Week 2 - Extra Lectures

Question 1

What are the neural crest derivatives?

Answer 1

“MOTEL PASS DC”

Melanocytes
Odontoblasts
Tracheal cartilage
Enterochromaffin cells
Laryngeal cartilage

Pseudouniplar cells
All ganglia/Adrenal medulla
Schwann cells
Spiral membrane

Dorsal root ganglia
Parafollicular C cells of thyroid

Question 2

Describe neural crest formation.

Answer 2

1. Neural crest cells dissociated from the neural tube and surface ectoderm
2. The cells then undergo an epithelial-mesenchymal transition
3. The neural crest cells then migrate to other areas:
   a. Trunk region (via the basal ganglia)
   b. Ventral pathway (via the anterior somite)
   c. Cranial end (via the anterior neuropore)

Question 3

Describe neural tube formation.

Answer 3

1. Gastrulation and formation of the primitive streak
   a. Epiblast cells migrate towards the primitive streak
   b. Epiblast cells detach from the epiblast
   c. The cells move beneath the epiblast, creating the endoderm and mesoderm
   i. This is via an invagination process, controlled by FGF8
   d. Remaining epiblast cells form the ectoderm
2. Notochord formation
   a. A tube extends from the primitive node
   b. This tube forms the axial process
   c. The axial process forms the notochordal process/plate
   d. This develops into the notochord
3. Formation of the neural plate
4. Process of neurulation
   a. Lengthening of the neural plate
   b. Elevation of the neural plate
   c. Fusion of the neural folds to form the neural tube

Question 4

Describe the process of spinal cord development.

You may also draw a diagram.

Answer 4

1. Neural tube consists of neuroepithelial cells (thick pseudostratified squamous epithelium)
2. Neuroepithelial cells give rise to neuroblasts (primitive nerve cells)
3. Neuroblasts form the mantle layer
   a. Mantle layer develops into grey matter
4. Nerve fibres projecting from the neuroblasts form the marginal layer
   a. Marginal layer develops into white matter
5. Neural tube walls begin to differentiate:
   a. Dorsal aspect thickens to form the alar plate
   i. This develops into the sensory neurons
   b. Ventral aspect thickens to form the basal plate
   i. This develops into the motor neurons
   c. Sulcus limitans (longitudinal groove) separates the alar and basal plates
   d. Dorsal median septum and ventral fissure form, as well as the dorsal/ventral horns
   i. NOTE: in thoracic/upper lumbar regions there will also be an intermediate horn

Question 5

List the 8 types of CNS drug.

Answer 5

1. Anaesthetics
2. Anxiolytics and sedatives
3. Antipsychotics
4. Antidepressants
5. Analgesics
6. Psychomotor stimulants
7. Psychomimetic drugs
8. Cognition enhancers