Histology of the Eye
undefinedHistology of the Eye
Objectives
B
y
t
h
e
e
n
d
o
f
t
h
i
s
l
e
c
t
u
r
e
,
t
h
e
s
t
u
d
e
n
t
s
h
o
u
l
d
b
e
a
b
l
e
t
o
d
e
s
c
r
i
b
e
:
–
The general structure of the eye.
–
The microscopic structure of:
»
Cornea.
»
Retina.
EYE BULB
Three coats
Three coats
(3 Tunics):
(3 Tunics):
1
1
-
-
F
F
i
i
b
b
r
r
o
o
u
u
s
s
t
t
u
u
n
n
i
i
c
c
:
:
Cornea.
Cornea.
Sclera.
Sclera.
2
2
-
-
V
V
a
a
s
s
c
c
u
u
l
l
a
a
r
r
t
t
u
u
n
n
i
i
c
c
:
:
Choroid.
Choroid.
Ciliary body.
Ciliary body.
Iris.
Iris.
3
3
-
-
N
N
e
e
u
u
r
r
a
a
l
l
t
t
u
u
n
n
i
i
c
c
:
:
R
R
e
e
t
t
i
i
n
n
a
a
.
.
CORNEA
It is the transparent,
avascular and highly
innervated anterior portion
of the fibrous coat.
It is composed of 5 distinct
layers:
1. Corneal epithelium.
2. Bowman’s membrane.
3. Stroma.
4. Descemet’s membrane.
5. Corneal endothelium.
CORNEA (Cont.)
C
C
o
o
r
r
n
n
e
e
a
a
l
l
e
e
p
p
i
i
t
t
h
h
e
e
l
l
i
i
u
u
m
m
:
:
–
Non-keratinized Stratified
Non-keratinized Stratified
squamous epithelium.
squamous epithelium.
–
Contains numerous free nerve
Contains numerous free nerve
endings.
endings.
B
B
o
o
w
w
m
m
a
a
n
n
’
’
s
s
m
m
e
e
m
m
b
b
r
r
a
a
n
n
e
e
:
:
–
It is homogenous non-cellular
It is homogenous non-cellular
layer containing type I collagen
layer containing type I collagen
fibrils.
fibrils.
CORNEA (Cont.)
S
S
t
t
r
r
o
o
m
m
a
a
:
:
–
It is the thickest layer (about
It is the thickest layer (about
90%).
90%).
–
It is composed of parallel
It is composed of parallel
lamellae of dense collagenous
lamellae of dense collagenous
C.T.
C.T.
–
Each lamella is composed
Each lamella is composed
mainly of parallel type I
mainly of parallel type I
collagen fibers with long
collagen fibers with long
fibroblasts.
fibroblasts.
CORNEA (Cont.)
D
D
e
e
s
s
c
c
e
e
m
m
e
e
t
t
’
’
s
s
m
m
e
e
m
m
b
b
r
r
a
a
n
n
e
e
:
:
–
It is a thick basement membrane.
It is a thick basement membrane.
C
C
o
o
r
r
n
n
e
e
a
a
l
l
e
e
n
n
d
d
o
o
t
t
h
h
e
e
l
l
i
i
u
u
m
m
:
:
–
It is s simple squamous epithelium.
It is s simple squamous epithelium.
–
F
F
u
u
n
n
c
c
t
t
i
i
o
o
n
n
s
s
:
:
1- Formation of Descemet’s membrane.
1- Formation of Descemet’s membrane.
2- Keeping the stroma relatively dehydrated
2- Keeping the stroma relatively dehydrated
(sod. pump → water withdrawal from the stroma).
(sod. pump → water withdrawal from the stroma).
LIMBUS
(CORNEO SCLERAL JUNCTION)
It is the transition region between
the cornea and sclera.
It is about 1.5 mm width.
It is highly vascular.
It contains:
1.
Trabecular meshwork:
Endothelium-lined spaces. It
leads to canal of Schlemm.
2.
Canal of Schlemm:
It drains the aqueous humor
into the venous system.
C
a
n
a
l
o
f
S
c
h
l
e
m
m
Sclera
Cornea
Iris
Ciliary
body
Lens
SCLERA
It covers the posterior 5/6 of
It covers the posterior 5/6 of
the fibrous tunic.
the fibrous tunic.
S
S
c
c
l
l
e
e
r
r
a
a
P
P
r
r
o
o
p
p
e
e
r
r
:
:
c
c
o
o
n
n
s
s
i
i
s
s
t
t
s
s
o
o
f
f
i
i
n
n
t
t
e
e
r
r
l
l
a
a
c
c
i
i
n
n
g
g
b
b
u
u
n
n
d
d
l
l
e
e
s
s
o
o
f
f
t
t
y
y
p
p
e
e
I
I
c
c
o
o
l
l
l
l
a
a
g
g
e
e
n
n
(dense collagenous C.T.,
(dense collagenous C.T.,
irregular type).
irregular type).
Melanocytes are located in
Melanocytes are located in
the deeper regions.
the deeper regions.
CHOROID
It is the vascular, pigmented
It is the vascular, pigmented
posterior portion of the middle
posterior portion of the middle
vascular tunic.
vascular tunic.
S
S
t
t
r
r
u
u
c
c
t
t
u
u
r
r
e
e
:
:
It is composed mainly of
It is composed mainly of
loose C.T. with melanocytes.
loose C.T. with melanocytes.
It is separated from the retina
It is separated from the retina
by its Bruch’s membrane.
by its Bruch’s membrane.
CILIARY BODY
It is the anterior continuation of
It is the anterior continuation of
the choroid. It surrounds the
the choroid. It surrounds the
lens.
lens.
