Nervous System Development I: Neurulation

Question 1

What happens in the 3rd Week?

Answer 1

• The Notochord releases chemicals to the overlying Ectoderm causing it to thicken and proliferate.
• This leads to the formation of the Neural Plate.

Question 2

Explain the Formation of the Neural Tube from the Neural Plate?

Answer 2

1)Longitudinal fissure occurs in the Longitudinal Plane of the Neural Plate.

2) Leads to depression of the Middle and lifting of the edges of the Neural plate causing the formation of:
- Neural Groove and Neural Folds.

3) These Neural Folds fuse together to form the “Neural Canal” - The Neural Canal can communicate freely with the Amniotic Cavity.

4)The Cranial opening of the Neural Canal is called “Rostral Neuropore” closes on the 25th day.
The Caudal opening of the Neural Canal is called the “Caudal Neuropore” will close on the 27th day.

This closing of both ends creates the Neural Tube.

Question 3

How do the Neural Crest Cells form?

Answer 3

They are formed from some cells which split from the Neural Tube.

Question 4

Which Systems are formed by the Neural Tube and the Neural Crest cells?

Answer 4

Neural Tube forms the CNS.

Neural Crest Cells form the PNS and ANS.

Question 5

What does each part of the Neural Tube form in the CNS?

Answer 5

The walls of the Tube will form the Brain and the Spinal Cord.

The Neural Canal will form the Ventricular System and the Central Canal.