Discussion about the Histology of Cornea & Retina

1. Dr Rajiv Ranjan
RIMS, Ranchi
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2. Introduction
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3. Cornea
Layers :
I. external stratified squamous epithelium;
II. anterior limiting membrane (Bowman’s
membrane),
III. The thick stroma;
IV. posterior limiting membrane (Descemet’s
membrane),
V. inner simple squamous endothelium.
Thick, Transparent, Avascular
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4. External stratified layer
Lining : 5 to 6 cell layers thick
10% of the corneal Thickness
Basal cells : progenitor cell
Apical cells : flattened cells c̄ microvilli
bathing in tear film
Bowman’s membrane  Ant. Limiting membrane
thick basement membrane (8-10 μm)
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5. Internal squamous layer
 Descemet’s membrane  Post. limiting
membrane
 basement membrane of the endothelium
Thick stroma
(substantia propria)
~ 90% of thickness
Keratocytes
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6. Cornea
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7. Applied
• Corneal transplants
• LASIK
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8. Retina
Human have inverted retina
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9. Development of Retina
I. Outer pigmented layer; a simple cuboidal epithelium attached to Bruch’s membrane & the choroid
II. Inner neural layer, is thick and stratified with various neurons and photoreceptors.
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10. Retina Pigmented Epithelium
• Abundant smooth ER (SER) specialized for
retinal (vitamin A) isomerization
• Absorbs scattered light
• Blood-retina barrier
• Retinal regeneration (isomerize all-trans-
retinal released from photoreceptors and
produce 11-cis-retinal)
• Phagocytosis
• Remove free radicals
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11. Neural Retina
• Possesses 3 major layers of nuclei and their
interconnected neurons exhibiting nine distinct
layers
I. Outer nuclear layer (ONL) contains cell bodies of
photoreceptors (the rod and cone cells).
II. Inner nuclear layer (INL) contains the nuclei of
various neurons, notably the bipolar cells,
amacrine cells and horizontal cell.
III. Ganglionic layer (GL) has neurons (ganglion
cells) with much longer axons. These axons make
up the nerve fiber layer (NFL) and converge to
form the optic nerve
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12. Rods & Cones
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13. Neural synapses
• Between the 3 layers with cell nuclei are 2
fibrous or “plexiform” regions containing only
axons and dendrites connected by synapses
I. Outer plexiform layer (OPL) includes axons
of the photoreceptors and dendrites of
association neurons in the INL.
II. The inner plexiform layer (IPL) consists of
axons and dendrites connecting neurons of
the INL with the ganglion cells
• All neurons of the retina are supported
physically by glial cells called müller cells; with
their nuclei in the INL; form the limiting
membranes
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14. Layers of Retina
I. The inner limiting layer (ILL) terminal expansions of Müller
cell processes that cover the collagenous membrane of the
vitreous body.
II. The nerve fiber layer (NFL) containing the ganglionic cell
axons that converge at the optic disc and form the optic nerve
III. The ganglionic layer (GL) containing cell bodies of the
ganglion cells
IV. The inner plexiform layer (IPL) containing fibers and synapses
of the ganglion cells and the bipolar neurons.
V. The inner nuclear layer (INL) with the cell bodies of several
types of bipolar neurons.
VI. The outer plexiform layer (OPL) containing fibers and
synapses of the bipolar neurons and rod and cone cells
VII. The outer nuclear layer (ONL) cell bodies of the rod and cone.
VIII. The outer limiting layer (OLL) line formed by junctional
complexes holding the rod and cone cells to the intervening
Müller cells
IX. The rod and cone layer (RCL) the outer photoreceptors seg.
X. The non-neural pigmented layer (PL)
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15. Layers of Retina
I. The inner limiting layer (ILL)
II. The nerve fiber layer (NFL)
III.The ganglionic layer (GL)
IV.The inner plexiform layer (IPL)
V. The inner nuclear layer (INL)
VI.The outer plexiform layer (OPL)
VII.The outer nuclear layer (ONL)
VIII.The outer limiting layer (OLL)
IX.The rod and cone layer (RCL)
X. The non-neural pigmented cell layer (PL)
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16. Retinal Detachment
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