Go Back   Freethought Forum > The Library > Articles & Essays > Science

Article Tools Display Modes
An Introduction to Zoology:  Chapter 6
An Introduction to Zoology: Chapter 6
Published by The Lone Ranger
Default The Chorion

The Chorion:
The chorion is the outermost of the four extraembryonic membranes, and its primary role is in gas exchange. You can easily find the chorion in a chicken egg; itís the thin membrane that lies just under the shell.

In amniotes that lay eggs, oxygen diffuses into the egg across the amnion as carbon dioxide diffuses across it in the opposite direction and to the outside. As the embryo inside the egg grows and its oxygen demands increase, the chorion partially fuses with the allantois to form the chorioallantoic membrane. The chorioallantoic membrane has a rich supply of blood vessels, allowing for rapid exchange of oxygen and CO2 between the embryo and the outside environment.

In placental mammals, extensions of the chorion known as chorionic villi penetrate into the lining of the motherís uterus. This brings embryonic and maternal blood vessels into close proximity, allowing for efficient exchange of nutrients and gases between the mother and the developing embryo.


Article Tools

Featured Articles
<<  <    Next Page: The Amnion (Page 20 of 24)    >  >>
By monruw on 03-30-2011, 01:55 PM
Default Re: An Introduction to Zoology: Chapter 6

why it's called animal-vegetal axis? sound like kinda food, meat and vegetable or what else~ any story behind this?
Reply With Quote
By The Lone Ranger on 05-22-2011, 01:35 AM
Default Re: An Introduction to Zoology: Chapter 6

"Vegetal," is related to "vegetable." Many plants can reproduce asexually, whereas virtually all animals reproduce sexually.

Probably for this reason, "vegetal" came to refer to processes in living things that are "plant-like," especially processes that do not occur through sexual reproduction. More to the point, perhaps, plants generally grow much more slowly than do animals. So the "vegetal" pole of an egg gets its name for the fact that the cells in this region grow and divide much more slowly than do the cells in the "animal" pole.


Reply With Quote

  Freethought Forum > The Library > Articles & Essays > Science

Currently Active Users Viewing This Article: 1 (0 members and 1 guests)
Article Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 09:35 AM.

Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

Article powered by GARS 2.1.8m ©2005-2006
Page generated in 0.37516 seconds with 14 queries