Neuroembryology

Question 1

neurulation

Answer 1

folding process that transforms the neural plate into the neural tube

Question 2

when does neurulation start? finish?

Answer 2

starts 3rd week

cranial end closes on day 25

caudal end closes on day 28

Question 3

ectoderm overlying the notochord thicken to form…

Answer 3

neural plate

Question 4

lateral edges of neural plate become…

Answer 4

neural folds

Question 5

cells from the apices of the neural fold separate from neural tube to form…

Answer 5

neural crest

Question 6

neural folds meet in _______ and proceeds ________

Answer 6

occipital region

cranially AND caudally

Question 7

what represents the site of closure for the cranial neuropore?

Answer 7

lamina terminalis

Question 8

spina bifida occulta

Answer 8

vertebral arch defect only

tuft of hair over site

Question 9

spina bifida cystica

Answer 9

vertebral arch defect with herniation

-can either have meningocele or meningomyelocele

Question 10

meningocele

Answer 10

meninges protrude through vertebral arch and skin

Question 11

meningomyelocele

Answer 11

meninges AND spinal tissue protrudes thorugh vertebral arch and skin

Question 12

rachischisis

Answer 12

neural folds fail to elevate or close forming a flattened mass of neural tissue

Question 13

three caudal neural tube defects

Answer 13

spina bifida occulta

spina bifida cystica

rachischisis

Question 14

4 cranial neural tube defects

Answer 14

meningocele

meningocephalocele

meningohydrocephalocele

anencephaly

Question 15

meningocele (cranial)

Answer 15

meninges herniate through occipital bone defect

Question 16

meningoencephalocele

Answer 16

meninges and brain tissue herniate through occipital bone defect

Question 17

meningohydroencephalocele

Answer 17

meninges, brain and part of ventricular system herniate through an occipital bone defect

Question 18

anencephaly

Answer 18

failure of anterior neuropore to close

-most of skill roof and/or brain is absent

Question 19

neural crest gives rise to…

Answer 19

melanocytes

dorsal root ganglia

schwann/satellite cells

sympathetic/parasympathetic ganglia

medulla chromaffin cells

thyroid c cells

dentin

facial skeleton

Question 20

if neural crest cells dont migrate normally –>

Answer 20

facial deformities (clefts), congenital megacolon, or albinism

Question 21

neuroepithelium

Answer 21

composes the neural tube

-thick pseudostratified epithelium that are pluripotent stem cells

Question 22

neuroepithelium is pluripotent and gives rise to…

Answer 22

all the neurons and macroglia of the CNS

(neurons, oligocendrocytes, and astrocytes)

Question 23

neuroepithelium composes what zone?

Answer 23

ventricular zone

Question 24

neurogenesis

Answer 24

neurons are generated from neural stem cells and progenitor cell

-neuroepithelium –> neuroblasts which are postmitotic(cannot divide) –> aggregate in mantle zone which surrounds the ventricular zone

–they differentiate from round and apolar to bipolar/multipolar with axon and dendrocytes

Question 25

what composes mantle zone? ventricular zone? which surrounds which?

Answer 25

m - neuroblasts v- neuroepithelium mantle surrounds ventricular

Question 26

what layer surrounds the mantle? what is it made of?

Answer 26

marginal zone axons that sprout from the neuroblasts form this layer of white matter around the mantle

Question 27

when does neurogenesis finish?

Answer 27

6 months exception: cerebellum cell proliferation continues throughout first postnatal year

Question 28

after neuroblast production is complete, neuroepithelial cells of ventricular zone give rise to ...

Answer 28

glial precursors (glioblasts) that differentiate into the macroglia of the CNS

Question 29

after glioblasts are produced, the remaining reuroepithelial cells of the ventricular zone differentiate into...

Answer 29

ependymal cells that line the central canal of the spinal cord and the ventricles of the brain

Question 30

myelination

Answer 30

myelination begins in the 14th week/third trimester of fetal development, although little myelin exists in the brain at the time of birth --\> continues post-natally mostly done by 2nd year but can continue for two decades \*\*acquisition of developmental milestones correlates to myelination of specific tracts/paths

Question 31

most brain tumors arise from...? why?

Answer 31

glial and meningeal cells because most neurons are postmitotic so they cannot proliferate into tumors

Question 32

what two layers create the spinal cord

Answer 32

mantle and marginal zones

Question 33

mantle layer of spinal cord differentiates into ...

Answer 33

alar and basal plates

Question 34

what marks the junction of alar and basal plates

Answer 34

sulcus limitans

Question 35

alar plates become --\> basal plates become --\>

Answer 35

alar - doral horns (sensory neurons) basal - ventral horns (motor neurons and preganglionic autonomic neurons)

Question 36

marginal zone of spinal cord becomes...

Answer 36

white matter of spinal cord which is external to the gray matter

Question 37

what marks the junction of the spinal cord and hind brain

Answer 37

cervical flexure

Question 38

what flexure is at midbrain?

Answer 38

cephalic flexure

Question 39

3 primary vesicles of brain

Answer 39

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

Question 40

what flexure divides the rhombencephalon

Answer 40

pontine flexure divides into myelencephalon and metencephalon

Question 41

5 secondary vesicles of brain

Answer 41

prosen--\> telencephalon (rostral) and diencephalon (caudal) mesen--\> mesencephalon rhomben--\> metencephalon and myelencephalon

Question 42

what are the adult derivatives of... - telencephalon - diencephalon - mesencephalon - metencephalon - myelencephalon

Answer 42

- cerebral hemispheres/lateral ventricles - thalami/hypothalamus and 3rd ventricle - midbrain/aqueduct - pons and cerebellum/upper part of 4th ventricle - medulla/lower part of 4th ventricle

Question 43

there are no ____ in the brainstem

Answer 43

sympathetic nuclei

Question 44

midline of cerebellum

Answer 44

vermis

Question 45

cerebellum growth

Answer 45

from metencephalon rhombic lips meet at vermis --\> cerebellum hemispheres ar elateral to vermis later growth is in a dorsal direction --\> very rapid growth of surface layers creates an extensive pattern of foliation

Question 46

what forms the olive and pontine nuclei

Answer 46

rhombic lips

Question 47

telencephalon development

Answer 47

expands as c shape cortex lateral to the lentiforn nucleus is overgrown by parts of the adjacent frontal, temporal, and parietal lobes forming the insula major commisures (anterior commisure and corpus callosum) appear in the region of lamina terminalis anterior commisure maintains postion and CC grows in a hook shape