Neuroembryology - Lecture 5

Question 1

Key Steps of Prenatal Development

Answer 1

1. neurulation
2. Neurogenesis, migration, & differentiation
3. Growth of brain and spinal cord
4. Myelination of axons

Question 2

Neurulation

Answer 2

neural tube formation

anterior and posterior neuropore close weeks
2.5 - 4

Question 3

what leads to formation of 5 brain vesicles

Answer 3

neurogenesis, migration, and differentiation

Question 4

neurogenesis, migration, and differentiation occurs during what period

Answer 4

embryonic

weeks 4-8

Question 5

timeframe of myelination of axons

Answer 5

begins in 5-6th month

ends 4th-5th decade of life

Question 6

neurulation

Answer 6

neural tube formation

Question 7

neurulation steps

Answer 7

neural plate –> neural tube –> neural crest

Question 8

neural tube derives from

Answer 8

CNS

Question 9

neural crest derived from

Answer 9

PNS

Question 10

spina bifida

Answer 10

posterior neuropore in fails to close during embryonic period

Question 11

three primary brain vesicles and flexures

Answer 11

• prosencephalon (forebrain)
• mesencephalon (midbrain)
• rhombencephalon(hindbrain)

Question 12

at the 6th week of neural tube development what is present?

Answer 12

five secondary vesicles and two curvatures

Question 13

telencephalon lateral out-pocketing comes during neural tube formation (6th week) comes from

Answer 13

cerebral hemispheres

Question 14

telencephalon ventral out-pocketing during neural tube formation (6th week) comes from

Answer 14

olfactory bulbs

Question 15

what is visible during 6th week of diencephalon

Answer 15

3rd ventricle, optic vesicles, optic chiasm, optic nerve and mammillary bodies

Question 16

alar plate

Answer 16

posterior/dorsal

afferent (sensory)

Question 17

basal plate

Answer 17

anterior/ventral

efferent(motor) structures

Question 18

what side of the body is sensory information on

Answer 18

lateral

Question 19

what side of the body is motor information on

Answer 19

medial

Question 20

what chemical messengers are found in the basal plate

Answer 20

sonic hedgehog

Question 21

neuroblasts

Answer 21

forms neurons found in CNS

Question 22

gliobasts

Answer 22

forms supporting cells in CNS

Question 23

embryonic period: week 4-8

Answer 23

neurogenesis & migration of neuroblasts in spinal cord and brain

Question 24

migration of neuroblasts

Answer 24

migrate from ependyma out into spinal cord or cortex

Question 25

what are the cells of the neural tube wall considered

Answer 25

neuroepithelial cells | ependymal cells

Question 26

radial glial cells used as scaffolds

Answer 26

attach interior to exterior *neurons will ride glial cells until they get placed (inside-->out)

Question 27

Week 9-40 (fetal period)

Answer 27

growth of brain and cord synapse begin cell bodies are placed - axons need to travel long distance

Question 28

during the fetal period neurons become ___

Answer 28

motor neurons either sensory or motor

Question 29

growth cones

Answer 29

lamellipodia & fliopodia

Question 30

lamellipodia

Answer 30

send sharp projections called filopodia

Question 31

fasciculation

Answer 31

axons bind together and grow in unison | get ride from extracellular matrix or axon

Question 32

does the ventral side of the spinal cord have attractants or repellants?

Answer 32

both

Question 33

chemoattractant = red

Answer 33

lamellipodia have receptor for attractant netrin moves toward high concentration & expresses ROBO

Question 34

chemorepellent = blue

Answer 34

robo - receptor for slit and slit is repellant this makes sure axon does not cross back and continues on this side

Question 35

synaptic formation

Answer 35

growing nerve secretes protein that triggers post synaptic changes

Question 36

post synaptic changes during synaptic formation

Answer 36

neurotransmitter receptors congregate surface configuration

Question 37

neurotransmitter receptor congregate effects

Answer 37

pre-synpaitc moves toward end plate and gets fixed in receptors on post-synaptic membrane group together forms stable synapse

Question 38

3rd month: 9th - 12 week (fetal period)

Answer 38

fetus doubles its length brain grows until nearly complete (neurogenesis and axon regrowth)

Question 39

4 month: 9-40 weeks (fetal period)

Answer 39

spinal motor neurons grow into periphery and begin to innervate muscles = onset of motor activity formation of reflex circuits in spinal cord

Question 40

5th month : 17-20 weeks (fetal period)

Answer 40

myelination of spinal cord (gliogenesis)

Question 41

6th month: 21-24 (fetal period)

Answer 41

cerebral cortex layers form maturation of neurons brain & spinal cord

Question 42

8 month: week 29-32

Answer 42

pupillary light reflex | taste sense operative

Question 43

9th month: week 33-38

Answer 43

fetus has firm hand grip and orients to light full skin sensitivity

Question 44

week 40

Answer 44

myelination of brain begins (gliogeneiss) --> continues into 5th decade

Question 45

post natal brain growth is due to:

Answer 45

- increase in size of neurons - increase in number of supporting cells (glia) - development of neural processes and synapses - laying down insulation of nerve processes

Question 46

rate of synapse formation with age

Answer 46

synapses are formed very rapidly at early months of life achieving maximum density b/w 6-12 months after birth decrease after that due to disuse of natural attrition this is why it is vital to learn at early age

Question 47

consolidation

Answer 47

programmed cell death to eliminate extra neurons

Question 48

pruning

Answer 48

- eliminate improperly connected neurons and axons - eliminate neurons and axons that are phylogenetically no longer needed - to eliminate over produced neurons or axons

Question 49

apoptosis

Answer 49

cell death is genetically programed reflects competition for trophic factors

Question 50

trophic factors

Answer 50

life sustaining substance neurotrophies

Question 51

neurotrophies

Answer 51

nerve growth factor save neurons by switching off genetic programing

Question 52

peripheral nervous system derived from 3 sources

Answer 52

- neural crest cells - neural tube - mesoderm

Question 53

neural crest cells

Answer 53

peripheral ganglia, schawnn cells, and afferent nerve fibers

Question 54

neural tube

Answer 54

preganglionic autonomic fibers, & all fibers that innervate skeletal muscle

Question 55

mesoderm

Answer 55

dura mater and connective tissue coverings of the peripheral nerve fibers (endoneurium, perineurium, and epineurium)