Chorion

Jump to navigation Jump to search
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

Template:Infobox Anatomy

WikiDoc Resources for Chorion

Articles

Most recent articles on Chorion

Most cited articles on Chorion

Review articles on Chorion

Articles on Chorion in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Chorion

Images of Chorion

Photos of Chorion

Podcasts & MP3s on Chorion

Videos on Chorion

Evidence Based Medicine

Cochrane Collaboration on Chorion

Bandolier on Chorion

TRIP on Chorion

Clinical Trials

Ongoing Trials on Chorion at Clinical Trials.gov

Trial results on Chorion

Clinical Trials on Chorion at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Chorion

NICE Guidance on Chorion

NHS PRODIGY Guidance

FDA on Chorion

CDC on Chorion

Books

Books on Chorion

News

Chorion in the news

Be alerted to news on Chorion

News trends on Chorion

Commentary

Blogs on Chorion

Definitions

Definitions of Chorion

Patient Resources / Community

Patient resources on Chorion

Discussion groups on Chorion

Patient Handouts on Chorion

Directions to Hospitals Treating Chorion

Risk calculators and risk factors for Chorion

Healthcare Provider Resources

Symptoms of Chorion

Causes & Risk Factors for Chorion

Diagnostic studies for Chorion

Treatment of Chorion

Continuing Medical Education (CME)

CME Programs on Chorion

International

Chorion en Espanol

Chorion en Francais

Business

Chorion in the Marketplace

Patents on Chorion

Experimental / Informatics

List of terms related to Chorion

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


The chorion surrounds the embryo and other membranes. It consists of two layers: an outer formed by the primitive ectoderm or trophoblast, and an inner by the somatic mesoderm; with this latter the amnion is in contact.

The trophoblast is made up of an internal layer of cubical or prismatic cells, the cytotrophoblast or layer of Langhans, and an external layer of richly nucleated protoplasm devoid of cell boundaries, the syncytiotrophoblast.

It 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.

The chorionic villi are at first small and non-vascular, and consist of trophoblast only, but they increase in size and ramify, while the mesoderm, carrying branches of the umbilical vessels, grows into them, and in this way they are vascularized.

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. 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.

The greater part of the chorion is in contact with the decidua capsularis, and over this portion the villi, with their contained vessels, undergo atrophy, so that by the fourth month scarcely a trace of them is left, and hence this part of the chorion becomes smooth, and is named the chorion læve; as it takes no share in the formation of the placenta, it is also named the non-placental part of the chorion.

On the other hand, the villi on that part of the chorion which is in contact with the decidua placentalis increase greatly in size and complexity, and hence this part is named the chorion frondosum.

Additional images

See also

External links

Template:Gray's

Template:Embryology

de:Chorion sr:Хорион


Template:WS