Lecture 31: Eye Development Flashcards Preview

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Flashcards in Lecture 31: Eye Development Deck (33):
1

Ectodermal placodes

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

2

What is the primordium for Rathke's pouch?

Hypophyseal placode

3

What is the primordium for olfactory epithelium?

Olfactory placodes

4

What is the primordium for the lens?

Lens placodes

5

What is the primordium for cranial nerve V?

Trigeminal placodes

6

What is the primordium for the inner ear?

Otic placodes

7

What is the primordium for sensory neurons supplying visceral structures?

Epibranchial placodes

8

How does BMP concentration affect formation of placodes?

Low BMP concentration in preplacodal region leads to formation of placodes

9

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

D. Cornea

10

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?

Choroid fissue

11

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

Hyaloid artery

12

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

Pax6

13

How does absence of Pax6 affect mammals?

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

14

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

Inhibits expression of Pax6

15

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

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

16

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

Decreases expression of Pax6; Induces expression of Pax2

17

What is the function of Pax2?

Provides guidance of axons of ganglion cells of retina

18

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

Prevents formation of prospective lens in surrounding areas

19

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

Induces formation of lens placode from lens ectoderm

20

What is the effect of Foxe3 on Lens vesicle?

Separation of lens vesicle from surface ectoderm

21

What effect does FGF have on vitreous humor?

Stimulates formation of lens fibers

22

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

Underlying lens vesicle

23

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

Positive stimulation for migration between neural crest cells and ectoderm

24

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

Modulates TGFB production

25

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

Inhibits migration of periocular neural crest cells

26

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

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

27

What is responsible for differentiation of pigmented retina?

Oxt2 stimulated by Shh

28

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

Nasotemporal; ephrins, receptors

29

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

Notch

30

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

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

31

Anopthalmos

"Without eyes"

32

Micropthalmos

"Small eyes"

33

Coloboma

Failure of choroid fissure to close