os clitoridis

The os clitoridis was described in 1666 by Claude Perrault in otters and in the lioness.{{cite book|author=Claude Perrault|title=Mémoires pour servir à l'histoire naturelle des animaux|url=https://books.google.com/books?id=GPwRVJHMMl4C|year=1748|publisher=Arkstee & Merkus|lang=fr}}

The term os clitoridis was used in 1819 by Friedrich Sigismund Leuckart regarding the capuchin monkey.{{Google books|H_pAAAAAcAAJ|Zoologische Bruchstücke|page= 41|highlight=clitoridis|author=Friedrich Sigismund|year=1819|publisher=Leuckart|lang=de}}

This bone was named baubellum by Guy Chester Shortridge in 1934,{{cite book|first=G. C.|last=Shortridge|title=The mammals of South West Africa|year=1934|publisher=William Heinemann Ltd}} but it is much less common in comparison to the use of the word baculum. The Latin terms os clitoris and os clitoridis are most often found in scientific publications.

The os clitoridis has been described in species belonging to the orders Chiroptera, Primates, Rodentia and Carnivora.{{Cite journal|title=The os clitoridis of some North American Sciuridae|author=James N. Layne|journal=Journal of Mammalogy|volume=35|number=3|date=August 1954|pages=357–366 |doi=10.2307/1375960 |jstor=1375960 |url=https://www.jstor.org/stable/1375960|access-date=September 21, 2022}} As with the baculum, this wide distribution suggests a primitive character that has been lost in some phylogenetic branches of the class Mammalia.

Depending on the species, the presence of this bone varies from one specimen to another. It has been observed, for example, in only 30% of American red squirrels.{{Cite journal|title=The os genitale of the red quirrel, Tamiasciurus|journal=Journal of Mammalogy|volume=33|date=1952|author=James N. Layne|number=4|pages=457–459 |doi=10.2307/1376017 |jstor=1376017 |url=https://www.jstor.org/stable/1376017|access-date=21 September 2022}} Its presence is even rarer in dogs: 3% (6 out of 200) presence on a radiological sample of American Cocker Spaniels and 2% (4 out of 200) for the German Shorthaired Pointer.{{cite conference|title=Os clitoridis incidence on radiographs submitted for coxofemoral dysplasia evaluations|conference=International Symposium on Canine and Feline Reproduction {{!}} IVIS| author=Kutzler M.|author2=Keller G.G.|author3=Smith F.|website=www.ivis.org|url=https://www.ivis.org/library/iscfr|date=2020-01-11|access-date=2022-09-21}}

The shape and size vary greatly from one species to another. The size is often very small:All measurements listed below are less than an inch, with the exception of the walrus, which can be up to 1 inch.

• 2 x 6 mm in the mountain beaver{{cite journal|title=Aplodontia rufa|journal=Mammalian Species|volume=431|date=April 23, 1993|url=http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-431-01-0001.pdf|pages=1–10}}
• 2 x 0.4 x 0.2 mm in an adult lioness{{cite book|author=H. Burrows|title=Biological Actions of Sex Hormones|page=226|url=https://books.google.com/books?id=IVWyAAAAQBAJ&dq=os+clitoridis&pg=PA227|year=2013|publisher=Cambridge University Press|isbn=978-1-107-62550-1}}
• 0.5 x 0.05 x 0.01 mm in a 3-year-old adult cat
• From 10 to 30 mm in a walrus{{cite book|author=Leonard Janet |author2=Alex Cordoba-Aguilar|title=The Evolution of Primary Sexual Characters in Animals|url=https://books.google.com/books?id=PgtXj5R6OfMC&q=clitoris&pg=PA491|year=2010|publisher=Cambridge University Press|isbn=978-0-19-971703-3}} (note that the male of this species has the longest baculum, with a size of 63 cm (24 inches))
• 9.3 mm in the American badger{{cite book|last=WH|title=Bacula of North American Mammals|url= http://deepblue.lib.umich.edu/handle/2027.42/56357|year=1960|publisher=Museum of Zoology, University of Michigan|hdl=2027.42/56357 }}

The os clitoridis is often present, or even prominent, during the embryonic or immature phase, and then decreases with age. For example, in a walrus, the size of the bone tends to shrink as the years pass.

The exact function of the os clitoridis is not known, but a function during copulation is assumed.{{cite book|author=Pascal Picq|author2 = Philippe Brenot|title=Le Sexe, l'Homme et l'Évolution|url= https://books.google.com/books?id=rttHAwAAQBAJ&dq=%22os+clitoridien%22&pg=PA234|year=2009| publisher=Odile Jacob |editor=Odile Jacob|lang=fr|isbn=9782738195661}} For some, the species distribution would be the same as the baculum. The os clitoridis would be an equivalent, without evolutionary function, of the baculum, persisting or disappearing during sexual differentiation under hormonal influence. Experiments with treatment of the spleen with testosterone, led to a persistence or increase in the size of the os clitoridis.{{Google books|y-RWPGDONlIC|title=Bones and Cartilage: Developmental and Evolutionary Skeletal Biology|page=344|highlight=os+clitoridis|author= Brian K. Hall|year=2005|publisher=Academic Press}}

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Category:Clitoris

Category:Mammal anatomy

Category:Mammal female reproductive system