Development of the CNS

Question 1

What is the wall of the neural tube? What does this develop into?

Answer 1

the neuroepithelium. The cells of the CNS

Question 2

What do the cells of the PNS develop from?

Answer 2

the neural crest

Question 3

Diagram to show embryonic CNS development. Label.

Answer 3

Question 4

What does the neuroepithelium differentiate into, and what are the tissues’ functions?

Answer 4

•Neuroblasts

All neurons with cell bodies in the CNS

•Glioblasts

Astrocytes, oligodendrocytes

•Ependymal cells

Lining ventricles and central canal

Question 5

What do neural crest cells differentiate into?

Answer 5

• Sensory neurons of dorsal root ganglia
• Postganglionic autonomic neurons
• Schwann cells
• Non-neuronal derivatives e.g. melanocytes

Question 6

Describe the proliferation of cells in the neural tube during embryonic growth.

Answer 6

Rapid from outside to inside neural tube.

Question 7

Label diagram to show layers of neuroepithelium.

Answer 7

Question 8

Label diagram to show layers of the neural tube.

Answer 8

Question 9

Outline 3 ways CNS differentiation occurs.

Answer 9

1. signalling molecules, secreted by surrounding tissues, interact with neuroblasts and receptors.
2. Control migration + axonal growth by attraction and repulsion.
3. Depends on concentration gradient + timing.

Question 10

What parts of neural tube develop into what types of cell?

Answer 10

Ventral (basal plate) - motorneurons and interneurons

Dorsal (alar plate) - interneurons

Neural crest cells - sensory neurons in dorsal root ganglion.

Question 11

Compare mature and immature spinal cord. Label diagram.

Components - dorsal horn, root, root ganglion.

ventral root, horn.

White matter

Central canal

Answer 11

Question 12

Brainstem. Label diagram.

Answer 12

Question 13

Label brain at 4 weeks. 4 components.

Answer 13

Question 14

Label developing brain at 5 weeks.

Answer 14

Question 15

Label brain at 8 weeks, including ventricles.

What new feature arises?

Answer 15

cerebral aqueduct.

Question 16

Name the flexures of the 4 week old developing brain (dorsal to ventral)

Answer 16

1. cephalic flexure
2. pontine flexure
3. cervical flexure

Question 17

Label diagrams of the developing cortex.

What components aids development + extension.

Answer 17

Radial glial cell

Question 18

How might developmental disorders arise?

Answer 18

• Normal development depends on the coordinated completion of several complex processes (e.g. proliferation, differentiation, migration, axon growth and synapse formation)
• Genetic mutation and environmental factors such as the mother’s lifestyle, diet and teratogens can interfere with these processes

Question 19

Outline 4 non spinal cord neural tube defects.

Answer 19

1. craniorachischisis - open brain and spinal cord
2. anencephaly - open brain + lack of skull vault
3. encephalocele - herniation of meninges + brain
4. iniencephaly - extreme retroflexion of head

Question 20

Outline 4 spinal cord developmental defects.

Answer 20

1. spinal bifida occulta - closed asymptomatic NTD. some vertebrae not closed.
2. closed spinal dysraphism - deficiency of at least to vertebral arches.
3. meningocele - protusion of meninges (filled with CSF)
4. myelomeningocele - open spinal cord (with meningeal cyst)