Axis Specification Other Vertebrates - Final

Question 1

What is the equivalent of the organizer, and Nieuwkoop Center, in fish and chicks?

Answer 1

Organizer: shield and Henson’s node

Nieuwkoop Center: Bozozok, Koller’s sickle.

Question 2

What is required with half baked?

Answer 2

It is an E cadherin that is involved in successful epiblast formation.

Question 3

What is PCP required for in zebrafish?

Answer 3

Required for mesodermal convergent extension similar to amphibians. Wnt11 mutants do not have directed migration in this instance.

Question 4

Spatially, what 4 molecules exist in zebrafish?

Answer 4

Oxt2 exists in the brain, FGF,Wnt, and RA in the posterior.

Question 5

In chick embryos, where do definitive endoderm, and hypoblast cells come from?

Answer 5

Definitive endoderm is made from epiblast cells that invade the hypoblast. Hypoblast cells arise from both the posterior marginal zone, and epiblast ingression.

Question 6

In chicks, how are the primitive streak, Henson’s node, and the notochord related?

Answer 6

The mesodermal tissue ingresses through the primitive streak, and at the top of the primitive streak is Henson’s node, which some tissue moves through anteriorly to become the notochord. As Henson’s node regresses, the notochord is made.