Eye Development

Question 1

Ectoderm gives rise to:

Answer 1

lens and part of the cornea

Question 2

Neuroectoderm gives rise to:

Answer 2

retina, the pigmented epithelium of the iris, the optic nerve

Question 3

Neural crest cells give rise to:

Answer 3

choroid, sclera, part of the cornea (corneal endothelium)

Question 4

Mesoderm gives rise to:

Answer 4

contributes to the cornea and forms the angioblasts of the choroid layer

Question 5

Location of the optic groove/sulcus

Answer 5

in the future diencephalic region of the prosencephalic neural groove

Question 6

optic sulcus –> ___ –> ____

Answer 6

optic vesicles, optic stalks

Question 7

Primordia of the lenses

Answer 7

Lens placodes

Question 8

How do lens vesicles form?

Answer 8

The lens placodes invaginate into the surface ectoderm, forming lens pits. The edges of the pits approach each other and fuse

Question 9

Where do retinal fissures develop

Answer 9

develop on the ventral surface of the optic cups and along the optic stalks

Question 10

Contents of retinal fissures and what they develop

Answer 10

The fissures contain vascular mesenchyme that will form the hyaloid blood vessels: the hyaloid artery and the hyaloid vein.

Question 11

What do hyaloid vessels become

Answer 11

proximal parts persist as the central artery and vein of the retina

Question 12

How does the lens receive nutrients

Answer 12

diffusion from the aqueous humor in the anterior chamber of the eye, which bathes its anterior surface, and from the vitreous humor in other parts

Question 13

Gelatinous matrix secreted by optic disc

Answer 13

Primary vitreous body

Question 14

Avascular mass of transparent, gel-like, intercellular substance.

Answer 14

Vitreous humor

Question 15

What is the tunica vasculosa lentis

Answer 15

Branches of the hyaloid artery extend over the lens

Question 16

Anterior part of the tunica vasculosa lentis

Answer 16

Pupillary membrane

Question 17

When does the pupil form

Answer 17

after the degeneration of the pupillary membrane

Question 18

How do the layers of the retina form

Answer 18

The two walls of the optic cup: the thick inner wall and the thin outer wall of the cup. Walls of the cup are continuous with the brain

Question 19

Cells of thick inner wall differentiate into

Answer 19

Neural retina

Question 20

Contents of neural retina

Answer 20

Photoreceptors (rods and cones) and the cell bodies of neurons

Question 21

The thin outer wall becomes the

Answer 21

cuboidal melanin-containing pigmented epithelium.

Question 22

How does the choroid develop

Answer 22

Differentiation of mesenchyme surrounding the optic cup (largely of neural crest origin) into an inner vascular layer

Question 23

How does the sclera develop

Answer 23

Differentiation of mesenchyme surrounding the optic cup (largely of neural crest origin) into an outer fibrous layer

Question 24

What forms the cilliary processes?

Answer 24

The choroid’s medial surface projects toward the lens, formed of capillaries supported by delicate connective tissue

Question 25

The smooth muscle of the ciliary body

Answer 25

Ciliary muscle

Question 26

What does the iris develop from

Answer 26

The rim of the optic cup, which grows inward and partially covers the lens

Question 27

The connective tissue of the iris is derived from

Answer 27

Neural crest cells

Question 28

The dilator pupillae and sphincter pupillae muscles of the iris are derived from

Answer 28

Neuroectoderm of the optic cup

Question 29

Cornea forms from three sources:

Answer 29

1. The external (anterior) corneal epithelium, derived from surface ectoderm

2, 3. Mesoderm and neural crest cells differentiate into the substantia propria of the cornea and the corneal endothelium.

Question 30

Eyelids form from:

Answer 30

neural crest cell mesenchyme and from two cutaneous folds of ectoderm that grow over the cornea.

Question 31

What forms as eyelids open

Answer 31

The bulbar conjunctiva and palpebral conjunctiva

Question 32

The eyelashes and glands in the eyelids are derived from

Answer 32

Surface ectoderm

Question 33

How do lacrimal glands form

Answer 33

The lacrimal glands develop from a number of solid buds from the surface ectoderm. The buds branch and become canalized to form the nasolacrimal ducts.