Embryology of the Eye

Question 1

Gives rise to the sensory retina *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 1

A. Neuroectoderm — The neural retina develops from neuroectoderm, part of the neural tube.

Question 2

Gives rise to the epithelium of the Zeis gland *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 2

B. Surface Ectoderm — The Zeis gland is a skin adnexal structure that comes from surface ectoderm.

Question 3

Gives rise to the epithelium of the Moll gland *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 3

B. Surface Ectoderm — The Moll gland is a modified sweat gland derived from surface ectoderm.

If gland itself, MESODERM

Question 4

Gives rise to the lacrimal gland passages *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 4

B. Surface Ectoderm — Lacrimal ducts are epithelial structures originating from surface ectoderm.

Question 5

Gives rise to the episclera *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 5

B. Surface ectoderm

Question 6

Gives rise to the sclera *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 6

C. Mesoderm

Question 7

Gives rise to Descemet’s membrane *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 7

D. Neural Crest Cells — Descemet’s membrane is secreted by corneal endothelium derived from neural crest.

Question 8

Gives rise to the corneal endothelium *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 8

D. Neural Crest Cells — The corneal endothelium originates from neural crest-derived mesenchyme.

Question 9

Gives rise to the crystalline lens *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 9

B. Surface Ectoderm — The lens develops from the lens placode, which is from surface ectoderm.

Question 10

Gives rise to the conjunctival epithelium *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 10

B. Surface Ectoderm — Conjunctival epithelium is an external epithelial structure from surface ectoderm.

Question 11

Gives rise to the corneal stroma *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 11

C. Mesoderm — The stroma (substantia propria) has mesenchymal origin, derived from mesoderm.

Question 12

Gives rise to the corneal epithelium *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 12

B. Surface Ectoderm — Corneal epithelium is a surface covering tissue from the surface ectoderm.

Question 13

Gives rise to Tenon’s capsule *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 13

C. Mesoderm

Question 14

Gives rise to the bones of the orbit *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 14

C. Mesoderm — Orbital bones arise from mesodermal mesenchyme.

Question 15

Gives rise to the non-pigmented epithelium of the ciliary body *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 15

A. Neuroectoderm — It’s continuous with the retina, hence derived from neuroectoderm.

Question 16

Gives rise to the muscles of the ciliary body *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 16

C. Mesoderm — Smooth muscles like the ciliary muscle come from mesoderm.

Question 17

Gives rise to the iris stroma *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 17

D. Neural Crest Cells — Iris stroma is mesenchymal in origin, derived from neural crest.

Question 18

Gives rise to the stroma of the ciliary body *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 18

D. Neural Crest Cells — Like iris stroma, this is from neural crest mesenchyme.

Question 19

Gives rise to the suspensory ligaments *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 19

C. Mesoderm — Suspensory (zonular) fibers are mesodermal connective tissue elements.

Question 20

Gives rise to the melanocytes *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 20

D. Neural Crest Cells — Melanocytes are pigment cells from neural crest.

Question 21

Gives rise to the nerve fibers of the optic nerve *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 21

A. Neuroectoderm — The optic nerve consists of retinal ganglion axons derived from neuroectoderm.

Question 22

Gives rise to the smooth muscle of the iris *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 22

A. Neuroectoderm — Iris muscles (dilator and sphincter) are unusual as they arise from neuroectoderm.

Question 23

Gives rise to the tarsal gland *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 23

C. Mesoderm — Meibomian (tarsal) glands form from mesoderm-derived mesenchyme.

Question 24

Gives rise to the eyelids *
A. Neuroectoderm
B. Surface Ectoderm
C. Mesoderm
D. Neural Crest Cells

Answer 24

B. Surface Ectoderm

Question 25

Gives rise to the choroid * A. Neuroectoderm B. Surface Ectoderm C. Mesoderm D. Neural Crest Cells

Answer 25

C. Mesoderm — The choroid is a vascular layer derived from mesodermal tissue.

Question 26

Gives rise to the Medial Rectus muscle * A. Neuroectoderm B. Surface Ectoderm C. Mesoderm D. Neural Crest Cells

Answer 26

C. Mesoderm — All extraocular muscles develop from mesoderm.

Question 27

Gives rise to the primary vitreous (choose 2) * A. Neuroectoderm B. Surface Ectoderm C. Mesoderm D. Neural Crest Cells

Answer 27

A & D. Neuroectoderm and Neural Crest Cells — The primary vitreous is formed by both these embryologic sources. Secondary Vitreous - mesenchyme

Question 28

Gives rise to the sphincter pupillae muscle * A. Neuroectoderm B. Surface Ectoderm C. Mesoderm D. Neural Crest Cells

Answer 28

A. Neuroectoderm — Like the dilator, sphincter muscle is from neuroectoderm.

Question 29

Gives rise to the optic nerve * A. Neuroectoderm B. Surface Ectoderm C. Mesoderm D. Neural Crest Cells

