Development of the Central Nervous System: Gondre-Lewis

Question 1

Repeat of Ziermann

Answer 1

????

Question 2

somites give rise to

Answer 2

segmentation of the body plan

Question 3

The ectoderm gives rise to what?

Answer 3

nervous system, integument, pigment cells

Question 4

The mesoderm gives rise to what?

Answer 4

bones, muscles, connective tissue, blood vessels

Question 5

The endoderm gives rise to what?

Answer 5

gastrointestinal tract, lungs, liver

Question 6

What are the mesodermal derivatives?

Answer 6

Paraxial Mesoderm: closest to midline; thick; forms somitomeres which give rise to mesenchyme of head and organize into somites at occipital and caudal levels to eventually form vertebral column, limb, body wall musculature

Intermediate: Urogenital system

Lateral Plate Mesoderm: thin, lateral; line peritoneal, pleural, and pericardial; thin membrane around each organ, vessels, etc.

send signals to one another to induce each other’s formation

Question 7

notochord formation

Answer 7

forms the body its longitudinal axis; gives body the left and right demarcation
-signals that set the midline of the CNS as it develops (brain)

• notochord has cranio-caudal axis of formation
• solid rod, important in establishing body’s longitudinal axis
• mesodermal origin
• induces columnar epithelial celsl above to become the neural plate

Question 8

parts of mesoderm that migrated first are part of the cranial

Answer 8

????

Question 9

What is the first event in the formation of the nervous system?

Answer 9

formation of the neural plate

• inducing substances from notochord diffuse to epiblast and activate gene transcription
• cells differentiate into a thick plate of columnar epithelial cells: thickening of epiblast layers cranial to the primitive pit; differentiates craniocaudally

concomitantly with the somites

• see hindbrain at Day 20
• formation of neural plate is the first event in the formation of the nervous system

Question 10

How does induction take place? How are axes established? What are organizers?

Answer 10

• as they migrate through the primitive node they change their identity
• any mesodermal that migrates through primitive node and cranially will be paraxial mesoderm

Question 11

What are examples of organizers?

Answer 11

Bone Morphogenetic Protein-4 (BMP-4) – ventralizing signal for Intermediate Mesoderm and Lateral mesoderm (as it goes through the node this is no longer expressed (antagonized)

-Chordin, Noggin, Follistatin antagonize actions of BMP-4 (and;FGF).

Question 12

They don’t get antagonized with chordin, noggin???

Answer 12

????on the Mesodermal Derivatives slide

Question 13

Molecular regulation of neural induction !!
How are axes established?
BMP-4 in ectoderm

Answer 13

cranial-caudal axis
ventral-dorsal axis

if BMP-4 is activated ectoderm becomes neuralized

where the midbrain and forebrain form will be induced by chordin, noggin, and follistatin????

caudal neural plate structures (hindbrain & spinal cord) depends on different secreted proteins from notochord, Wnt-3a and FGF, as antagonizers of BMP-4

Question 14

Why is retinoic acid also an important organizer?

Answer 14

induces those homestatiic HOX gene expression

Question 15

closest to the neural tube

farthest to neural tube

Answer 15

ventral????

skin (dorsal)

Question 16

They change the shape of the overlying tissue

Answer 16

the ends have a different influence than the ones on the midline

the change of the shape of the columnar???to form the ectodermal ridges

as this rises this confirmational change of the overlying ectoderm that is no longer influenced by the?????

Question 17

neural tube formation ends by 26 days

closing of neural tube at day 24

Answer 17

15-26 you get induction of the neural plate and closure of the neural tube

Question 18

Neural crest cells

Answer 18

• we have somites of mesodermal origin
• the spaces in the neural tube will become ventricles of the brain (with CSF)
• the arrows represent the migration of the neural crest cells
• the fate of the neural crest cells is controlled by the local environment of the body

for example: cells that take superficial pathway, just beneath the ectoderm will form pigment cells of the skin

-completed by day 26

Question 19

What are neuronal derivatives?

Answer 19

ganglia of the PNS

• dorsal root ganglia
• autonomic sympathetic chain ganglia
• parasympathetic ganglia
• cranial nerve ganglia

neural-like cells of the adrenal medulla
-important support cells

EVERYTHING THAT IS NOT CNS!!! (EXAM QUESTION!!)

Question 20

Secondary neurulation

Answer 20

develops CNS up to somite day 37

-this process ???

Question 21

neural tube defects

Answer 21

it is not related to a specific race you find them in hispanics, white, AA

-at some point UK was shown to be greater than JApan (associated with diet)

Question 22

there are different places where the above can happen

Answer 22

anterior notocord does not enclose properly

posterior notochorddoes no enclose properly

Question 23

spina bifida where it occurs at the level of the spinal cord

Answer 23

occulta

meningocele

meningeomyocele is the most severe: neural tissue is sitting outside of the bony cavity and is exposed to the external environment

Question 24

???

Answer 24

???

Question 25

???

Answer 25

??

Question 26

Holoprosencephaly

Answer 26

cranio-facial anomaly

Question 27

The eye and retina are nerual srtuctures

Answer 27

???

Question 28

?????

Answer 28

from the mesenchyma ????? and spinal cord

Question 29

What becomes the cerebellum?

Answer 29

???

Question 30

prosencephalon, mesencephalon, and myelocephalon

Answer 30

have different organizers that demarcates boundaries

Question 31

Hox genes are organizers of the hindbrain.

Answer 31

???

Question 32

Cytodifferentiation

Answer 32

cells that give rise to the
that single neural epitheliual cell the first cell it generates give rise to neuroblast–>neurons

?????

Question 33

alar plate

Answer 33

sensory association area

Question 34

basal plate

Answer 34

motor neurons

Question 35

4 slides showing the same thing what thing??

Answer 35

????

Question 36

What is the major difference between the brainstem and medulla?

Answer 36

???

Question 37

Forebrain is like the SC and the brainstem except

Answer 37

it is more complicated

• instead there are more rounds of neuroblasts differentiation ( the cerebral cortex ????)
• layering occurs in an inside-out pattern of lamination
• more complex

-grows out of ventricular zone proliferations (radial migrations)

Question 38

tangential migration

Answer 38

• medial ganglionic eminence that travel far form their birth to reside in Layer IV of the cerebral cortex; give rise to interneurons
• rostral migratory stream

Question 39

What is the difference between radial and tangential migration?

Answer 39

test questions????

Question 40

Lissencephaly

Answer 40

smooth brain when there errors in migration (failure of induction of migration)

Question 41

How does the axon know where to go?

Answer 41

• it needs to follow molecular cues (some are repulsive or attractive or both
• growth cones

Question 42

commissural axons

Answer 42

anything that crosses the midline

Question 43

Robo is a repulsive to slit and silences DCC

Answer 43

the farther away from midline the axon goes

Question 44

Agenesis of the corpus callosum (ACC)

Answer 44

there is a lack of axon guidance occurring to get it to where it needs to go cross the midline