Ii-20: Neurodevelopment I - Neurulation

Front 1

What are 3 determinative events that occur in nervous system development?

Back 1

1. Cells separate into distinct groups - morphological changes

2. Restrictions in cells' development potential

3. Intercellular signaling links mophological changes to restrictions in potential

Front 2

What occurs in general during neurulation?

Back 2

Formation of neural crest and neural tube

Front 3

What is gastrulation?

Back 3

Division of embryo into 3 germ layers: endoderm, mesoderm, and ectoderm

Front 4

When is neurulation initiated?

Back 4

When mesoderm signals the overlying ectoderm to divide into the neural tube, neural crest, and epidermis

Front 5

What do ventricular zone cells in the neural tube give rise to during neurulation?

Back 5

Neurons, astrocytes, and oligodendrocytes

Front 6

During neurulation, what forms at the ventral midline and dorsal midline?

Back 6

Specialized cells

Ventral midline = floor plate
Dorsal midline = roof plate

Front 7

What types of cells do Neural tube cells become?

Back 7

CNS

Front 8

What types of cells do neural crest cells become?

Back 8

PNS

Front 9

What are the major gene transcription factors involved in neural tube development? (5)

Back 9

1. Retinoic acid
2. Fibroblast growth factor
3. wnt
4. sonic hedgehog (shh)
5. Bone morphogenic proteins (BMP)

Front 10

What causes spina bifida?

Back 10

Failure of neural tube closure at the caudal end

Front 11

What causes anencephaly?

Back 11

Failure of neural tube closure at the rostral end; no forebrain or cerebellum forms

Front 12

What is the benefit for pregnant women of taking folic acid?

Back 12

decreases incidence of neural tube closure defects

Front 13

What is the problem with excess vitamin A in pregnant women?

Back 13

Disrupt neural tube closure and neuronal differentiation

Front 14

What can loss of SHH lead to?

Too much SHH signaling?

Back 14

holoprosencephaly (disrupted forebrain development)


Medulloblastoma (childhood tumor)

Front 15

How do local signals lead to neuron differentiation in general?

Back 15

Local signals --> transcription factors --> different neurons specified in the dorsal-ventral axis

Front 16

Where would you expect Pax3 to function to affect both neural crest development and neural tube closure?

What results from a mutation in the Pax3 gene?

Back 16

Lateral neural plate/dorsal neural tube

Wardenburg syndrome

Front 17

From what structure does the neural crest originate?

Back 17

Dorsal-most neural tube from cranial to lumbar regions

Front 18

What 3 types of cels do neural crest cells differentiate into?

Back 18

1. Neurons and glia (Schwann) in the PNS (sensory, autonomic, and enteric ganglia)

2. Neuroendocrine cells of the adrenal medulla

3. Non-neural cells such as melanocytes, cartilage and bone in the face, outflow tract of the heart

Front 19

What are 4 examples of Neural crest disorders?

Back 19

1. Hishprung's Disease: defect in migration of neural crest cells into the colon to form the enteric neurons of the colon

2. Cranial facial disorders: cleft palate

3. Pigment disorders: melanocyte migration defects

4. Neurofibromatosis: affects many neural crest-derived cell types

Front 20

What are the 4 regions of the neural tube?

Back 20

1. Forebrain (prosencephalon)
2. Midbrain (mesencephalon)
3. Hindbrain (rhombencephalon)
4. Caudal tube

Front 21

What structures derive from the forebrain?

Back 21

Telencephalon
Diencephalon

Front 22

What structures derive from the midbrain?

Back 22

Superior colliculus
Inferior colliculus

Front 23

What structures are derived from the hindbrain?

Back 23

Metencephalon
Myelencephalon

Front 24

What structures are derived from the caudal tube?

Back 24

spinal cord

Front 25

What are the structures derived from the telencephalon? (5)

Back 25

1. cerebral cortex
2. hippocampus
3. basal ganglia
4. basal forebrain nuclei
5. olfactory bulb

Front 26

What are the structures derived from the diencephalon of the forebrain? (3)

Back 26

1. thalamus
2. hypothalamus
3. retina

Front 27

What are the structures derived from the metencephalon? (2)

Back 27

Pons
cerebellum

Front 28

What are the structures derived from the myelencephalon (1)?

Back 28

medulla

Front 29

What patterns the embryo in the rostrocaudal axis?

Back 29

Hox transcription factors

Front 30

What is a rhombomere?

What is its function?

Back 30

progenitor cell of hindbrain

Guides axon outgrowth of cranial motor neurons

Front 31

From where are neurons, oligodendrocytes, and astrocytes originated?

In what order are they generated?

Back 31

Originate from neural progenitor cells located adjacent to the ventricle in the developing neural tube

Neurons first, then oligodendrocytes, then astrocytes

Front 32

In what mitotic state are progenitor cells in the ventricular zone?

What happens when progenitor cells give rise to neurons?

Back 32

Mitotically active

Neurons exit the cell cycle, migrate away from the ventricle to the final positions in the developing brain

Front 33

What type of division do progenitor cells undergo?

What are the properties of the daughter cells?

Back 33

asymmetrical divisions

One daughter remains a mitotically active progenitor; the other daughter exits cell cycle to become a neuron

Front 34

What is the birthdate of a neuron?

Back 34

When the daughter cell of the progenitor exits the cell cycle to become a neuron

Front 35

When are most neurons generated?

Back 35

Prior to birth

Front 36

Epidermis
a. Progenitor
b. Signaling factor

Back 36

a. Ectoderm
b. BMP

Front 37

What induces ectoderm --> neuroectoderm?

Back 37

Noggin/chordin

Front 38

What induces Neural tube --> roof plate?

Floor plate?

Back 38

Roof plate = TGF-b

Floor plate = Sonic hedgehog

Front 39

What induces neurogenesis from roof/floor plate cells?

Inhibits?

Back 39

bHLH genes

Notch

Front 40

What factors induce oligodendrogenesis?

Inhibit?

Back 40

Olig1/2, Nkx2.1

Proneural bHLH

Front 41

What factors induce astrogliogenesis?

Inhibit?

Back 41

Notch/Nrg

Proneural bHLH

Front 42

What is the role of Notch/bHLH in neurogenesis and gliogenesis?

Back 42

Notch and bHLH balance to determine whether a cell differentiates or remains as a progenitor cells

Front 43

How are neural crest cells guided along migratory pathways?

What happens to them along the way?

Back 43

Adhesion molecules in the ECM

Continue to get developmental cues from embryonic cells along the way

Front 44

From where do inhibitory neurons in the cerebral cortex derive?

Where do they migrate?

Back 44

Derive ventrally (floor plate), migrate dorsally in developing cortex

Front 45

From where do excitatory neurons originate?

Back 45

Dorsal telencephalon, ordered into layers

Front 46

What are radial glia?

What are radial glia processes?

Back 46

Neurons in the CNS migrate along processes

Radial glia = neural progenitor cells