Development of pituitary gland and eye

1. DEVELOPMENT OF PITUITARY GLAND
&
EYE
DR NEETA CHHABRA

2. Pituitary Gland
• 2 parts, which differ embryologically,
structurally & functionally
• Anterior Pituitary (Adenohypophysis)
Has “Endocrine” Cells
• Posterior Pituitary (Neurohypophysis)
Has nerve fibers and pituicytes
Cell bodies are in hypothalamus

3. Development of Pituitary gland
• Is from surface ectoderm &
neuro ectoderm
• Anterior pituitary : From
Rathke’s pouch that arises
from ectoderm of stomodeum
• Posterior pituitary : From
evagination of the floor of 3rd
ventricle (diencephalon)

4. Development of Pituitary

5. Clinical Anatomy
• Pituitary agenesis/hypoplasia
• Pharyngeal hypophysis
• Craniopharyngiomas

6. Development of Eye
• Begins at 3rdweek and continues through the
tenth week
• Cells from both the ectodermal & mesodermal
tissues contribute to the formation of eye
• Ectoderm : Neuro ectoderm
Surface ectoderm
• Mesoderm : Extracellular mesenchyme which
consists of both, the neural crest cells and
mesoderm
• Endoderm does not take part in formation of Eye

7. Formation of Optic vesicle
• At 22nd day of IUL, neural plate destined
to form prosencephalon shows
thickened area on each side that
becomes depressed to form Optic sulcus
• Optic sulcus bulges outwards to form
Optic vesicle
• Proximal part of optic vesicle becomes
constricted and elongated to from Optic
stalk

8. Formation of Lens vesicle
• As the optic vesicle comes in contact with
surface ectoderm, it thickens : Lens
placode
• Lens placode depresses to form Lens pit &
later, Lens vesicle
• Lens vesicle loses contact with surface
ectoderm by 33rd day

9. Formation of Optic cup
• Optic vesicle is converted into a double
layered structure : Optic cup
• This is due to differential growth of the
walls of the optic vesicle
• The optic cup grows over the upper &
lateral side of lens & not on the inferior
aspect leading to a gap : Choroidal
fissure or fetal fissure

10. Changes in Associated Mesoderm
• Developing neural tube is
surrounded by mesoderm, that
differentiates to form:
Superficial fibrous layer : Dura mater
Deeper vascular layer : Pia-arachnoid
• This mesoderm covers optic vesicle
also

11. Mesenchyme
• A part of this mesoderm along with
blood vessels is carried into the optic
cup through choroidal fissure: hyaloid
vessels
• Distal part of vessels degenerate,
proximal part form central artery &
vein of retina
Changes in Associated Mesoderm

12. • Lens vesicle: Lined by a single layer of cuboidal
cells
• Cells of ant wall remain cuboidal: Epithelium
• Cells of post wall elongate, become columnar &
obliterate the cavity of the lens vesicle
• They lose their nuclei & form primary lens
fibers
• New lens fibers are formed from equatorial
cells of anterior part which later become hard
& form secondary lens fibers & lens grows
Development of Lens

13. Development of Retina
• Develops from optic cup : Neuroectoderm
• Optic cup has 2 parts: Anterior & Posterior
• Anterior part : Thin, forms ciliary & iridial
parts of retina
• Posterior part : Thick, forms various layers
of retina. It has has 2 walls
• Outer wall: Pigmented layer of retina
• Inner wall : Nervous layer of retina

14. Retina & Optic Nerve
• Inner wall: differentiates into 3 layers
• Matrix layer : Forms rods and cones
• Mantle layer: Forms bipolar cells,
ganglionic cells, other neurons &
supporting tissue
• Marginal layer: Axons of ganglion
cells converge towards optic stalk &
forms Optic Nerve

15. • During embryonic & early foetal life,
pigment & neural layers of retina are
separated by intra retinal space which
represents the original cavity of the optic
cup
• Before birth this space is obliterated due
to proliferation of cells of inner layer
• Thus, rod & cone cells come in contact
with pigment layer of retina
Development of Retina

