The development of the eyes begins with the formation of optic vesicles from outpocketings of the forebrain during the 22-day embryo stage. The optic vesicles invaginate to form double-walled optic cups. During the fifth week, lens placodes form and invaginate to become lens vesicles that develop inside the optic cups. By the seventh week, the lips of the choroid fissure have fused and the mouth of the optic cup has formed into the future pupil, while the lens vesicle has lost contact with the surface ectoderm. Later stages involve differentiation of the optic cup layers into the retina, iris, and ciliary body and surrounding tissues such as the choroid, sclera, cor

1. DEVELOPMENT OF THE EYES
Jimale Mohamed Ali

2. Optic Cup and Lens Vesicle
• The developing eye appears in the 22-day embryo as a pair of
shallow grooves on the sides of the forebrain.
• When neural tube is closed, these grooves form outpocketings
of the forebrain, the optic vesicles.
• The optic vesicle begins to invaginate and forms the double-
walled optic cup.
• The inner and outer layers of this cup are initially separated
by a lumen, the intraretinal space.
• This lumen disappears, and the two layers appose each other.

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• Invagination is not restricted to the central portion of the cup
but also involves a part of the inferior surface that forms the
choroid fissure.
• Formation of this fissure allows the hyaloid artery to reach the
inner chamber of the eye.
Optic
vescicle
Optic
vescicle

4. • During the seventh week,
• The lips of the choroid fissure fuse,
• The mouth of the optic cup becomes a round opening, the
future pupil.
• The cells of the surface ectoderm begin to elongate and form
the lens placode.
• This placode subsequently invaginates and develops into the
lens vesicle.
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5. Continue
• During the fifth week, the lens vesicle loses contact with the
surface ectoderm and lies in the mouth of the optic cup.
Sixth week Seventh week Ninth week

6. Retina, Iris, and Ciliary Body
• The outer layer of the optic cup is known as the pigmented
layer of the retina.
• Development of the inner (neural) layer of the optic cup is
more complicated. The posterior four-fifths, the pars optica
retinae, contains cells bordering the intraretinal space that
differentiate into light-receptive elements, rods and cones.
• Adjacent to this photoreceptive layer is the mantle layer,
which, as in the brain, gives rise to neurons and supporting
cells, including the outer nuclear layer, inner nuclear layer, and
ganglion cell layer.

7. • The optic stalk develops into the optic nerve.
• The anterior fifth of the inner layer, the pars ceca retinae,
remains one cell layer thick.
• It later divides into the pars iridica retinae, which forms the
inner layer of the iris, and the pars ciliaris retinae, which
participates in formation of the ciliary body.
• The region between the optic cup and the overlying surface
epithelium is filled with loose mesenchyme.
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8. • The sphincter and dilator pupillae muscles form in this tissue.
• These muscles develop from the underlying ectoderm of the
optic cup.
• In the adult, the iris is formed by the pigment-containing
external layer, the unpigmented internal layer of the optic cup,
and a layer of richly vascularized connective tissue that
contains the pupillary muscles.
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9. • The pars ciliaris retinae is easily recognized by its marked
folding.
• Externally it is covered by a layer of mesenchyme that forms
the ciliary muscle; on the inside it is connected to the lens by a
network of elastic fibers, the suspensory ligament or zonula.
• Contraction of the ciliary muscle changes tension in the
ligament and controls curvature of the lens.
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10. Development of the iris and ciliary body

11. Lens
• Shortly after formation of the lens vesicle, cells of the
posterior wall begin to elongate anteriorly and form long fibers
that gradually fill the lumen of the vesicle.
• By the end of the 7th week, these primary lens fibers reach the
anterior wall of the lens vesicle.
• Growth of the lens is not finished at this stage.
• New (secondary) lens fibers are continuously added to the
central core.

12. Choroid, Sclera, and Cornea
• At the end of the 5th week,
• The eye primordium is completely surrounded by loose
mesenchyme.
• This tissue soon differentiates into an inner layer comparable
with the pia mater of the brain and an outer layer comparable
with the dura mater.
• The inner layer later forms a highly vascularized pigmented
layer known as the choroid.
• The outer layer develops into the sclera and is continuous with
the dura mater around the optic nerve.

