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Developmental Neuroscience > Retina Development > Flashcards

Retina Development Flashcards

1
Q

When does eye development begin?

A

week 4 –> 8 years post natal

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2
Q

neural tissues (forebrain) forms

A

retina, RPE, iris, ciliary body

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3
Q

surface ectoderm forms

A

lens, eyelids, cornea

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4
Q

neural crest forms

A

cornea, ciliary body

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5
Q

mesenchyme forms

A

sclera, blood vessels

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6
Q

5 parts of neural tube

A 
telencephalon 
diencephalon 
mesencephalon 
metencephalon 
myelencephalon
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7
Q

Eyes are outgrowings of?

A

the diencephalon - optic vesicles

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8
Q

optic vesicles reach what and what happens?

A

surface ecoderm - induces lens placode

optic cup folds - bilayer optic cup

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9
Q

posterior region of optic cup

A

optic stalk - blood vessels and axons

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10
Q

lens placode invaginates to form what?

A

lens vesicle

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11
Q

what does lens placode lose contact with?

A

surface epithelium

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12
Q

2 parts of optic cup

A

retina and RPE

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13
Q

what does lens vesicle make?

A

lens

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14
Q

what induces formation of cornea?

A

signals from lens

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15
Q

spemann and Lewis, 1900

A

amphibians - contact of optic nesicle with surface ectoderm - form lens
remove optic vesicle = no lens placode

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16
Q

Later optic vesicle/lens induction experiments

A

lens like structure can form

differences in timing of inductive events between species

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17
Q

Can all ectoderm form a lens? why?

A

no - at gastrulation head ectoderm bias towards lens fate

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18
Q

optic vesicle transplanted to trunk

A

no lens

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19
Q

lens signalling back to optic vesicle

A

lens induce expression in distal optic cup of genes - Chx10, Lhx2 for neural retina development

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20
Q

dissect of epithelium or rotate optic vesicle - retina genes

A

no expression as no lens

retina genes where normally RPE

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21
Q

signals from where pattern optic cup?

A

lens and extraocular mesenchyme

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22
Q

extraocular mesenchyme - RPE genes

A

upregulate

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23
Q

where is pax 6 expressed?

A

widely in developing eye - optic cup and lens vesicle

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24
Q

master regulator of eye development

A

pax6

25
Q

mouse - pax 6

A 
\+/- = microphthalmia - small eyes
-/- = no eyes
26
Q

Pax 6 +/- humans

A

no iris, cataract, glaucoma

27
Q

other genes essential for eye development

A

Rx - retinal homeobox

six3

28
Q

genes eye development - early distribution

A

pax 6, rx and six 3 continuous across early neural plate

single eye field

29
Q

What splits eyefield in two?

A

shh in midline of neural tube

30
Q

what does shh activate?

A

expression of genes required for optic stalk development eg pax 2

31
Q

what does shh repress?

A

expression of genes required for optic vesicle development eg pax 6

32
Q

pax 6 and pax 2

A

mutual repressors

33
Q

cyc -/- or shh -/-

A

pax 6 not repressed at midline - no activation of pax2

form single large optic cup

34
Q

increased shh in midline

A

increased repression pax 6 and increased activation pax 2

smaller eye field

35
Q

cyclopia in humans

A

rare
disrupt shh signalling
associated with cranial defects
lose midline structures

36
Q

what is nasal/temporal and dorsal/ventral patterning of retina needed for?

A

visual function - green cones in dorsal and blue cones ventral
mapping retina onto visual targets - positional identity

37
Q

what cells relay visual info from eye to brain?

A

RGC

38
Q

primary target of RGC

A

amphibians = tectum

humans - LGN, some to superior colliculus

39
Q

dorsal and ventral RGC axons to tectum

A

dorsal - lateral

ventral - medial

40
Q

nasal and temporal RGC axons to tectum

A

nasal posterior

temporal - anterior

41
Q

transcription factors imposing n/t and d/v specificty of optic cup

A

nasal - Foxg1 and SOHO1
temporal - Foxd1
dorsal - Tbx5
ventral - Vax2

42
Q

What does vax 2 in ventral retina induce expression of?

A

EPHBs

43
Q

Express EPHB in dorsal retina also or KO

A 
dorsal = ventral and dorsal RGC map medially 
KO = both map laterally
44
Q

retina cell types

A

6 neuronal cell types and muller glia

rods, cones, horizontal, bipolar, amacrine, RGC

45
Q

Retinal progenitor cell fate

A

became all major types but biased

46
Q

generation of retinal cell types

A

stereotypical sequence

ganglion cells first, amacrine, horizontal, cones, rods, bipolar, muller glia

47
Q

waves of retinal neurogenesis

A

central - peripheral

48
Q

ciliary margin

A

far peripheral retina

neurogenesis continues here in lower vertebrates throughout life - stem cells?

49
Q

asymmetric and symmetric division of progenitor cells

A 
symmetric = 2 progenitor or undifferentiated cell 
asymmetric = 1 of each
50
Q

where are RGC found?

A

inner most surface of retina

51
Q

where do progenitor cells divide?

A

adjacent to RPE

52
Q

what happens to progenitors that differentiate as RGC?

A

basal process to vitreal surface
nucleus migrates
axon extends into OFL
break attachment of apical surface

53
Q

what triggers the initial central patch of differentiated RGCs?

A

FGFs

54
Q

evidence for FGF - central RGC

A

FGF expressed in central retina/optic stalk before neuogenesis
block FGF inhibits neurogenesis

55
Q

what drives RGC differentitation in fish?

A

shh

56
Q

RGC differentiation in fish

A

wave of shh - self propagating

disrupt shh signal = neurogenesis initiates but fails to spread normally

57
Q

commitment to RGC fate - important

A

notch/delta signalling - premature differentiation, overproduction RGC
Atho7 - no RGC
Islet2 - born but fail to differentiate and die

58
Q

retinal cell types - bias

A

eg VC1.1 -ve = cones
+ve = amacrine/horz
+ve then -ve = rods

59
Q

generation of retinal cell types

A

cannot go back or skip a step
controlled by transcription factors
environment

Developmental Neuroscience (10 decks)

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