The placenta of humans, and certain other mammals contains structures known as cotyledons, which transmit fetal blood and allow exchange of oxygen and nutrients with the maternal blood.
| Placental cotyledon | |
|---|---|
 Structure of the placenta, with a placental cotyledon marked in rectangle. | |
| Anatomical terminology |
Ruminants
editThe Artiodactyla have a cotyledonary placenta. In this form of placenta, the chorionic villi form a number of separate circular structures (cotyledons) which are distributed over the surface of the chorionic sac.[1] Sheep, goats and cattle have between 75 and 125 cotyledons whereas deer have four to six larger cotyledons.[2][3]
Human
editThe form of the human placenta is generally classified as a discoid placenta. Within this, the cotyledons are the approximately 15 to 25 separations of the decidua basalis of the placenta, separated by placental septa.[4] Each cotyledon consists of a main stem of a chorionic villus as well as its branches and sub-branches.[4]
Vasculature
editThe cotyledons receive fetal blood from chorionic vessels, which branch off cotyledon vessels into the cotyledons, which, in turn, branch into capillaries.[5] The cotyledons are surrounded by maternal blood, which can exchange oxygen and nutrients with the fetal blood in the capillaries.
References
edit- ↑ Kurt Benirschke (2007). "Placentation". Comparative Placentation. Retrieved 26 February 2026.
- ↑ R. Bowen (8 August 2000). "Placentation in Ruminants (Cattle, sheep, ..)". Hypertexts for Biomedical Sciences: Implantation and Development of the Placenta. Retrieved 26 February 2026.
- ↑ Erick Conard (2002). "Cotyledonary Placenta: An Easy To Understand Explanation". Erick Conard's Lucky Hit Ranch. Retrieved 26 February 2026.
- 1 2 Page 565 in: Varney, Helen; Helen Varney Burst; Kriebs, Jan M.; Gegor, Carolyn L. (2004). Varney's midwifery. Boston: Jones and Bartlett Publishers. ISBN 0-7637-1856-4.
- ↑ Gordon, Z.; Elad, D.; Almog, R.; Hazan, Y.; Jaffa, A. J.; Eytan, O. (2007). "Anthropometry of fetal vasculature in the chorionic plate". Journal of Anatomy. 211 (6): 698–706. doi:10.1111/j.1469-7580.2007.00819.x. PMC 2375851. PMID 17973911.
External links
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