Gastrulation in mammals and chick II Flashcards
What does the epiblast produce following formation of the cavity?
Nodal precursor protein
What does nodal act on?
Extra embryonic ectoderm
What does nodal activate the expression of?
Furin and PCSK6
What are furin and PCSK6?
Convertase enzymes
What can furin and PCSK6 do?
Process nodal
What does nodal act on following processing?
Crypto
Role of crypto?
W/ GDF3 they specify the distal visceral endoderm
What is the distal visceral endoderm?
A signalling centre
Which genes can nodal repress?
Genes of the extra embryonic visceral endoderm, like Hnf4, Gata4
Which genes does nodal maintain expression of in the embryonic visceral endoderm?
FGF5, FGF8, Otx2, FoxA2
Role of FGF5 and FGF8?
Critical in commencement of gastrulation
Nodal effect in the epiblast?
Activates BMP4, which activates Wnt 3
What are Wnt3, FGF4 and FGF8 important for?
Specification of the posterior part of the embryo
Where does Wnt activate brachyury?
Junction region near the epiblast/extraembryonic endoderm region
What is brachyury upstream of?
FGF8
Roughly when does gastrulation start?
6.5 days of development
What happens at the initiation of gastrulation?
Activation of brachyury bc of Wnt signalling
What happens as a result of brachyury activation at the start of gastrulation?
Activation of FGF4 and 8
Result of activation of FGF4 and FGF8?
Epithelial mesenchymal transition of cells
Result of EMT of cells bc of FGF4 and 8?
Cells from the epiblast migrate towards the interior
How does FGF4 and 8 signalling lead to EMT?
Adherens junctions are lost, cells detach from basement membrane and they transition to mesenchyme state
Structure of the chick embryo?
Blastodisc–> flattened structure lying on top of the yolk
Cell migration path from the epiblast in a chick?
Migrate from the epiblast and pass through the primitive streak
What is the anterior part of the primitive streak called?
Node
