Embryology question

[virtualmaster999]

Hi everyone!

Could someone help clarify this for me (and if im getting this right)?

-So in humans, there's the zona pellucida, and in sea urchins, theres the vitelline.
-The cortical rxn involves cortical granules, leading to slow block in polyspermy for the egg (vitelline hardens into fert. membrane)
-The acrosomal rxn involves the acrosome releasing its contents to the egg, and the acrosome is involved in the fast block to polyspermy

Now here's where im getting stuck: is the cortical rxn exclusive to the sea urchin (since it's the vitelline that forms the fertilization membrane)...or does this happen in humans too?

Main question here: Does the cortical/ acrosome rxn occur in both humans/ sea urchin?

Id really appreciate the help! Thanks in advance!!

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[strep mutans]

For the purpose of the DAT, just remember that the zona pellucida is the vitelline layer of mammals.

It has been assumed that both fast and slow blocks occur with the zona pellucida, although the exact mechanisms vary among species due to protein variation.

Apparently new research is questioning the idea of fast and slow blocks in human fertilization, though. See here:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463667/

I wouldn't worry about getting a question asking if fast/slow blocks occur in humans specifically. Rather, you should know what is happening in fast vs slow, the purpose, and be able to identify zona pellucida = mammals. Also, realize that the vitelline layer / zona pellucida is an example of a glycocalyx in eukaryotes.

Hope that helps!

 

[virtualmaster999]

For the purpose of the DAT, just remember that the zona pellucida is the vitelline layer of mammals.

It has been assumed that both fast and slow blocks occur with the zona pellucida, although the exact mechanisms vary among species due to protein variation.

Apparently new research is questioning the idea of fast and slow blocks in human fertilization, though. See here:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463667/

I wouldn't worry about getting a question asking if fast/slow blocks occur in humans specifically. Rather, you should know what is happening in fast vs slow, the purpose, and be able to identify zona pellucida = mammals. Also, realize that the vitelline layer / zona pellucida is an example of a glycocalyx in eukaryotes.

Hope that helps!

Thanks, much appreciated!

 

[510586]

Hi everyone!

Could someone help clarify this for me (and if im getting this right)?

-So in humans, there's the zona pellucida, and in sea urchins, theres the vitelline.
-The cortical rxn involves cortical granules, leading to slow block in polyspermy for the egg (vitelline hardens into fert. membrane)
-The acrosomal rxn involves the acrosome releasing its contents to the egg, and the acrosome is involved in the fast block to polyspermy

Now here's where im getting stuck: is the cortical rxn exclusive to the sea urchin (since it's the vitelline that forms the fertilization membrane)...or does this happen in humans too?

Main question here: Does the cortical/ acrosome rxn occur in both humans/ sea urchin?

Id really appreciate the help! Thanks in advance!!

Also we should know that the fast block is due to depolarization right? And how the fast block stimulates the slow block

 

[ywcywc]

Campbell (8th edition) says that mammals usually do not have fast block. ( I remember but I have not make sure it).