Structure of the placenta, with a placental cotyledon marked in rectangle.
In human development, the cotyledons are the approximately 15-25 separations of the decidua basalis of the placenta, separated by placental septa. Each cotyledon consists of a main stem of a chorionic villus as well as its branches and subbranches etc.
The cotyledons receive fetal blood from chorionic vessels, which branch off cotyledon vessels into the cotyledons, which, in turn, branch into capillaries. The cotyledons are surrounded by maternal blood, which can exchange oxygen and nutrients with the fetal blood in the capillaries.
- 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.