Editing Placenta (section)

==Evolution and phylogenetic diversity==
The placenta has evolved independently multiple times, probably starting in [[fish]], where it originated multiple times, including the genus ''[[Poeciliopsis]].''<ref>{{cite journal | vauthors = Reznick DN, Mateos M, Springer MS | title = Independent origins and rapid evolution of the placenta in the fish genus Poeciliopsis | journal = Science | volume = 298 | issue = 5595 | pages = 1018–1020 | date = November 2002 | pmid = 12411703 | doi = 10.1126/science.1076018 | bibcode = 2002Sci...298.1018R | s2cid = 2372572 }}</ref> Placentation has also evolved in some [[reptile]]s.<ref>{{cite journal | vauthors = Blackburn DG, Avanzati AM, Paulesu L | title = Classics revisited. History of reptile placentology: Studiati's early account of placentation in a viviparous lizard | journal = Placenta | volume = 36 | issue = 11 | pages = 1207–1211 | date = November 2015 | pmid = 26474917 | doi = 10.1016/j.placenta.2015.09.013 }}</ref>

The '''mammalian placenta''' evolved more than 100 million years ago and was a critical factor in the explosive diversification of placental mammals.<ref>{{cite journal | vauthors = Ayala FJ | title = Darwin's greatest discovery: design without designer | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 104 | issue = Suppl 1 | pages = 8567–8573 | date = May 2007 | pmid = 17494753 | pmc = 1876431 | doi = 10.1073/pnas.0701072104 | doi-access = free }}</ref> Although all mammalian placentas have the same functions, there are important differences in structure and function in different groups of mammals. For example, human, bovine, equine and canine placentas are very different at both the gross and the microscopic levels. Placentas of these species also differ in their ability to provide maternal [[Antibody|immunoglobulins]] to the fetus.<ref>{{cite web | vauthors = Bowen R | url = http://www.vivo.colostate.edu/hbooks/pathphys/reprod/placenta/index.html | title = Implantation and Development of the Placenta: Introduction and Index. | work = Pathophysiology of the Reproductive System | publisher = Colorado State | access-date = 7 July 2019 }}</ref>