16. Sclera and Choroid
• During 6th or 7th week of IUL mesenchyme
surrounding external surface of optic cup
condenses into two layers:
Outer fibrous layer: Sclera
Inner vascular layer : Choroid
• Sclera is continuous anteriorly with
substantia propria of cornea & posteriorly
with dura mater
• Choroid is continuous anteriorly with ciliary
body & iris & posteriorly with pia arachnoid

17. Ciliary Body
• Derived from forward prolongation of
mesoderm forming the choroid
• Epithelium : Two layers of Optic cup
Outer pigmented layer : Pigmented layer
of optic cup
Inner non pigmented layer : Neural layer of
optic cup
• Stroma, ciliary muscle & blood vessels :
Vascular mesoderm

18. Iris
• Derived from forward prolongation of
mesoderm forming the choroid
• Epithelium : Two layers of Optic cup
Outer pigmented layer : Pigmented layer of
optic cup
Inner non pigmented layer : Neural layer of
optic cup
• Stroma & blood vessels : Vascular mesoderm
• Muscles : Neuroectodermal cells of optic cup

19. Cornea
• Cornea consists of 5 layers
• Outer Stratified squamous epithelium :
Surface ectoderm
• Bowman’s membrane & Lamina propria:
Mesoderm
• Descemet’s membrane & inner corneal
epithelium: Neural crest cells

20. Anterior & Posterior Chambers of Eye
• Anterior chamber : Splitting of Mesoderm
between iris & cornea
• Posterior chamber : Splitting of Mesoderm
between iris & lens
• Filled with aqueous humour secreted by
ciliary processes of ciliary body
• Communicate with each other after
disappearance of pupillary membrane
• Aqueous humour is drained by canal of
Schlemm

21. Vitreous
• Vitreous develops as follows:
• Primary vitreous develops from mesoderm
It is vascular having hyaloid vessels
• Secondary vitreous is secreted by
neuroectoderm of optic cup. It is avascular
• Secondary vitreous replaces the primary
vitreous

22. Eyelids
• Develop from reduplication of surface
ectoderm
• Muscles & tarsal plates : Mesoderm
• Folds grow & fuse with each other
• Space enclosed within folds : Conjunctival
sac
• Conjunctiva : Ectodermal origin
• Eyelids remain fused till 7 month of IUL

23. Lacrimal Apparatus
• Lacrimal Gland: Develops from 15 to 20
buds from the superolateral angle of
conjunctival sac
• Lacrimal sac & Nasolacrimal duct:
Develop from ectoderm of Nasolacrimal
furrow
• Lacrimal canaliculi develop from
canalization of ectodermal buds that
grow from medial ends of each eyelid into
lacrimal sac

24. Extraocular Muscles
Mesenchymal condensation
(Pre occipital myotomes)

25. Anomalies of Eye
1. Anophthalmia
2. Microphthalmia
3. Synophthalmia
4. Cyclopia
5. Proboscis

26. Anomalies of Lid & Lens
1. Entropion
2. Ectropion
3. Coloboma of eyelid
4. Epicanthus
5. Aphakia
6. Congenital Cataract
7. Coloboma of iris

27. Summary
Part Source
Sclera Mesoderm
Choroid Mesoderm
Retina Neuroectoderm (Optic cup)
Lens Surface ectoderm
Vitreous Primary (Mesoderm)
Secondary (Neuroectoderm)
Ciliary body Mesoderm
Epithelium : Optic cup (Neuroectoderm)
Ciliary muscle Mesoderm
Iris Mesoderm
Epithelium : Optic cup (Neuroectoderm)
Sphincter & dilator pupillae Neuroectoderm ( Optic cup)
Cornea Surface epithelium (Ectoderm
Rest of the layers (Mesoderm)
Conjunctiva Surface ectoderm
Optic nerve Neuroectoderm
Coverings (Mesoderm)

28. THANKS