Chorionic villi

Chorionic villi
Diagram of a transverse section, showing the mode of formation of the amnion in the chick. The amniotic folds have nearly united in the middle line. Ectoderm, blue; mesoderm, red; entoderm and notochord, black. (Villi of chorion labeled at upper left.)
Model of human embryo 1.3 mm. long. (Villi of chorion labeled at lower right.)
Gray's	subject #12 60
Days	24
MeSH	Chorionic+Villi

Chorionic villi are villi that sprout from the chorion in order to give a maximum area of contact with the maternal blood.

Embryonic blood is carried to the villi by the branches of the umbilical arteries, and after circulating through the capillaries of the villi, is returned to the embryo by the umbilical veins.

Thus, the villi are part of the border between maternal and fetal blood during pregnancy.

In 1983 an italian biologist named Giuseppe Simoni discovered a new method of prenatal diagnosis using chorionic villi.

Development

The chorion undergoes rapid proliferation and forms numerous processes, the chorionic villi, which invade and destroy the uterine decidua and at the same time absorb from it nutritive materials for the growth of the embryo.

They undergo several stages, depending on their composition.

Stage	Description	Period of gestation	Contents
Primary	The chorionic villi are at first small and non-vascular.	End of 4th week	trophoblast only [1]
Secondary	The villi increase in size and ramify, while the mesoderm grows into them.	5th week	trophoblast and mesoderm[1]
Tertiary	Branches of the umbilical vessels grow into the mesoderm, and in this way the chorionic villi are vascularized.	5th - 6th week	trophoblast, mesoderm, and blood vessels [1]

Until about the end of the second month of pregnancy the villi cover the entire chorion, and are almost uniform in size, but after this they develop unequally.

Relations

The villi can also be classified by their relations:

Floating villi

These villi are found floating freely in the intervillous space. They exhibit a bi-layered epithelium consisting of cytotrophoblasts with overlaying syncytium (syncytiotrophoblast).

Anchoring (stem) villi

These villi act to stabilise mechanical integrity of the placental-maternal interface.

Tissue composition and cell types

The bulk of the villi consist of connective tissues in which blood vessels are found. Most of the cells in the connective tissue core of the villi are fibroblasts. Macrophages known as Hofbauer cells are also present.

Additional images

• 

  Section through the embryo.

• 

  Transverse section of a chorionic villus.

• 

  Primary chorionic villi. Diagrammatic.

• 

  Secondary (Tertiary? Vessels are present.) chorionic villi. Diagrammatic.

• 

  Human embryo of about fourteen days, with yolk-sac.

Stem cell

Chorionic villi are rich of stem cells: Biocell Center, a biotech company managed by Giuseppe Simoni and based also in Medford, MA, is studying and testing these types of stem cells. Chorionic stem cells, like amniotic stem cells, are multipotent stem cells without any ethical problem and now it's possible to criopreserve amniotic stem cell for autologous use ^[2][3][4].

See also

• Chorionic villus sampling
• Villitis of unknown etiology

References

1. ^ ^{a b c} Larsen, William J. : Human embryology. Sherman, Lawrence S.; Potter, S. Steven; Scott, William J. 3. ed.
2. ^ "European Biotech Company Biocell Center Opens First U.S. Facility for Preservation of Amniotic Stem Cells in Medford, Massachusetts | Reuters". 2009-10-22. http://www.reuters.com/article/pressRelease/idUS166682+22-Oct-2009+PRN20091022. Retrieved 2010-01-11. 
3. ^ "Europe's Biocell Center opens Medford office - Daily Business Update - The Boston Globe". 2009-10-22. http://www.boston.com/business/ticker/2009/10/europes_biocell.html. Retrieved 2010-01-11. 
4. ^ "The Ticker - BostonHerald.com". http://www.bostonherald.com/business/general/view/20091022the_ticker. Retrieved 2010-01-11. 

External links

• http://www.med.umich.edu/lrc/coursepages/M1/embryology/embryo/06placenta.htm

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.