1/17 Development & Regeneration Of The Nervous System

Question 1

What embryologic layer contributes most to the brain/spinal cord?

Answer 1

Ectoderm

Question 2

What does ectoderm become?

Answer 2

Neural plate (folds dorsally until borders touch to make:)
Neural crest (borders)
Neural placode

Question 3

Where do neural crest cells migrate?

Answer 3

Laterally and ventrally

Question 4

What do neural crest cells form?

Answer 4

most of the peripheral nervous system including sensory and autonomic ganglia
(excluding derivatives of neurogenic placodes)

Question 5

What are neurogenic placodes associated with?

Answer 5

Cranial sensory systems:
Olfactory
Lens
Trigeminal
Otic
Geniculate
Petrosal
Nodose

Question 6

What does the olfactory placode form?

Answer 6

Not neurogenic
Olfactory epithelium

Question 7

What does the lens placode form?

Answer 7

Not neurogenic
Lens of the eye

Question 8

What does the trigeminal neurogenic placode form?

Answer 8

Trigeminal ganglion

Question 9

What does the otic neurogenic placode form?

Answer 9

Cochlear and vestibular

Question 10

What does the geniculate neurogenic placode form?

Answer 10

Geniculate ganglion & distal CN VII

Question 11

What does the petrosal neurogenic placode form?

Answer 11

Inferior glossopharyngeal ganglion & distal CN IX

Question 12

What does the nodose neurogenic placode form?

Answer 12

Nodose ganglion & distal CN X

Question 13

What does the neural tube separate from?

Answer 13

Separates from ectoderm

Question 14

What are the openings in the neural tube?

Answer 14

Cranial neuropore
Caudal neuropore

Question 15

What does the neural tube form?

Answer 15

The central nervous system

Question 16

What does the neural tube initially have, what happens to these?

Answer 16

Initially has 3 vesicles which separate into 5 vesicles

Question 17

What are the 3 vesicles of the neural tube?

Answer 17

Forebrain (prosencephalon)
Midbrain (mesencephalon)
Hindbrain (rhombencephalon)

Question 18

What are the 5 vesicles of the neural tube?

Answer 18

Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon

Question 19

What does the forebrain of the 3 vesicle stage become in the 5 vesicle stage?

Answer 19

Telencephalon
Diencephalon

Question 20

What does the midbrain of the 3 vesicle stage become in the 5 vesicle stage?

Answer 20

Mesencephalon

Question 21

What does the hindbrain of the 3 vesicle stage become in the 5 vesicle stage?

Answer 21

Metencephalon
Myelencephalon

Question 22

What does the telencephalon become in an adult?

Answer 22

Cerebrum

Question 23

What does the Diencephalon become in an adult?

Answer 23

Thalamus, hypothalamus, epithalamus, and retina

Question 24

What does the mesencephalon become in an adult?

Answer 24

Midbrain

Question 25

What does the metencephalon become in an adult?

Answer 25

Pons and cerebrum

Question 26

What does the myelencephalon become in an adult?

Answer 26

Medulla oblongata

Question 27

What are the types of neural tube defects?

Answer 27

Anencephaly Spina bifida

Question 28

What happens in anencephaly?

Answer 28

Cranial neuropore does not close

Question 29

What happens in spina bifida?

Answer 29

Caudal neuropore does not close

Question 30

What reduces neural tube defects?

Answer 30

Folic acid

Question 31

What happens to the neural tube in the 4th week?

Answer 31

differentiates into dorsal (alar plates) and ventral (basal plates) portions

Question 32

What are the dorsal and ventral portions the neural tube differentiates into? What do they do?

Answer 32

Alar plates – Dorsal – Sensory Basal plates – Ventral – Motor

Question 33

Where is the dorsal root ganglion come from?

Answer 33

The neural crest cells

Question 34

What is holoprosencephaly?

Answer 34

Failure of the forebrain to separate into distinct hemispheres. (regionalization)

Question 35

What is the severity of holoprosencephaly?

Answer 35

Varying levels of severity Most severe cases will not support life.

Question 36

What is the appearance of a person with holoprosencephaly?

Answer 36

Facial deformities primarily affect the eyes, nose and upper lip

Question 37

What are the causes of holoprosencephaly?

