Bio Question on Extraembryonic membranes

[Troyvdg]

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1. The membrane that functions in respiration in the embryo is the

a. amnion
b. allantois *ANSWER
c. chorion
d. umbilical chord
e. yolk sac

I'm a little confused by this, because the explanation states that the answer is the allantois because it enables the shell of the egg in birds and reptiles to exchange gases..I thought gas exchange was performed by the chorion in the eggs of birds/reptiles and later in development the allantois began to help with gas exchange. For human embryo's I understand how this would be right since it gives rise to the umbilical cord, but that doesn't match up to their explanation

 

[FeralisExtremum]

I think this is just a poorly designed question, I assume from Kaplan. I looked at three different bio sources, all three of them described the allantois and the chorion having a role in the diffusion of respiratory gases; only Kaplan emphasizes that the allantois is "involved with respiration...contains numerous vessels to transport O2, CO2, etc".

I definitely wouldn't try to look at it from the perspective of what they end up developing into and how those function in respiration, because that's extending past what the question is really asking you (not to mention it's complicated by the fact that the allantois and the chorion basically fuse as development progresses, and both give rise to parts of the placenta).

EDIT: Also checked Campbell's, which vaguely said "gas exchange" for the chorion function versus transport of oxygen to the embryo and getting rid of CO2 for the allantois.

EDIT 2: I believe the confusion may be that the chorion (being the outermost of the extraembryonic memberanes) permits gas exchange, but does not necessarily function directly in gas exchange like the allantois does.

 

[NhuPT]

Found this online, hope it helps:

Allantois: The allantois develops an extensive circulatory system connected to that of the embryo and driven by the new embryonic heart. When the allantois is fully developed it completely surrounds the embryo. This membrane has a number of functions:
1. Respiratory – the developing embryo uses oxygen and produces carbon dioxide i.e. it has respiration. It is unable to carry out this function for itself and hence the allantois oxygenates the blood and eliminates carbon dioxide.
2. Excretory – it removes the wastes that result from the embryo’s metabolism and deposits it in the allantoic cavity.
3. Digestive – it provides the means for the embryo to access the albumen and the calcium of the shell.

http://www.poultryhub.org/physiology/body-systems/embryology-of-the-chicken/

 

[412smb412]

respiration is gas exchange. in the human it actually occurs in the placenta not the umbilical cord. the umbilical cord is the connection btwn the mother and embyro but the blood never mixes. for example where does gas exchange occur in the human: its the alveoli NOT the lungs...

in reptiles and birds it occurs in the allantios which later is fused to chorion and thats why you will see both. however, i would stick with allantois...

 

[DAT-TAKER]

Related to this question, i would like to know what is the chorion and allantois derived from?

 

[hashtagpredental]

Related to this question, i would like to know what is the chorion and allantois derived from?

I believe both the chorion and amnion come from the trophoblast, which is the outermost cell layer of the blastocyst during embryonic development.

 

[DAT-TAKER]

I believe both the chorion and amnion come from the trophoblast, which is the outermost cell layer of the blastocyst during embryonic development.

Thanks you so much for letting me know.