Development of the Eye Flashcards

1
Q

What marks the beginning of eye development?

A

The optic grooves appearing at day 22.

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2
Q

Eyes are derived from which layers? (4)

A

Neuroectoderm
Surface ectoderm
Mesoderm
NCCs

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3
Q

The retina, posterior iris, and CN II are from:

A

Neuroectoderm

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4
Q

Lens and external corneal epithelium are from:

A

Surface ectoderm

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5
Q

The fibrous and vascular coats of the eye are from:

A

Mesoderm

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6
Q

The choroid, ciliary body, sclera and inner corneal epithelium is from:

A

NCCs

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7
Q

What is the optic vesicle?

A

A from the optic groove that protrudes into head mesenchyme to contact surface ectoderm.

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8
Q

How is the optic stalk formed?

A

The distal end of the optic vesicle contricts

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9
Q

How is the lens placode formed?

What does it eventually become as it invaginates? Then what does it become?

A

Surface ectoderm thickens.

The lens pit, then the lens vesicle once it loses contact with the surface ectoderm.

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10
Q

How is the optic cup formed?

A

The optic vesicles invagine and form the cup, a double layered structure of neuroectoderm.

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11
Q

What does the optic cup form?

What does the optic stalk form?

A

Retina

CN II

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12
Q

What structure is continuous with neural retina and optic stalk?

A

Optic disk

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13
Q

Which cells invaginate into the optic stalk to form CN II?

A

Ganglion cells

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14
Q

What are hyaloid BVs from?

What do they supply?

A

Mesenchyme of retinal fissures.

The fetal eye.

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15
Q

What causes closure of the optic stalk?

A

Retinal fissures

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16
Q

What happens to the hyaloid vessels distally and proximally?

A

Distally they degenrate.

Proximally they persist as central a. and v. of the retina.

17
Q

Which layers of the optic cup become the pigmented layer and neural retina?

A

The pigmented layer is the outer, thin layer.

The neural retina is the inner, thick layer.

18
Q

What space separates the retinal layers (pigmented and neural)?

A

Intraretinal space. It will degenerate.

19
Q

What does the inner layer (neural retina) of the optic cup become?

A

Becomes neuroepithelium.

Differentiates in photoreceptors, bipolar cells, and ganglion cells.

20
Q

Which cells of the neuroepithelium are closest to the outer pigmented layer of the retina?

A

Photoreceptor cells

21
Q

Sheaths of CN II

A

Outer dural sheath: from dura, thick, blends in with sclera.
Intermediate sheath: from arachnoid.
Inner sheath: from pia mater. Vascular and closely contacts nerve and BVs.

22
Q

Function of ciliary m.

A

Focus the lens

23
Q

How does the iris form?

What is unique about it?

A

The rim of the optic cup grow inward and partially covers lens.
It has both layers of optic cup.

24
Q

What are dilator pupillae m. and sphincter pupillae m. derived from?

A

Neuroectoderm of optic cup

25
Q

What cells determine eye color?

A

Chromatophores in the loose CT

26
Q

How does iris heterochromia occur?

A

Changes to sympathetic innervations of the eye

27
Q

Which part of the lens forms the transparent epithelial cells, the primary lens fibers?

A

Posterior wall of lens vesicle

28
Q

What does the tunica vasculosa lentis do?

A

They are BVs that invest the lens

29
Q

What is primary vitreous humor from?

A

NCCs

30
Q

How do the aqueous chambers communicate?

A

Through scleral venous sinus

31
Q

Layers that make the cornea

A

Surface ectoderm (external corneal epithelium)
Mesenchyme
NCCs

32
Q

How is the choroid and sclera made?

A

Both from mesenchyme (NCCs).

The inner layer is the choroid and the outer layer is sclera.

33
Q

Coloboma is from:

A

Incomplete closure of retinal fissure

34
Q

Congenital glaucoma

A

Abn increased introcular pressure in neonates.

Aqueous humor does not drain properly –> abn development of scleral venous sinuses.

35
Q

What is aniridua?

How does it occur?

A

Absence of the iris.

Arrested development at rim of optic cup (wk 8)

36
Q

Persistent hyaloid a. looks like what in the adult?

A

Worm-like squiggle projecting from optic disk.

Eye may be smaller.