Lecture 14 - Vertebrate somite formation Flashcards
Do vertebrate also have segments?
- Yes
- Vertebrae and ribs are examples
Where do adult vertebrate segments come from?
Embryonic structures called SOMITES
What do somites form in a developed vertebrate?
- Vertebrae and ribs (sclerotome)
- Skeletal muscle (myotome)
- Dermis of back (dermotome)
How do somites form in relation to the node?
- They form at a given distance from it
- Therefore, the presomitic mesoderm maintains a constant length
How are segments formed in Vertebrates?
The somites buds off one at a time
What are the three features of somite formation? [3]
- Temporal (time)
- Spatial (distance)
- Physcial (shape)
What genes has been discovered to help in somite formation?
Genes relating to hairy
What are the Vertebrate Hairy genes?
- Homologues for the Drosophila pair-rule gene
- Expressed in presomitic mesoderm and somites
Why is Hairy expression
inconsistent between embryos?
- MAYBE Hairy expression is not tightly
regulated - MAYBE Hairy expression is dynamic
What is interesting about Hairy expression?
It is dynamic and changes rhythmically, with a 90 minute period
How is Hairy expression controlled?
Via Notch signalling
Why does Notch only activate Hairy every 90 minutes?
- Notch activates Hairy, and Hairy inhibits Notch
- This creates a cycle
What other genes are invovled in the Notch signalling? [5]
- Lunatic fringe
- Hes1
- Hey2
- Hes7
- Delta
What other genes are involved in Wnt signalling? [1]
- Axin2
What happens to somite formation i the inhibition of Notch signalling?
No somites are formed