Answer 29

A. Neuroectoderm — The optic nerve consists of retinal ganglion axons derived from neuroectoderm.

Question 30

Gives rise to the optic nerve sheath (meninges) * A. Neuroectoderm B. Surface Ectoderm C. Mesoderm D. Neural Crest Cells

Answer 30

D. Neural Crest Cells — Meninges (covering of optic nerve) are from neural crest.

Question 31

Gives rise to the dilator pupillae muscle * A. Neuroectoderm B. Surface Ectoderm C. Mesoderm D. Neural Crest Cells

Answer 31

A. Neuroectoderm — Like sphincter muscle, it’s neuroectoderm-derived.

Question 32

Gives rise to the inferior oblique muscle * A. Neuroectoderm B. Surface Ectoderm C. Mesoderm D. Neural Crest Cells

Answer 32

C. Mesoderm — Extraocular muscles like the inferior oblique come from mesoderm.

Question 33

The part of the brain where the eye starts to emerge during embryogenesis * A. Diencephalon B. Midbrain C. Thalamus D. Cerebellum

Answer 33

A. Diencephalon — The optic vesicles form as evaginations of the diencephalon.

Question 34

What day during embryologic development does the eye start to develop? A. Day 22 B. Day 23 C. Day 25 D. Day 38

Answer 34

A. Day 22 — Eye development begins with formation of the optic grooves.

Question 35

What day do the optic pits appear on the neural tube? A. Day 22 B. Day 23 C. Day 25 D. Day 38

Answer 35

B. Day 23 — Optic pits appear as the first visible sign of optic development.

Question 36

What day do the optic vesicles appear? A. Day 22 B. Day 23 C. Day 25 D. Day 38

Answer 36

C. Day 25 — Optic vesicles are formed from the evagination of the optic pits.

Question 37

On which day does the embryonic fissure close? * A. Day 17 B. Day 23 C. Day 27 D. Day 33

Answer 37

D. Day 33 — Closure of the optic fissure completes globe formation. The optic pits first appear on day 23 of gestation. Evagination of the optic vesicle occurs on day 25 with induction of the lens on day 28. Closure of the optic fissure occurs on day 33. This closure allows pressurization of the globe. The optic fissure closes on approximately day 33 of gestation. It begins midway between the optic nerve and the iris and “zips up” in both anterior and posterior directions.

Question 38

On what week does the anterior chamber appear? A. Week 7 B. Week 14 C. Week 23 D. Week 36

Answer 38

A. Week 7 — The anterior chamber forms after regression of the pupillary membrane.

Question 39

On what month in vitro do the hyaloid arteries completely atrophy? A. 6th month B. 7th month C. 8th month D. 9th month

Answer 39

C. 8th month — The hyaloid system normally regresses by the 8th month.

Question 40

The retinal pigmented epithelium comes from the ________? A. Inner Cup B. Outer Cup

Answer 40

B. Outer Cup — The outer layer of the optic cup becomes the RPE.

Question 41

The neurosensory retina comes from the ________? A. Inner Cup B. Outer Cup

Answer 41

A. Inner Cup — The inner optic cup layer forms the neural retina.

Question 42

When light enters the eye, where does it first land? A. Inner Cup B. Outer Cup

Answer 42

A. Inner Cup — Light first interacts with the photoreceptors of the inner cup-derived retina.

Question 43

Mesoderm cells merge with the sclera to form what ocular structure? A. Conjunctival Epithelium B. EOM C. Corneal Endothelium D. Iris Epithelium

Answer 43

B. EOM — Extraocular muscles are derived from mesoderm.

Question 44

Part of the eye where remnants of the hyaloid artery drain after secondary vitreous is secreted? A. Cloquet's Canal B. Anterior Chamber C. Ora Serrata D. Posterior Chamber

Answer 44

A. Cloquet's Canal — This is the remnant path of the regressed hyaloid artery.

Question 45

Failure of the diencephalon to bulge out leads to: A. Aphakia B. Microphthalmos C. Anophthalmos D. Cataract

Answer 45

C. Anophthalmos — Without optic vesicle formation, no eye develops.

Question 46

Failure of the optic vesicle to invaginate results in: A. Congenital Cystic Eye B. Peter's Anomaly C. Congenital Retinal Non-Attachment D. Congenital Choroidal Enclosure

Answer 46

A. Congenital Cystic Eye — Occurs when invagination of the optic vesicle fails completely.

Question 47

Failure of surface ectoderm to invaginate results in: A. Aphakia B. Microphthalmos C. Anophthalmos D. Cataract

Answer 47

A. Aphakia — The lens fails to form due to lack of invagination.

Question 48

Failure of primary lens fibers to elongate results in: A. Aphakia B. Microphthalmos C. Anophthalmos D. Cataract

Answer 48

D. Cataract — Abnormal lens fiber arrangement leads to opacification.

Question 49

Failure of optic vesicle to invaginate completely results in: A. Congenital Cystic Eye B. Peter’s Anomaly C. Congenital Retinal Non-Attachment D. Congenital Choroidal Enclosure

