EMB: Eye Development

Question 1

The retina, Iris (smooth muscle), and ciliary body epithelium all come from ________.

Answer 1

Neural ectoderm

Question 2

The lens + cornea epithelium come from _______.

Answer 2

Surface Ectoderm

Question 3

The sclera, stroma of cornea, stroma of cornea, and strom of Iris all come from _______.

Answer 3

Mesenchyme

Question 4

What week does the eye start developing?

Answer 4

Week 4

Question 5

What 3 embryonic sources make up the eye?

Answer 5

Neuroectoderm, Surface ectoderm, mesoderm (blood vessels)/neural crest

Question 6

Where does the eye come from specifically?

Answer 6

The brain –> Diencephalon!!

Question 7

Question 8

What is the outer layer of the optic cup called?

Answer 8

Pigmented layer

Question 9

What is the inner layer of the optic cup called?

Answer 9

Inner layer

Question 10

What is the space in between the inner and outer layers of the optic cup called?

Answer 10

Intraretinal space

Question 11

What runs in the optic fissure?

Answer 11

Hyaloid A. + V.

Question 12

What is so important about the Smooth muscle cells of the Iris: Dialator + pupil constrictors?

Answer 12

They are the only 2 muscles in the entire body that don’t come from mesoderm!!!!

Instead they come from neuroectoderm :)

Question 13

In detachment of the retina, there is separation of the pigmented (inner) and neural retina (outer layer optic cup). What can cause this?

Answer 13

Down’s, Marfan’s, Trauma

Question 14

What is Aniridia?

Answer 14

Lack of iris tissure or complete absence of the iris.

Question 15

What causes aniridia?

Answer 15

Defect results from arrest of development at rim of optic cup during 8th week.

Pax6 gene mutation (can also affect ears)

Can be associated with glacoma + other cataracts

Question 16

When the lens tounches the optic cup what happens?

Answer 16

Lens induced –> lens placode –> lens pit –> lens vesicle + cornea

Question 17

What is the origin of cornea epithelium?

Answer 17

Surface ectoderm

stroma = NC cells

Question 18

What is this?

Answer 18

Congenital Cataracts

Lens = opaque + frequently appears grayish white

Question 19

What causes congenital cataracts?

Answer 19

Congenital galactosemia enzyme deficiency

Causes galactose from milk to accumulate in blood and tissues

Also

*Rubella can cause this, lens vulnerable between 4-7 weeks*

Question 20

The choroid (vascular) + sclera come from ______.

Answer 20

NC cells

Question 21

The posterior chamber _______ aqueous humor.

Answer 21

secretes

Question 22

The anterior chamber ______ aqueous humor.

Answer 22

Resorbs

Question 23

What is this?

Answer 23

Congenital Glaucoma

*whole eye looks hazy, not just lens like in cataracts*

Question 24

What causes congenital glaucoma?

Answer 24

Elevated intraocular pressure

Question 25

What is the underlying cause for elevated intraoccular pressure in congenital glaucoma?

Answer 25

Abnormal development of the drainge mechanism of aqueous humor (scleral venous sinus) of NC cells. Also, genetics = CYP1B1 gene + Rubella infection

Question 26

What is the blood supply for the eye?

Answer 26

1. **Hyloid A.** (in optic N.) --\> branches into central A. (for retina) 2. Choroidal Vessels (from cilliary A.'s)

Question 27

What is this?

Answer 27

Persistence of hyaloid A. The distal part persists, instead of degenerating

Question 28

What becomes the optic N.?

Answer 28

**Retinal ganglion axon cells** that grow back through, NOT OPTIC STALK (just template)

Question 29

What is this?

Answer 29

Papilledema

Question 30

What causes papilledema?

Answer 30

Increased intracranial pressure slows venous return from retina, causing fluid accumulation of the optic disc.

Question 31

What is this?

Answer 31

Coloboma

Question 32

What causes coloboma?

Answer 32

Optic fissure fails to close completely, leaving a gap in the eye structures - Iris comes from rim of optic cup-