Development of the Nervous System

Question 1

What induces neurulation?

Answer 1

Notochord

Question 2

What is neurulation?

Answer 2

Formation of the neural tube from the ectoderm, following gastrulation

Question 3

What is the neural plate?

Answer 3

Thickening of neuroectoderm

Question 4

As the lateral edges of the neural plate elevate, what is the depressed mid-region called?

Answer 4

Neural groove

Question 5

How do the neural folds create the neural tube?

Answer 5

Approach each other in the midline and fuse to produce the neural tube

Question 6

What do neural tube defects result from?

Answer 6

Failure of the neural tube to close which can occur caudally or cranially

Question 7

What does a cranial neural tube defect result in?

Answer 7

Anencephaly

Question 8

What does a caudal neural tube defect result in?

Answer 8

Spina bifida

Question 9

What is hydrocephalus?

Answer 9

An accumulation of CSF within the brain

Question 10

What is rachischisis?

Answer 10

Result of failure of neural fold elevation, no neural tube formed

Question 11

How can NT defects be diagnosed and prevented?

Answer 11

USS, raised maternal serum a-fetoprotein (embryonic proteins lead into amniotic fluid in open defects)

Folic acid given pre-conceptually and for the first trimester reduces incidence by 70%

Question 12

What does the prosencephalon become?

Answer 12

Forebrain

Question 13

What does the mesencephalon become?

Answer 13

Midbrain

Question 14

What does the rhombencephalon become?

Answer 14

Hindbrain

Question 15

At 5 weeks of development, five secondary brain vesicles are formed. What are these?

Answer 15

Telencephalon, diencephalon (forebrain)
Mesencephalon (midbrain)
Metencephalon, myelencephalon (hindbrain)

Question 16

What is the mature derivative of the telencephalon?

Answer 16

Cerebral hemispheres

Question 17

What is the mature derivative of the diencephalon?

Answer 17

Thalamus

Question 18

What is the mature derivative of the mesencephalon?

Answer 18

Midbrain

Question 19

What is the mature derivative of the metencephalon?

Answer 19

Pons, cerebellum

Question 20

What is the mature derivative of the myelencephalon?

Answer 20

Medulla oblongata

Question 21

Is the alar plate sensory or motor?

Answer 21

Sensory (dorsal)

Question 22

Is the basal plate sensory or motor?

Answer 22

Motor (ventral)

Question 23

What are neural crest cells?

Answer 23

Cells of the lateral border of the neuroectoderm tube that become displaced and enter the mesoderm and undergo epithelial to mesenchymal transition

Question 24

Give some examples of neural crest derivatives

Answer 24

Schwann cells, glial cells, odontoblasts, C cells of thyroid gland, melanocytes, adrenal medulla

Question 25

What is Hirschsprung’s disease?

Answer 25

No enteric ganglia - aganglionic megacolon

Blockage, faeces stuck in bowels