What is the role of ephrin and ephrin receptor in

7. What is the role of ephrin and ephrin receptor in somite formation?
8. Describe the process of somite epithelization. What are the roles of fibronectin
and N-cadherin?

9. Do somites continue to exist in the body, or are they only temporary present in
the embryo?
10. Somites first subdivide into sclerotome, dermatome and myotome. What
signals are involved in these subdivisions and where are they coming from?
11. Which cells (derivatives of what) are forming an anterior part of each of the
vertebra (cartilages, and then bones)? Which cells are forming a posterior part of
each of the vertebra? Why does this happen?