Diff7 - 22 Flashcards
Where is the Spemann organiser?
Mesoderm
Where is the Nieuwkopp centre?
Endoderm
Outline the endoermal signal pathway
Veg1/VgT > nodal/beta-catenin > nieukoop > spemann organiser
How is the mesoderm subdivided?
BMP/BMP-antagonistic signals
What are the epaxial muscles?
Deep back muscles
What are the hypaxial muscles?
Limb, body wall and abdominal
What does the ventral somite become?
Epithelia/mesenchymal; sclerotome > cartilage and bones
What does dorsal somite become?
Epithelia/demomyotome; medial myotome; dermatome
What does the dermomyotome become?
Hypaxial muscles innervated by ventral rami
What does the medial myotome become?
Epaxial muscles innervated by dorsal rami
What does the dermatome become?
Dermis
How many vertebrae are humans born with?
33
How many vertebrae do adult humans have?
24 (9 fuse)
How many somites do humans have as embryos?
33
How many somites do chicks have?
55
How many somites do mice have?
65
What does paraxial mesoderm specification require?
BMP anatagonists
How fast are somites formed in chicks?
Every 90 minutes
How are somites formed?
Budding off the pre-somitic mesoderm
What must cells within the pre-somitic mesoderm respond to?
Positional information, left/right co-ordination, anterior/posterior boundary info, cleft formation
How are boundaries created in somite formation?
Boundary cells instruct cells that are anterior to form a boundary - via notch expression
What condition in humans is caused by absence of Notch signalling?
Jarcho Lewin syndrome - spondylocostal dysplasia (ossification centres do no align)
