Neural crest induction

Question 1

Neural crest cells have many derivatives. Give 4 examples.

Answer 1

1. Neurones
2. Cartilage and bone
3. Connective tissue
4. Melanocytes

Question 2

The neural crest cells only give rise to ectoderm. True or false?

Answer 2

False - they give rise to tissues from all 3 germ layers due to their extensive migratory ability.

Question 3

All facial nerves plus the teeth are derived from the neural crest. True or false?

Answer 3

True.

Question 4

All the cranial nerves are derived from neural crest cells. True or false?

Answer 4

False - the cranial nerves are a mixture of NC cells and mesodermal derivatives.

Question 5

The migratory patterns of NC cells are extensive. Tissues form when masses of migrating NC cells come together. True or false?

Answer 5

True.

Question 6

Why does a cleft lip form?

Answer 6

2 masses of NC cells do not fuse properly together after migration.

Question 7

Where do the NC cells originate from?

Answer 7

Before neurulation neural plate is flanked by neural crest cells and epidermal cells. During neurulation the neural plate forms the neural tube, and the epidermal cells form the overlying ectoderm. It is at this point that the NC cells delaminate to form the neural crest cell mass.

Question 8

What is the nose formed from?

Answer 8

2 masses of NC cells from the dorsal portion of the brain that migrate forwards and collide.

Question 9

The derivatives of NC cells become highly specialised and are not interchangeable between tissues. True or false?

Answer 9

True.

Question 10

All NC cells are born in the dorsal portion of the embryo and migrate anteriorly. True or false?

Answer 10

True, they all begin in the neural plate.

Question 11

What is at the a) anterior and b) posterior ends of the neural tube?

Answer 11

a) The brain

b) The spinal column

Question 12

Neural plate forms when BMP4 is suppressed by what?

Answer 12

Chordin and Noggin.

Question 13

When BMP4 is not suppressed, what does it form?

Answer 13

Epidermis.

Question 14

What is the name of the compound formed when chordin and noggin directly bind to BMP4?

Answer 14

anti-BMP

Question 15

A morphogen gradient of chordin and noggin is established. Describe this gradient.

Answer 15

High levels of chordin and noggin on the dorsal side, less/none on the ventral side of the embryo.

Question 16

What is the purpose of this chordin/noggin morphogen gradient?

Answer 16

Ensures anti-BMP forms on the dorsal side to allow neural plate to form, prevents the formation of anti-BMP on the ventral side so epidermis can form.

Question 17

What cell type does the following form:

a) high BMP
b) intermediate BMP
c) low BMP

Answer 17

a) epidermis
b) NC cells
c) neural plate

Question 18

Each cell type has a different threshold value of BMP. Changing the levels of BMP in different areas can thus result in ectopic tissues. True or false?

Answer 18

True.

Question 19

What would happen in lower than normal levels of BMP?

Answer 19

There would be no epidermis or NC cells, but the neural plate would form and expand towards the ventral side of the embryo.

Question 20

Do the threshold levels for each tissue change in relation to the BMP gradient?

Answer 20

No, they are fixed.

Question 21

What other gene families contribute to NC specification?

Answer 21

Wnt and FGF.