Lecture 16: Development of Nervous System

Question 1

What is the Critical Period during embryonic development?

Answer 1

• Weeks 3-8

- time period when things that can go wrong will most likely go wrong

Question 2

Somatic vs Autonomic systems

Answer 2

Somatic –> sensory/motor to muscle and skin (voluntary)

Autonomic –> smooth muscle, glands, cardiac (involuntary and unconcious)

Question 3

Dorsal/Lateral/Anterior parts of Spinal Cord (White vs Gray Matter)

Answer 3

White Matter (myelinated axons)
- Dorsal (sensory), Lateral (sensory/motor), Anterior (motor)

Gray Matter (cell bodies of neurons)
- Dorsal (sensory), Lateral (autonomic: visceromotor), Anterior (motor)

Question 4

Where does the neural tube form in comparison to somites?

Answer 4

Caudal to 4th pair of somites

Question 5

Alar vs Basal Plate

Answer 5

Alar (dorsal) plate –> sensory neurons

Basal (ventral) plate –> motor neurons

Question 6

What are the Ventricular, Intermediate, and Marginal Zones?

Answer 6

Ventricular –> closest to central canal
Intermediate –> Gray matter
Marginal –> White matter

Question 7

What cells are found in the Ventricular Zone, and what cell is found in the Marginal Zone?

Answer 7

Ventricular: ependymal cell and choroid plexus (makes CSF)

Marginal: oligodendrocyte

Question 8

Where is the position of the end of the spinal cord in adults vs newborns?

Answer 8

Adults: L1/L2

Newborns: L2/L3

Question 9

What do high lvls of BMP and Shh create?

Answer 9

BMP (dorsal roof plate/epidermis)
- PAX3/7 –> sensory neurons –> Alar plate

Ssh (ventral floor plate/notochord)
- NKX2.2 and NKX6.1 –> ventral neuron formation –> Basal Plate

Question 10

What is activated just dorsal to ventral neuron formation (basal plate) and what is created?

Answer 10

• slightly lower Ssh/higher BMP

- activates NKX6.1 and PAX6 = ventral motor neurons of ANTERIOR HORN

Question 11

Cells that develop from the neural tube (2)

Answer 11

• motor neurons

- pre-ganglionic autonomic neurons

Question 12

Efferent vs Afferent Neurons

Answer 12

Efferent = MOTOR

• Somatic: skeletal muscle
• Visceral: autonomic ganglion –> control smooth/cardiac muscle and glands

Afferent = SENSORY

• Somatic: sensory fibers from integument
• Visceral: sensory fibers from organs (viscera)

Question 13

What two structures do neural crest cells give rise to?

Answer 13

1. spinal ganglion cells

2. sensory neurons in periphery

Question 14

Sympathetic Autonomic Nervous System

Answer 14

• spinal cord in thoraco-lumbar region (T1-L2)
• LATERAL HORNS

Preganglionic (myelinated/short) to sympathetic ganglion
Postganglionic (non-myelinated/long) ganglia to viscera

Question 15

What are the 7 major sympathetic ganglion?

Answer 15

• superior, middle, inferior cervical ganglion
• celiac ganglion
• aorticorenal ganglion
• superior, inferior mesenteric ganglion

Question 16

Parasympathetic Autonomic Nervous System

Answer 16

• cranial-sacral region (CN 3, 7, 9, 10 and SN 2, 3, 4)
• neural crest components

Preganglionic (myelinated/long) to sympathetic ganglia
Postganglionic (unmyelinated/short) to viscera (in wall)

Question 17

What are the 4 major parasympathetic ganglion?

Answer 17

CN 3: ciliary ganglion
CN 7: ptergopalatine ganglion
CN 9: submandibular ganglion
CN 10: otic ganglion

Question 18

Myelination (Oligodendrocytes vs Schwann Cells)

Answer 18

• during late fetal period continue to first postnatal year

Oligodendrocytes (CNS –> Neural Ectoderm)

• lower brain stem (older tracts 1st)
• 6th month through puberty

Schwann Cells (PNS –> Neural Crest)

• motor roots before sensory roots
• 4th month