Development of the Nervous System

Question 1

Describe the embryonic origin of the entire nervous system

Answer 1

Tube of ectoderm

- 1 cell > 2 cells > 4 Cells > 16 cells > Morula >Blastocyst (implantation at week 1)

Question 2

Neural Plate

Answer 2

Formed as the mesoderm is forming and the overlying ectoderm starts to thicken

Eventually the neural plate starts to fold on itself creating neural folds and a neural groove

Question 3

Neural tube

Answer 3

Formed at week three as the neural folds fuse dorsally, it then separates from the ectoderm and becomes enclosed within the body and eventually becomes the CNS

Question 4

Neural Crest Cells

Answer 4

• Cells from each neural fold as the neural tube separates from the ectoderm
  
  • develop into Ganglia and Glial cells of the PNS

Question 5

Describe the Intermediate Zone

Answer 5

• Becomes gray matter in the spinal cord or white matter in the brain structures
• Oldest cells

Question 6

Cortical Zone

Answer 6

• Become inner brain gray matter

* No cortical plate/zone in the spinal cord

Question 7

Marginal Zone

Answer 7

-Becomes white matter in the spinal cord or outer cortex of the brain

Question 8

Alar Plate

Answer 8

Sensory (dorsal horn) endings of afferent cells

-Sensory cranial nerve nuclei

Question 9

Basal Plate

Answer 9

Motor (ventral horn) endings of efferent cells

-Motor cranial nerve nuclei

Question 10

Sulcus Limitans

Answer 10

-Week 4 - divides CNS into a dorsal and ventral component

Question 11

Name the three primary bulges

Answer 11

• Prosencephalon: anterior swelling - becomes forebrain
• Mesencephalon: middle swelling - becomes midbrain
• Rhombencephalon: posterior swelling - becomes hindbrain

Question 12

Name the 2 primary flexures

Answer 12

• Cervical: between spinal cord and rhombencephalon

- Cephalic: at the level of the mesencephalon, persists as union of cerebrum to brainstem