Neural Induction 1

Question 1

What tissues arise from dorsal ectoderm? Ventral ectoderm?

Answer 1

Dorsal: neural tissue
Ventral: epidermis

Question 2

What tissues arise from the mesoderm?

Answer 2

Muscle, most bones, (+notochord and somites).

Question 3

What tissues arise from the endoderm?

Answer 3

Gut tissues.

Question 4

How are the 3 germ layers established during gastrulation? Where does this process begin?

Answer 4

Involution, which begins at the dorsal lip and defines the dorsal-ventral axis.

Question 5

What was one of the earliest fate-mapping techniques?

Answer 5

Insertion of dyed agar chips into the Xenopus embryo.

Question 6

What simple experiment was used to define the conditions under which neural tissue was formed?

Answer 6

Spemann transplantation experiment. Moved ectoderm at early and late gastrula, observed that neural fate isn’t determined until interaction with the organizer (mesoderm).

Question 7

What does transplantation of the Spemann Organizer into another blastula trigger?

Answer 7

Development of a second neural tube and body axis (two-headed tadpoles!).

Question 8

How does the Spemann Organizer specify neural fate?

Answer 8

It produces noggin, a factor which inhibits BMP and induces neural tissue development.

Question 9

If you take presumptive epidermis and add a BMP inhibitor (ex: noggin) what happens?

Answer 9

The tissue dorsalizes and adopts a neural fate.

Question 10

What other region influences the Spemann organizer? What signalling pathway does it act through?

Answer 10

The Nieuwkoop centre activates the Spemann organizer via Wnt/beta-catenin signalling.