Embryology of the EyeEmbryology of the Eye

Lens Placode

AView B

Mandibular Arch

Prosencephalon

Neuroepithelium

Optic Vesicle

B

[diencephalon]

Med 6573: Nervous SystemUniversity of Minnesota Medical School Duluth

Donna J. Forbes, Ph.D.29 February 2008

References

Moore & Persaud, Chapter 19, pages 492 - 503

Nolte: Chapter 17, pages 411 - 412

Dr. Downing’s “Histology of the Eye”

Learning Objectives• Optic Cup: Relationship to diencephalon &

to lens placode during development• Origin and Formation of the:

– Optic Nerve & Retina– Iris & Ciliary Body– Lens– Choroid, Sclera & Cornea

• Inductive influences involved in the development of the eye.

• Congenital malformations of the eye

Critical Period for Development of the Eyes

Middle of Week 4 to Middle of Week 8, but continues to birth

Neuroectoderm of the Prosencephalon

(Diencephalon)

Optic Grooves

Optic Vesicles

Optic Cups

[AKA Neuroectoderm]

Prosencephalon

Neuroepithelium

Lens Placode

Optic Vesicle

Mandibular Arch

[diencephalon]

• Retina• Optic Nerve• Ciliary Body• Iris

M & P 19 - 1

≈22 days

≈28 days

≈32 days

Eye DevelopmentOptic Grooves

Optic Vesicles

Optic Cups

Prosencephalon

Neuroepithelium

Lens Placode

Optic Vesicle

Mandibular Arch

[diencephalon]

M & P 19 - 1

≈22 days

≈28 days

≈32 days

Eye DevelopmentOptic Nerve, Optic or

Choroid Fissure & Lens

Prosencephalon

Neuroepithelium

Lens Placode

Optic Vesicle

Mandibular Arch

[diencephalon]

M & P 19 - 1

≈22 days

≈28 days

≈32 days

Next slide

Eye DevelopmentOptic Nerve & Optic or Choroid Fissure cont.

Prosencephalon

Neuroepithelium

Lens Placode

Optic Vesicle

Mandibular Arch

[diencephalon]

M & P 19 - 3

Closure of the Optic Fissure & Formation of the Optic Nerve

Edges of the pupil

• Optic Fissure

• Pupil

• Hyaloid vessels

• Optic Nerve (ON)

• Sheath of ON

M & P 19 - 8

Retina, Ciliary Body, Iris, Lens

Mesenchyme

The following slides look at each of these derivatives.

Retina: forms from the two layers of the optic cup

Note: Intraretinal space is eliminated by fusion of the pigment layer with the neural layer of the retina.

Developing pigment epithelium of the retina [from outer layer of optic cup]

Developing neural layer of the retina [from inner layer of

optic cup]

Neural layer of the retina

Central artery of

retina

Intraretinal space

Pigment epithelium of

the retina

A B

C D

Mesenchyme

Ora serrata located about here

• Outer layer of optic cup >> pigment layer of retina

• Inner layer of optic cup >> neural layer of retina.

• Intraretinal Space

• Ora Serrata = junction of neural retina with ciliary body.

• Hyaloid artery & vein >> Central artery & vein of retina.

Hyaloid artery of

retina

3.5 wks 4 wks 5 wks

6 wks 6.5 wks 8 wks

Retina

Neural layer of the retina

Pigment epithelium layer of the

retina

Optic Vesicle

Intraretinal space

Lens Vesicle

Lens Lens

Lens Pit

Lens

Mesenchyme

Diencephalon

Inner layer of optic cup

Outer layer of optic cup

Optic Cup

Ciliary Body

Central artery of retina

A B

C D

Lens

Lens

Lens

LensIris

Ciliary Body & Iris

Mesenchyme

Ora serrata located about here

Iris

NEXT SLIDE

Develop from the inner & outer layers of the optic cup -- anterior to the ora serrata.

From mesenchyme

mesenchyme

Primary (posterior) lens fibers

Anterior lens fibers

Anterior chamber

Posterior chamber

Ciliary epithelium

[pigmented & non-pigmented

Ciliary Body [= processes + muscle]

• Pigmented & non-pigmented layers of ciliary epithelium that cover the ciliary processes develop from the outer & inner layers, respectively, of the optic cup.