Answer 49

C. Congenital Retinal Non-Attachment — Retina doesn’t fully form and attach.

Question 50

Failure of lens stalk to disintegrate leads to: A. Congenital Cystic Eye B. Peter’s Anomaly C. Congenital Retinal Non-Attachment D. Congenital Choroidal Enclosure

Answer 50

B. Peter’s Anomaly — Results in lens adhesion to the cornea via a persistent stalk.

Question 51

Mesoderm cells merge with the sclera to form what ocular structure? * A. Conjunctival Epithelium B. EOM C. Corneal Epithelium D. Iris Epithelium

Answer 51

B. EOM — Extraocular muscles are mesodermal in origin, integrating with the scleral development.

Question 52

Between the developing sclera and RPE, mesenchyme and vasculature combine to form: A. Choroid B. EOM C. Vitreous Humor D. Aqueous Humor

Answer 52

A. Choroid — Formed by mesenchymal tissue and vasculature between RPE and sclera.

Question 53

Part of the eye where the remnants of the hyaloid artery are drained: A. Cloquet's Canal B. Anterior Chamber C. Ora Serrata D. Posterior Chamber

Answer 53

A. Cloquet’s Canal — It contains remnants of the fetal hyaloid artery.

Question 54

This condition results from incomplete closure of the choroidal fissure: A. Persistent Hyaloid Artery B. Peter’s Anomaly C. Coloboma D. Congenital Choroidal Enclosure

Answer 54

C. Coloboma — It is due to failure of choroidal fissure to close, often affecting inferior iris.

Question 55

Distal hyaloid artery persists, impairing vision: A. Persistent Hyaloid Artery B. Peter’s Anomaly C. Coloboma D. Congenital Choroidal Enclosure

Answer 55

A. Persistent Hyaloid Artery — Should regress by 8th month; if not, causes obstruction in visual axis.

Question 56

Cornea is connected to anterior lens by a stalk due to pax6 mutation: A. Persistent Hyaloid Artery B. Peter’s Anomaly C. Coloboma D. Congenital Choroidal Enclosure

Answer 56

B. Peter’s Anomaly — A rare anterior segment dysgenesis where lens adheres to cornea.

Question 57

Neuroectoderm fails to fuse with surface ectoderm: A. Aphakia B. Microphthalmos C. Anophthalmos D. Peter’s Anomaly

Answer 57

B. Microphthalmos — Eye is smaller due to disrupted inductive signaling between layers.

Question 58

Responsible for transmitting nerve impulses to cortex: A. Central Retinal Vein B. Optic Nerve C. LGB D. Optic Radiation

Answer 58

B. Optic Nerve — It carries visual signals from retina to brain.

Question 59

All are true about retinal vessel development EXCEPT: A. Originate from mesenchymal tissue in week 16 B. Grow to nasal ora by 32 weeks C. Grow to temporal ora by 34 weeks D. Radiate centrifugally from optic nerve

Answer 59

C. Grow to temporal ora by 34 weeks — They usually reach temporal ora later (36–40 weeks).

Question 60

Which structure is affected in retinopathy of prematurity? A. Lens B. Cornea C. Retina D. Choroid E. Lids

Answer 60

C. Retina — Abnormal vascular development in premature infants leads to retinal detachment.

Question 61

Which structures can be affected in coloboma? (Select all that apply) A. Iris B. Choroid C. Retina D. Ciliary Body E. Optic Disc

Answer 61

A, B, C, E — Coloboma can affect iris, choroid, retina, and optic disc due to incomplete fissure closure.

Question 62

Failure of the neuroectoderm to fuse with the surface ectoderm * A. Aphakia B. Microphthalmos C. Anophthalmos D. Peter’s Anomaly

Answer 62

B. Microphthalmos — Incomplete fusion leads to a smaller eye (microphthalmos).

Question 63

Gives rise to the corneal endothelium * A. Neuroectoderm B. Surface Ectoderm C. Mesoderm D. Neural Crest Cells

Answer 63

D. Neural Crest Cells

Question 64

This is responsible for transporting nerve impulses to the cerebral cortex for processing: A. Central Retinal Vein B. Optic Nerve C. LGB D. Optic Radiation

Answer 64

B. Optic Nerve

Question 65

All of the following are true regarding the embryologic development of retinal vessels, except: A. originate from mesenchymal tissue during week 16 of gestation B. grow to nasal ora by 32 weeks gestation C. grow to temporal ora by 34 weeks gestation D. radiate centrifugally from optic nerve

Answer 65

C. grow to temporal ora by 34 weeks gestation Retinal vessels develop de novo from precursor mesenchymal tissue, beginning during gestational month 4. The vessels radiate outward from the optic nerve, reaching the nasal ora by week 32 and the temporal ora approximately 1 to 2 months later.

Question 66

Which of the following structures of the eye can be affected in coloboma? Select all that apply: Iris Choroid Retina Ciliary body Optic disc

Answer 66

All except ciliary body