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COB Embryology > Lecture 31: Eye Development > Flashcards

Lecture 31: Eye Development Flashcards

1
Q

Ectodermal placodes

A

Thickening in embryonic ectoderm constituting primordial group of cells from a sense organ

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2
Q

What is the primordium for Rathke’s pouch?

A

Hypophyseal placode

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3
Q

What is the primordium for olfactory epithelium?

A

Olfactory placodes

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4
Q

What is the primordium for the lens?

A

Lens placodes

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5
Q

What is the primordium for cranial nerve V?

A

Trigeminal placodes

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6
Q

What is the primordium for the inner ear?

A

Otic placodes

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7
Q

What is the primordium for sensory neurons supplying visceral structures?

A

Epibranchial placodes

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8
Q

How does BMP concentration affect formation of placodes?

A

Low BMP concentration in preplacodal region leads to formation of placodes

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9
Q

Neural crest derived cells constitute a significant component of which tissue of the eye?

A. Neural retina
B. Lens
C. Optic nerve
D. Cornea
E. None of the above
A

D. Cornea

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10
Q

What is the name of the groove that forms along the optic vesicle and is continuous with the optic stalk and posterior chamber of the eye?

A

Choroid fissue

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11
Q

What structure uses the choroid fissure and optic stalk to pass into the posterior chamber of the eye?

A

Hyaloid artery

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12
Q

Which gene is known as the “master gene for eye development”? Absence of this gene will lead to an eyeless mutant in Drosophila.

A

Pax6

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13
Q

How does absence of Pax6 affect mammals?

A

Early optic vesicle will form, but no other eye formation occurs - lens does not form

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14
Q

What is the effect of high [Shh] on Pax6?

A

Inhibits expression of Pax6

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15
Q

What is the effect of low [Shh] on Pax6?

A

In distal optic stalk, permits expression of Pax6 and development of optic vesicle, retina.

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16
Q

What are the effects of high [Shh] in the proximal optic stalk on Pax6 and Pax2?

A

Decreases expression of Pax6; Induces expression of Pax2

17
Q

What is the function of Pax2?

A

Provides guidance of axons of ganglion cells of retina

18
Q

What is the effect of downregulation of Pax6 by neural crest cells?

A

Prevents formation of prospective lens in surrounding areas

19
Q

What are the effects of FGF, BMP, and Pax6 on the optic vesicle?

A

Induces formation of lens placode from lens ectoderm

20
Q

What is the effect of Foxe3 on Lens vesicle?

A

Separation of lens vesicle from surface ectoderm

21
Q

What effect does FGF have on vitreous humor?

A

Stimulates formation of lens fibers

22
Q

What is responsible for the transformation of the overlying ectoderm from bi-layered epithelium to transparent multi-layered structure of the cornea?

A

Underlying lens vesicle

23
Q

What is the role of TGF-B in maturation of the cornea?

A

Positive stimulation for migration between neural crest cells and ectoderm

24
Q

What is the role of semaphorin 3A during maturation of the cornea?

A

Modulates TGFB production

25
Q

What is the role of neurophilin-1 in maturation of the corena?

A

Inhibits migration of periocular neural crest cells

26
Q

What is the role of hyaluronic acid in maturation of the cornea?

A

Secreted in primary stroma, causes swelling and enhances neural crest cell migration

27
Q

What is responsible for differentiation of pigmented retina?

A

Oxt2 stimulated by Shh

28
Q

Which axis of the retina is fixed first? What gradient is responsible for establishment of this axis?

A

Nasotemporal; ephrins, receptors

29
Q

Expression of what gene prevents cells in the retina from differentiating too early?

A

Notch

30
Q

Which axis of the retina is fixed second? What gradient establishes this axis?

A

Dorsoventral; Shh and BMP, with ventropin, Tbx-5, Pax2, Vax2

31
Q

Anopthalmos

A

“Without eyes”

32
Q

Micropthalmos

A

“Small eyes”

33
Q

Coloboma

A

Failure of choroid fissure to close

COB Embryology (24 decks)

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