Lecture 2-NS Development

Question 1

Which process produces the notochord?

Answer 1

Gastrulation

Question 2

What does the notochord induce?

Answer 2

Neurulation -> neural plate

Question 3

What is the depressed mid-region of the neural plate called?

Answer 3

Neural groove

Question 4

How is the neural tube formed?

Answer 4

Neural folds approach each other in the midline and fuse

Question 5

What is the notochord?

Answer 5

Solid rod of cells running in the midline which directs the conversion of overlying ectoderm to neurectoderm

Question 6

What is anencephaly?

Answer 6

Anterior neuropore doesn’t close -> no brain

Question 7

What is spina bifida?

Answer 7

Posterior neuropore defect

Question 8

Where does spina bifida most commonly occur?

Answer 8

In lumbosacral region

Question 9

What are the two forms of spina bifida?

Answer 9

• meningocoele: only meninges herniate, hydrocephalus
• myelomeningocoele: meninges, bone and parts of cord herniate + hydrocephalus -> neurological deficit due to neuronal tissue in cyst

Question 10

What is rachischisis?

Answer 10

Failure of neural fold elevation -> splayed nervous tissue across the surface of the embryonic back

Question 11

How are NTDs diagnosed?

Answer 11

• raised maternal serum alpha fetoprotein

- USS

Question 12

How can NTDs be prevented?

Answer 12

Folic acid

Question 13

Describe how the cauda equina forms

Answer 13

• Neural tube gives rise to spinal cord
• at 3rd month, spinal cord is same length as vertebral column but after, vertebral column grows after
• spinal roots must elongate because they exit at intervertebral foramen -> cauda equina

Question 14

What are the three primary brain regions formed during neurological fold formation?

Answer 14

• forebrain = prosencephalon
• midbrain = mesencephalon
• hindbrain = rhombencephalon

Question 15

Which secondary brain vesicles form from the prosencephalon and what are their derivatives?

Answer 15

• telencephalon -> cerebral hemispheres

- diencephalon -> thalamus

Question 16

Which secondary brain vesicles form from the mesencephalon and what are their derivatives?

Answer 16

Mesencephalon -> midbrain

Question 17

Which secondary brain vesicles form from the rhombencephalon and what are their derivatives?

Answer 17

• mesencephalon -> pons, cerebellum

- myelencephalon -> medulla oblongata

Question 18

What are flexures?

Answer 18

When neural tube folds up as it runs out of space to grow

Question 19

Where is the cervical flexure?

Answer 19

Spinal cord - hindbrain junction

Question 20

Where is the cephalic fixture?

Answer 20

Midbrain region

Question 21

What is the role of the ventricular system?

Answer 21

To cushion the brain and spinal cord within their bony cases

Question 22

How can spina bifida be treated?

Answer 22

Shunting fluid into abdominal cavity

Question 23

Describe the organisation of the neural tube from the inside out

Answer 23

• neuroepithelial layer
• intermediate (mantle) layer: neuroblasts
• marginal layer: processes

Question 24

True or false: the alar plate is responsible for motor function

Answer 24

FALSE - sensory (basal is motor)

Question 25

What is the neural crest and what happens to it?

Answer 25

• cells of the lateral border of the neurectoderm tube

- becomes displaced and enters the mesoderm and undergoes epithelial to mesenchymal transition

Question 26

What is Hirschprung’s disease?

Answer 26

Aganglionic megacolon due to abnormal neural crest cell migration

Question 27

What is DiGeorge syndrome?

Answer 27

Abnormal neural crest cell migration -> thyroid deficiency, immunodeficiency due to thymus defect, cardiac defect