• Ciliary muscle (smooth muscle) develops from surrounding mesenchyme.

Iris

From neuroectoderm

mesenchyme

Primary (posterior) lens fibers

Anterior lens fibers

Anterior chamber

Posterior chamber

STROMAL LAYER OF IRIS

• Epithelial layer forms from the most rostral aspect of optic cup; 2 cell layers thick; posterior side of iris; blue pigment

• Stromal or connective tissue layer forms from mesenchyme; anterior side of iris; brown pigment

• Sphincter & Dilator muscles of the pupil develop within the stromal layer of the iris from neuroectoderm of the optic cup.

3.5 wks 4 wks 5 wks

6 wks 6.5 wks 8 wks

Differentiation of the Lens

Lens

Lens Pit

Lens

Anterior layer of

the Lens

Posteriorlayer of

the Lens

Lumen within the

Lens Vesicle

Mesenchyme

Optic VesicleDiencephalon

Area of the Lens

Placode

Note that lumen

disappears

Remnants of hyaloid vessels

Vitreous body

Central artery of retina

Hyaloid canal

Irido-pupillary membrane

Irido-pupillary membrane

Posterior chamber

Posterior chamber

Future Anterior chamber Anterior

chamber

Anterior chamber

Mesenchyme

Aqueous Chambers & Vitreous Body

Hyaloid artery

[aqueous humor]

[aqueous humor]

[aqueous humor]

[aqueous humor]

Vascular plexus of the choroid

layer

Sclera

Mesenchyme

Choroid & Sclera

Sheath of the optic nerve

• Choroid and Sclera form from surrounding mesenchyme.

• Inner layer is the vascular & pigmented CHOROID. Comparable to pia-arachnoid.

• Outer layer is the tough SCLERA. Comparable to dura. Continuous with the sheath of the optic nerve, posteriorly.

Epithelium

Mesenchyme Surface Ectoderm

Cornea & Conjunctiva3 layers of the

cornea

Stroma

Endothelium

Three layers of the cornea & conjunctiva form at the most anterior aspect of the eye.

• SURFACE ECTODERM induced by lens to form the EPITHELIUM of the cornea & conjunctivum.

• STROMA is derived from mesenchyme.

• ENDOTHELIUM forms from the mesenchymal lining of the anteior chamber.

Epithelium

Stroma

Endothelium

Cornea

Eyelids

Eyelids fused by Wk 10

Mesenchyme

Surface Ectoderm

Eyelids re-opened by ~26 wks.

Transverse folds of surface ectoderm + mesenchyme begin to form in Week 6.

Muscles & Nerves of the Eyelids: Skeletal muscle

Orbicularis oculi (2nd arch; facial, SVE)

Levator palpebrae superioris (pre-otic myotomes; oculomotor, GSE)

Smooth muscle

Superior tarsal (mesenchyme; sympathetics, GVE)

Congenital Cataract

Balloon-Like Congenital Cataract

Congenital Familial Central Cataract

Etiologies:• Rubella infection of mom at 4 - 7 wks gestation• Hereditary• Malnutrition• Chromosomal abnormalities• Radiation• Galactosemia

Lens becomes opaque during intrauterine life.

Detached Retina

• Disruption of the adhesion between the neural and pigmented layers of the retina.

• These examples in the adult.

• During development, congenital detached retina appears to be: • due to failure of the retinal layers to fuse and obliterate the intraretinal space.• caused by unequal growth of the eye.

Iris of right eye

Retina

Iris of right eye

Congenital Ptosis

A. Disturbed development of the levator palpebrae superioris and/or its oculomotor (GSE) innervation.

B. Surgically corrected

C. Autosomal dominant trait

Iris of right eye

Retina

Iris of right eye

A B

Congenital Coloboma

• Defective closure of the choroid or optic fissure• Position: infero-nasal quadrant reflective of the

location of the optic fissure during development

Iris of right eye

Iris of right eye

Iris of right eye

Retina of right eye