Lecture 9 - Gastrulation Flashcards
What is Gastrulation?
The coordinated cell movements to re-organise the blastula into a trilaminar structure
What is gastrulation initaiated by?
The formation of bottle cells
Where do bottle cells form?
- At the border of mesoderm and ectoderm
- At the dorsal side of the embryo
How do battle cells change shape to initiate gastrulation?
They get longer and concave
What types of tissue movements occur during gasturlation? [4]
- Involution
- Convergent extension of mesoderm
- Radial intercalation of deep layer of ectoderm
- Eipboly of superficial layer of ectoderm
What is involution?
The rolling in of the endoderm and mesoderm
Where is fibronectin secreted from?
From cells of the blastocoel roof
What is the role of fibronectin?
- Forms an extracellular matrix
- Mesoderm cells express integrins that bind to fibronectin
How is gastrulation in chick embryos performed?
- Cells invaginate from the epiblast through the primitive streak
- They form the definitive endoderm
What happens to mesoderm cells around the primitive streak?
They ingress through it
How is invagination initiated in sea urchin embryos?
Change in shape of some cell causes invagination of endoderm
- Caused by contractile filaments on the outer edge of cells
What does gut arrangement in a sea urchin embryo require?
- Rearrangement within the endoderm
- Convergent extension
