Bulbus glandis

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Not to be confused with Bulbourethral gland or Bulb of penis.
Erect bulbus glandis (1) in a Labrador Retriever

The bulbus glandis (also called a knot) is an erectile tissue structure on the penis of canid mammals.[1][2][3][4][5][6] During mating the tissues swell up and lock (tie) immediately after penetration of the male's penis inside the female. The locking is completed by circular muscles just inside the female's vagina tightening thus preventing the male from withdrawing. The circular muscles also contract intermittently, which has the effect of stimulating ejaculation of sperm, followed by prostatic fluid, as well as maintaining the swelling of the penis and therefore the tie, for some time. For domestic dogs the tie may last up to half an hour or more, though usually less.[7]

The bulbus glandis also occurs in the penises of some pinnipeds, including South American fur seals.[8]

See also[edit]


  1. ^ MobileReference (15 December 2009). The Illustrated Encyclopedia of North American Mammals: A Comprehensive Guide to Mammals of North America. MobileReference. pp. 977–. ISBN 978-1-60501-279-7. Retrieved 10 December 2012. 
  2. ^ Kim Long (1996). Wolves: A Wildlife Handbook. Big Earth Pub. ISBN 978-1-55566-158-8. Retrieved 10 December 2012. 
  3. ^ L. David Mech (16 May 2012). Wolf. Random House Digital, Inc. pp. 172–. ISBN 978-0-307-81913-0. Retrieved 10 December 2012. 
  4. ^ Marshall Cavendish Corporation (1 September 2010). Mammal Anatomy: An Illustrated Guide. Marshall Cavendish. pp. 252–. ISBN 978-0-7614-7882-9. Retrieved 10 December 2012. 
  5. ^ Debra A. Carlson (2008). Reproductive Biology of the Coyote (Canis Latrans): Integration of Behavior and Physiology. ProQuest. pp. 67–. ISBN 978-0-549-50315-6. Retrieved 9 February 2013. 
  6. ^ H. M. Menino (2008). Darwin's Fox and My Coyote. University of Virginia Press. pp. 101–. ISBN 978-0-8139-2675-9. Retrieved 9 February 2013. 
  7. ^ Susan Long (2006). Veterinary Genetics and Reproductive Physiology. Churchill Livingstone Elsevier. ISBN 978-0-7506-8877-2. 
  8. ^ http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-736X2012001300013&lng=es&nrm=iso&tlng=es