Development of the NS

Question 1

What is the carnegie system?

Answer 1

A classification system of early vertebrate development into 23 stages for better comparison between species

Question 2

Howmany germ layers does a human zygote have by embryonic week 3?

Answer 2

3

Question 3

What is the neural plate?

Answer 3

The thick medial part of the ectoderm, aka. the neuroectoderm

Question 4

What is neurolation?

Answer 4

The formation of the neural tube

Question 5

What are the three primary brain vesicles called, and what do they develop into respectively?

Answer 5

Prosencephalon –> forebrain
Mesencephalon –> mesencephalon
Rhombencephalon –> pons, medulla oblongata and cerebellum

Question 6

What are the secondary brain vesicles, and what do they develop into respectively?

Answer 6

Telencephalon
Diencephalon
Mesencephalon
Metencephalon –> pons and cerebellum
Myelencephalon –> medulla oblongata

Question 7

What is a flexure?

Answer 7

A bending of the neural tube

Question 8

Where does the mitosis take place?

Answer 8

Close to the ventricular system

Question 9

What is the sulcus limitans?

Answer 9

• A functional border between the sensory- and the motor system
• Divides the alar- and basal plate
• The caudal part of thee neural tube

Question 10

Describe the development of the spinal cord.

Answer 10

Sulcus limitans –> central canal
Alar plate –> dorsal horn
Basal plate –> ventral horn

Question 11

Where does the proliferation during the development of the cerebellum take place?

Answer 11

The proliferation takes place on the outer layer

Question 11

Describe the development of the telencephalon.

Answer 11

Develops as lateral evaginations from the prosencephalon

Question 11

Describe the development of the diencephalon.

Answer 11

Develops as the medial part of the prosencephalon

Question 11

Where does the retina develop from?

Answer 11

The diencephalon

Question 12

What does the thin dorsal and superficial telencephalon give rise to?

Answer 12

The cerebral cortex

Question 13

What does the thick ventral and deep telencephalon give rise to?

Answer 13

The BG

Question 14

How does the hippocampus migrate in the human telencephalon?

Answer 14

By sulci formation

Question 15

What does a neural stem cell give rise to?

Answer 15

Neurons, oligodendrocytes and astrocytes

Question 16

Where are the microglia developed?

Answer 16

In the immunesystem (yolk sac) migrating to the brain

Question 17

What are spina bifida?

Answer 17

An incomplete closure of the neural tube, can be caused by lack of folic acid

Question 18

How are the developmental transcription factors regulated, and how are the expression pattern?

Answer 18

Regulation maintained by positive/negative feed back loops, tightly regulated
Expression pattern: regional

Question 19

What does the HOX genes control?

Answer 19

Segmentation of the spinal cord and the hindbrain, and A/P fate

Question 20

What is early pattering of the neural tube based on?

Answer 20

Simple combinations of gradients

Question 21

How are the combination gradient of WNT in the neural tube?

Answer 21

The more caudal, the more WNT

Question 22

What are Noggin and SHH (sonic hedge hog) important for, and where are they secreted?

Answer 22

Neural tube formation
Secreted from notochord

Question 23

What are SHH also important for?

Answer 23

Ventrilization and development of the two hemipheres

Question 24

Describe the development of the segmented spinal cord.

Answer 24

Controlled by a dual RA:FGF8 gradient which continuously moves as each segment is formed (less RA the longer down the segments)

Question 25

Describe the three zones of the midbrain.

Answer 25

Ventricular zone: proliferating progenitors
Intermediate zone: early postmitotic cells
Mantle zone: mature neurons

Question 26

What are the functions of the radial glial cells during development?

Answer 26

Facillitate migration of newborn neurons, as they touch both surface of the brain
Neural stem cells

Question 27

How are the cortical layer formed?

Answer 27

Deepest layers are formed first (inside-out development)

Question 28

Why are rodents not a good model for development of the cortical layer?

Answer 28

Primatescortex is bigger, and primates posses an outer subventricular zone, which rodents does not

Question 29

What are the progenitors of the PNS cells, and where are they formed?

Answer 29

Neural crest progenitor, formed in the most dorsal part of the neural tube

Question 30

How are the NS finetuned?

Answer 30

“innervate or die” –> the target cells release specific survival factors when innervated

Question 31

What is a growth cone?

Answer 31

A neurite outgrowth searching for the correct targt cell by chemoattraction/repulsion

Question 32

What are formed first: neurons or glial cells?

Answer 32

Neurons - most glial cells are formed after birth

Question 33

What are the main reason humans take longer to walk?

Answer 33

We lack oligodendrocytes when we´re born

Question 34

What are the two sites of adult neurogenesis in rodents?

Answer 34

The subventricular zone, and the dentate gyrus of the hippocampus (memory)

Question 35

Are there stem cells in the brain?

Answer 35

Yes, but very few, and not very active

Question 36

What are pluripotent stem cells?

Answer 36

Embryonal stem cells –> can give rise to all cells in the body

Question 37

What are the challenge of neural stem cells?

Answer 37

There are no “universal” neural stem cell, thus pattering must take place very early in neural differentiation