Embrio 1.2: Second Week

Question 1

Where do cells of the amnios come from? Clinical relevance

Answer 1

All cells come from the bouton embryonaire

If there is a genetic malformation in the amnios cells, we know it must be related to the bouton embryonaire and not the trophoblast for example.

Question 2

What is the first few things that happen in periode des deux?

Answer 2

Bouton Embryonaire gives us Epiblast and Hypoblast
It also creates **Cavité amniotique **
Finally, continued proliferation of the Cytotro phoblastes to give more Syncytiotrophoblaste

Question 3

What is the main difference between day 8 and 10?

Answer 3

les cellules du cyto-trophoblaste ont proliféré, et leur migration interne génère le mésoderme (or mesenchyme they are synonyms) extra-embryonnaire. Ces cellules de mésodreme extra-embryonnaire génèrent la membrane de Heuser.

Donc, mesenchyme et membrane de heuser come from cytotrophoblaste

Question 4

True or False,

Syncytiotrophoblaste proliferation is key for going from day 7 to 8.

Answer 4

FALSE,

Syncytiotrophoblaste does not proliferate anymore. Only cytotrophoblaste roliferates which grows the Syncytiotrophoblaste

cytotrophoblaste proliferating outside will produce more Syncytiotrophoblaste
cytotrophoblaste proliferating inside will give mesenchyme extra-embryonnaire + membrane heuser

Question 5

Large difference between day 10 and 11?

Answer 5

Syncytiotrophoblaste entourne tout l’emryo.

More lacunes and more vaisseau maternel

Question 6

Large difference between day 11 and 13?

Answer 6

Le mesynchyme extrerne will cover all of the embryo

Question 7

What is Vésicule vitelline?

Answer 7

It is the cavity that is created between Hypoblaste and Membrane de Heuser

This is the old blastocoel

Question 8

Day 14 what happens?

Answer 8

Coelome extra-embryonnaire grow and push into the Membrane de Heuser creating 2 cavities
1 Vésicule vitelline primitive (below) will disapear and so we only have vésicule vieline secondaire

Question 9

Day 15 what happens?

Answer 9

Coelome extra-embryonnaire will grow enough to separate the embryo from the inner Cytottophoblasie

The only way of contanct between the embryo and the Cytottophoblasieis the pédicule embryonnaire.

pédicule embryonnaire is key as it it via this passage that the vessicule will be able to penetrate to feed the baby

Question 9

What prevents ectoblast formation and what is this?

Answer 9

The Epiblast can transform itself into the Ectoblast

This is inhibited by the contanct of epiblast to the hypoblast. When eventually the mesenchyme separates these two thats when the inhibition is gone and Epiblast transforms into ectoblast

Ectoblast is responsible for the formation of the Ligne primitive