Development of the Nervous System

Question 1

From which layer of the trilaminar disc is the nervous system derived?

Answer 1

Ectoderm

Question 2

Describe the formation and function of the notochord

Answer 2

Pre-notochordal cells migrate through the primitive streak and form a solid rod of cells in the midline

The notochord causes side-specific signalling and triggers neuralation

Question 3

Describe the process of neuralation

Answer 3

The cells of the notochord signal the overlying ectoderm to multiply and thicken.
The neural plate thickens to such an extent that the edges elevate and curl towards each other to meet in the midline. This creates the neural tube

Question 4

At each end of the neural tube, there is an opening called a neuropore. When do the neuropores close?

Answer 4

Anterior neuropore closes at day 24

Posterior neuropore closes at day 26

Question 5

Describe the formation of the primary brain vesicles

Answer 5

The cranial end of the neural tube expands in to 3 areas of dilation: prosencephalon, mesencephalon and rhomboencephalon

Question 6

The primary brain vesicles re-organise in to 5 secondary brain vesicles. What does the forebrain (prosencephalon) organise in to?

What will they structures become?

Answer 6

Telecephalon - cerebral hemispheres

Diencephalon - thalamus

Question 7

The primary brain vesicles re-organise in to 5 secondary brain vesicles. What does the midbrain (mesencephalon) organise in to?

What will they structures become?

Answer 7

Remains mesencephalon and will become the midbrain

Question 8

The primary brain vesicles re-organise in to 5 secondary brain vesicles. What does the hindbrain (rhomboencephalon) organise in to?

What will they structures become?

Answer 8

Metencephalon - pons and cerebellum

Myelencephalon - medulla oblongata