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Flashcards in CNS development Deck (45):
1

What are all neurones and glia with cell bodies in CNS derived from

Neuroectoderm (neural plate)

2

How are neural crest cells induced

At lateral edges of neural plate due to combinatorial transcription code

3

What happens to neural crest cells

Epithelial mesenchymal transition, delaminate and migrate into periphery --> neurones with cell bodies in PNS

4

What structures are derived from neural crest cells

Melanocytes, sensory/autonomic ganglia, enteric neurones, Schwann cells and adrenal medulla cells

5

How can most neural tube defects be prevented

Folic acid

6

What happens in spina bifida

Failure of neural tube closure anywhere from cervical region caudally

7

How may spina bifida present

Worst form --> spinal cord and meninges protrude out
Less severe form--> lumbrosacral cutaneous abnormality e.g. tuft of hair

8

What determines patterning of neural tube

Morphogens e.g. Shh and BMPs

9

What do the pair of dorsal alar plates give rise to

Sensory (somatic and visceral) and interneurons

10

What do the ventral basal plates give rise to

Somatic and visceral motor neurones of spinal cord

11

What separates dorsal and ventral basal plates

Sulcans limitans

12

What morphogen specifies ventral basal plate

Shh

13

What morphogen specifies dorsal alar plate

BMPs

14

What is the cerebellum formed from

Outgrowth of alar plate of midbrain

15

Only...exists cranial to midbrain

Alar plate

16

What does dorsal alar plate give rise to

Sensory/integrative functions of thalamus, hypothalamus, basal ganglia and telencephalon

17

Compare alar plate in spinal cord and brainstem

Alar plate lies dorsolateral to basal plate as opposed to remaining dorsal in spinal cord

18

Describe 3 primary brain vesicles at rostral end of neural tube

Prosencephalon - forebrain
Mesencephalon - midbrain
Rhombencephalon - hindbrain

19

Describe 5 vesicle stage

Telencephalon --> end brain
Diencephalon
Mesencephalon --> midbrain
Metencephalon --> pons + cerebellum
Myelencephalon --> medullary brain

20

What does the prosencephalon consist of

Diencephalon and telencephalon

21

What does optic vesicle arise from

Arises as pair of diverticula from lateral forebrain (diencephalon)

22

How does optic vesicle proceed to develop

Proximal end --> optic stalk
Distal end laterally --> invaginates --> optic cup (outer layer of cup --> pigmented epithelium)
Axons from through optic stalk to form optic nerve
Optic vesicle induces formation of lens placode overlying ectoderm --> lens

23

What do olfactory bulbs sprout off

Ventral surface of each telecephalic vesicle

24

3rd ventricle grows at centre of...

Diencephalon

25

Lateral ventricles at centre of...

Telencephalon

26

What does telencephalon diff into..

Cerebral cortex , basal ganglia, hippocampus. olfactory bulb, amygdala

27

What does diencephalon diff into

Thalamus and hypothalamus

28

What do differnet parts of mesencephalic vesicles form

Dorsal surface --> tectum
Floor --> tegmentum

29

What does mesencephalon become

Midbrain

30

What does metencephalon become

Pons and cerebellum

31

What does myelencephalon become

Medulla oblongata

32

What is the cavity of the mesencephalon

Cerebral aqueduct

33

What is the cavity of the metencephalon and myelencephalon

4th ventricle

34

Describe positioning of somatic motor neurones and somatic+ visceral sensory neurones in brain stem

CENTRAL to LATERAL:Somatic motor neurones , then visceral sensory then somatic sensory

35

What happens to cavity of spinal cord

Constricts to form CSF filled spinal canal

36

Mature neurones do not undergo...

Mitosis

37

What are the limited sites of adult neurogenesis, describe their significance

Dentate gyrus of hippocampus --> formation of memories
Subventricular zone --> give rise to neurones for upper layers of cortex --> corticocortical connections located here. SVZ of ventral telencephalon persists in adults

38

What is the role of neural cell death in CNS development

Developing brain overproduces neurones (and glial cells) --> surplus neurones that fail to make synaptic connections removed by apoptosis through deprivation of neurotrophic factors.

39

When are the primary and secondary brain vesicles found in CNS development

3-4 weeks
5 weeks

40

Describe how axon outgrowth occurs once neural precursor cell reaches final destination and as it extends neurites (--> axons/dendrites)

Growth cone at tip of neurite identifies path for elongation as filopodia prove environment. Neurite grows when filopodium takes hold of substrate and pulls growth forwards

41

Describe how axons can grow together (coordinated)

Connections established at first by pioneer axons which later guide neighbour axons to same target
Axons growing together stick together by interaction of cell adhesion molecules on surface

42

What imposes topographic order on wiring of axons to targets

Gradients in expression of guidance cues and their axonal receptors

43

Describe the processes in synapse formation

Formed when growth cone comes in contact with its target
1) Dendritic filopodium contacts axon
2) Synaptic vesicles and active zone proteins recruited to presynaptic membrane (basal lamina factors from target cell -->Increase in Ca2+ in growth cone --> cytoskeletal changes and neurotransmitter release)
3) neurotransmitter receptors accumulate postsynaptically

44

Describe how some synaptic connections are reinforced

Nerve terminals that are coincidentally active cause LTP in post synaptic cell --> reinforced. --> selects functionally useful connections

45

Describe the mechanism for apoptosis of 50% of neurones in post natal crticial period

Input neurones compete for neurotrophic factors from post synaptic cells, taken up and transported retrogradely to cell soma --> switch off apoptosis genes