Germ Layer Formation Flashcards
Which cells contribute to the embryo in the morula?
The top cells
In the xenopus the top and bottom part of the morula are referred to as what?
Top = animal Bottom = vegetal
In chicks the top and bottom parts of the morula are referred to as what?
Epiblast = top Hypoblas = bottom`
How do the vegetal and animal cells develop so they are different from each other?
Some cytoplasmic components are only at the bottom of the egg cell ie the cytoplasm is not uniform or symetric
Their are particular components in yhe vegetal hemisphere which polarise the cell
The first division of the oocyte is in which plane?
Horizontal
Master transcription factors can upregulate up to how many genes?
20,000
As cell division continues, changes in osmolarity leads to what?
The formation of the blastoceol
What is the blastoceol?
A hollow ball of cells
How is blastoceol formation different in chicks and humans?
The embryo is flattened and is often represented as two thin sheets
Which transcription factor is expressed in the vegetal pole?
VgT
VgT upregulates which important gene?
Nodal
What is nodal?
A morphogen
Where does nodal diffuse to?
The animal hemisphere cells - these cells have receptors for nodal
Nodal determines cell fate according the concentration the cell is exposed to. Cells with high, medium and low amounts of nodal become what?
High = endoderm Middle = mesoderm Low = ectoderm
Where is Vgt and Nodal expressed in chicks and humans?
In the hypoblast