Answer 37

Causes are teratogens (i.e. alcohol) and/or genetic (loss of function mutations) Trisomy 13 is a common cause.

Question 38

What are the ways in which cell bodies of neuron migrate?

Answer 38

Radially or tangentially

Question 39

What is radial migration of neurons

Answer 39

from ventricles toward pial surface. • Except for cerebellum (pia to ventricle) • Layers of cerebral cortex build from inside to out

Question 40

What is tangential migration of neurons?

Answer 40

Involves interneurons

Question 41

What is lissencephaly?

Answer 41

Failure of neuronal migration Appears as a smooth brain Leads to intellectually disability Often accompanied by microencephaly

Question 42

What is the cause of lissenephaly?

Answer 42

Viral infections or genetic mutations

Question 43

What are the types of classifications of injury of peripheral neurons?

Answer 43

Seddon vs sunderland

Question 44

What are the classifications of neuronal injury according to seddon?

Answer 44

Neurapraxia, axonotmesis, neurotmesis

Question 45

What is neurapraxia?

Answer 45

Transient loss of function with minimal myelin damage

Question 46

What is axonotmesis?

Answer 46

Longer term loss of function with damage to axons while the epineurium remains intact

Question 47

What is neurotmesis?

Answer 47

Complete disruption of a nerve

Question 48

What are the classifications of neuronal injury according to sunderland?

Answer 48

1st degree-5th degree

Question 49

What is the 1st degree of neuronal damage?

Answer 49

Neurapraxia

Question 50

What is the 2nd degree of neuronal damage?

Answer 50

Damage of axon with intact connective tissue

Question 51

What is the 3rd degree of neuronal damage?

Answer 51

Damage of axon and endoneurium

Question 52

What is the 4th degree of neuronal damage?

Answer 52

Damage of axon, endoneurium, and perineurium

Question 53

What is the 5th degree of neuronal damage?

Answer 53

Neurotmesis Damage of all layers

Question 54

Can the 1st degree of neuronal injury heal?

Answer 54

Heals in minutes to weeks without additional care

Question 55

Can the 2nd degree of neuronal injury heal?

Answer 55

Heals at a rate of 1mm/day by following the existing connective tissue

Question 56

Can the 3rd degree of neuronal injury heal?

Answer 56

Possible surgery. Maybe heal at a rate of 1mm/day by following the existing connective tissue (usually incomplete)

Question 57

Can the 4th degree of neuronal injury heal?

Answer 57

Surgery will be needed. Recovery is poor and slow.

Question 58

Can the 5th degree of neuronal injury heal?

Answer 58

Surgery may be attempted. Recovery is unlikely.

Question 59

How do axons grow?

Answer 59

growth cones that sense guidance cues as to where they should grow

Question 60

What are the types of cues for axonal growth?

Answer 60

Adhesive, tropic, modulary

Question 61

What are adhesive cues?

Answer 61

found on surfaces or extracellular matrix (toward target cell)

Question 62

What are tropic cues?

Answer 62

attractants or repellants that cause intracellular changes in cytoskeleton growth

Question 63

What are modulatory cues?

Answer 63

change the sensitivity of the growth cones

Question 64

Can the CNS regenerate?

Answer 64

majority of the CNS will not regenerate if damaged Olfactory epithelium, subventricular zone, and subgranular zone can regenerate Increased by excercise

Question 65

How does the olfactory epithelium regenerate?

Answer 65

allows for the regrowth of neurons which reattach to the CNS

Question 66

How does the subventricular zone regenerate?

Answer 66

regenerates new cells that migrate to the olfactory bulb

Question 67

How does the subgranular zone regenerate?

Answer 67

contains stem cells that regenerate into part of the hippocampal circuitry

Question 68

What are the types of nerve damage?

Answer 68

Anterograde (Wallerian) degeneration affects the axon away from the cell body. Retrograde degeneration affects toward the cell body Axonal skeleton disintegrates and the membrane breaks apart Macrophages infiltrate the myelin sheath to clear the debris

Question 69

How does PNS regeneration occur?

Answer 69

Schwann cells accompany the macrophages and create a tube that produces growth factors. Within 4 days the nerve send out new growth The proximal portion develops a growth cone and will regrow at about 1mm per day.