiology of Mammals. Oxford University Press. ISBN 978-0-19-109267-1.
^ Smith, David G.; Schenk, Michael P. (2014-01-01). Exploring Zoology: A Laboratory Guide. Morton Publishing Company. ISBN 978-1-61731-157-4.

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