13. • Differentiation of mesenchymal layers overlying the anterior
aspect of the eye is different.
• The anterior chamber forms through vacuolization and splits
the mesenchyme into.
• Inner layer in front of the lens and iris, the iridopupillary
membrane.
• Outer layer continuous with the sclera, the substantia propria
of the cornea.
• The anterior chamber itself is lined by flattened mesenchymal
cells.
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14. Continue
• The cornea is formed by;
1. An epithelial layer derived from the surface ectoderm.
2. The substantia propria or stroma, which is continuous
with the sclera.
3. An epithelial layer, which borders the anterior chamber.
• The iridopupillary membrane in front of the lens
disappears completely, providing communication between
the anterior and posterior eye chambers.

15. Vitreous Body
• Mesenchyme not only surrounds the eye primordium from the
outside but also invades the inside of the optic cup by way of
the choroid fissure.
• Here it forms the hyaloid vessels, which during intrauterine
life supply the lens and form the vascular layer on the inner
surface of the retina.
• In addition, it forms a delicate network of fibers between the
lens and retina.
• The interstitial spaces of this network later fill with a
transparent gelatinous substance, forming the vitreous body.
• The hyaloid vessels in this region are obliterated and
disappear during fetal life, leaving behind the hyaloid canal.

16. Optic Nerve
• The optic cup is connected to the brain by the optic stalk,
which has a groove, the choroid fissure, on its ventral surface.
• The nerve fibers of the retina returning to the brain lie among
cells of the inner wall of the stalk.
• During the seventh week, the choroid fissure closes, and a
narrow tunnel forms inside the optic stalk.
• Increasing the number of nerve fibers, the inner wall of the
stalk grows, and the inside and outside walls of the stalk fuse.

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• Cells of the inner layer provide a network of neuroglia that
support the optic nerve fibers.
• The optic stalk is transformed into the optic nerve, and its
center contains a portion of the hyaloid artery, later called the
central artery of the retina.
• On the outside, a continuation of the choroid and sclera, the
pia arachnoid and dura layer of the nerve, respectively,
surround the optic nerve.

18. Eye of a fifteen week old fetus

19. Eye Anomalies
1. Coloboma iridis may occur if the choroid fissure fails to close.
• Coloboma is a common eye abnormality frequently associated with
other eye defects.
• Colobomas (clefts) of the eyelids may also occur.
2. The iridopupillary membrane may persist instead of being
resorbed during formation of the anterior chamber.
3. Congenital cataracts: the lens becomes opaque during
intrauterine life.
• This anomaly is usually genetic, but many children of mothers with
Rubella between 4th and 7th weeks of pregnancy have cataracts.
• If the mother is infected after the 7th week of pregnancy, the lens
escapes this damage, but the may be deaf due to abnormalities of the
cochlea.

20. Eye Anomalies
B. Persistence of the
iridopupillary membrane.
A. Coloboma iris.

21. • The hyaloid artery may persist to form a cord or cyst.
• microphthalmia the eye is too small.
• Anophthalmia is absence of the eye.
• Congenital aphakia: absence of the lens, and Aniridia:
absence of the iris are rare anomalies.
• Cyclopia (single eye) and synophthalmia (fusion of the
eyes).
• Blue sclera: (thin sclera through which the pigment of
choroid can be seen).
• Anomalies of pigmentation/ albinism.
Eye Abnormalities

22. Part Derived from
Lens Surface ectoderm
Retina Neuroectoderm (optic cup)
Vitreous Mesoderm
Choroid Mesoderm (infiltrated by neural crest cells?)
Ciliary body Mesoderm
Ciliary muscles Mesenchymal cells covering the developing ciliary body (neural
crest)
Iris Mesoderm
Muscles of the iris Neuroectoderm (from optic cup)
Sclera Mesoderm (infiltrated by neural crest cells?)
Cornea Surface epithelium by ectoderm, substantia propria and inner
epithelium by neural crest
Conjunctiva Surface ectoderm
Blood vessels mesoderm
Optic nerve Neuroectoderm. Its covering (pia, arachnoid and dura) are derived
from mesoderm
Summary of parts of the eye ball

23. Then?
Thanks for your attention!!