S
S
t
t
r
r
u
u
c
c
t
t
u
u
r
r
e
e
:
:
–
It is formed of loose vascular and
It is formed of loose vascular and
pigmented C.T. that contains 3
pigmented C.T. that contains 3
bundles of smooth muscle cells
bundles of smooth muscle cells
(ciliary muscle).
(ciliary muscle).
–
Its inner surface is lined by pars
Its inner surface is lined by pars
ciliaris retinae ( 2 rows of columnar
ciliaris retinae ( 2 rows of columnar
cells; outer pigmented and inner
cells; outer pigmented and inner
non- pigmented layers) .
non- pigmented layers) .
–
Its inner surface is highly folded
Its inner surface is highly folded
forming the ciliary processes.
forming the ciliary processes.
CILIARY PROCESSES
Processes project from
the inner surface of the
anterior 1/3 of the ciliary
body towards the lens.
Are covered by pars
ciliaris retinae (2 rows of
columnar cells).
They give attachment to
the lens suspensory
ligaments (zonule
fibers).
IRIS
I
t
i
s
f
o
r
m
e
d
o
f
5
l
a
y
e
r
s
:
1- Anterior border layer:
Incomplete layer of fibroblasts
and melanocytes.
2- Stroma:
Poorly vascularized C.T. with
fibroblasts and melanocytes.
3- Vessel layer:
Well-vascularized loose C.T.
Centrally, it contains circularly
arranged smooth muscle fibers
(sphincter pupillae muscle).
S
t
r
o
m
a
IRIS
4- Dilator pupillae muscle
4- Dilator pupillae muscle
layer:
layer:
Contains radially arranged
Contains radially arranged
myoepithelial cells.
myoepithelial cells.
5- Posterior surface layer
5- Posterior surface layer
(pigmented epithelium
(pigmented epithelium
layer):
layer):
It is composed of 2 rows of
It is composed of 2 rows of
pigmented
pigmented
epithelial cells
epithelial cells
(pars iridis retinae).
(pars iridis retinae).
They are the continuation of
They are the continuation of
pars ciliaris retinae.
pars ciliaris retinae.
====
RETINA
I
I
t
t
i
i
s
s
c
c
o
o
m
m
p
p
o
o
s
s
e
e
d
d
o
o
f
f
1
1
0
0
d
d
i
i
s
s
t
t
i
i
n
n
c
c
t
t
l
l
a
a
y
y
e
e
r
r
s
s
(
(
f
f
r
r
o
o
m
m
o
o
u
u
t
t
s
s
i
i
d
d
e
e
t
t
o
o
i
i
n
n
s
s
i
i
d
d
e
e
)
)
:
:
1- Pigmented epithelium.
1- Pigmented epithelium.
2- Rods and cones layer.
2- Rods and cones layer.
3- Outer limiting membrane.
3- Outer limiting membrane.
4- Outer nuclear layer.
4- Outer nuclear layer.
5- Outer plexiform layer.
5- Outer plexiform layer.
6- Inner nuclear layer.
6- Inner nuclear layer.
7- Inner plexiform layer.
7- Inner plexiform layer.
8- Ganglion cell layer.
8- Ganglion cell layer.
9- Optic nerve fiber layer.
9- Optic nerve fiber layer.
10- Inner limiting layer.
10- Inner limiting layer.
RETINA (Cont.)
RETINA (Cont.)
P
P
i
i
g
g
m
m
e
e
n
n
t
t
e
e
d
d
E
E
p
p
i
i
t
t
h
h
e
e
l
l
i
i
u
u
m
m
:
:
Cuboidal to columnar cells (single layer).
Cuboidal to columnar cells (single layer).
Apical microvilli.
Apical microvilli.
Abundance of melanin granules.
Abundance of melanin granules.
Functions:
Functions:
1- Absorb light.
1- Absorb light.
2- Phagocytosis of membranous discs from
2- Phagocytosis of membranous discs from
tips of rods.
tips of rods.
3- Esterification of Vitamin A (in SER).
3- Esterification of Vitamin A (in SER).
RODS AND CONES LAYER (Cont.)
Are photoreceptor cells.
Are photoreceptor cells.
Each has:
Each has:
1. Dendrite formed of:
1. Dendrite formed of:
-Outer segment (OS): contains membranous discs
-Outer segment (OS): contains membranous discs
containing rhodopsin (in rods) and iodopsin (in cones).
containing rhodopsin (in rods) and iodopsin (in cones).
- Connecting Stalk: with modified cilium.
- Connecting Stalk: with modified cilium.
-Inner segment (IS).
-Inner segment (IS).
2. Cell body.
2. Cell body.
3. Axon: synapses with dendrite of bipolar neuron of inner
3. Axon: synapses with dendrite of bipolar neuron of inner
nuclear layer.
nuclear layer.
F
F
u
u
n
n
c
c
t
t
i
i
o
o
n
n
s
s
:
:
Rods are receptors for dim light ( low intensity light).
Rods are receptors for dim light ( low intensity light).
Cones are receptors for bright light and color vision
Cones are receptors for bright light and color vision
(red, green & blue).
(red, green & blue).
RETINA (Cont.)
O
O
u
u
t
t
e
e
r
r
l
l
i
i
m
m
i
i
t
t
i
i
n
n
g
g
m
m
e
e
m
m
b
b
r
r
a
a
n
n
e
e
:
:
–
A region of zonulae adherents junctions between Muller cells and the
A region of zonulae adherents junctions between Muller cells and the
photoreceptors.
photoreceptors.
O
O
u
u
t
t
e
e
r
r
n
n
u
u
c
c
l
l
e
e
a
a
r
r
l
l
a
a
y
y
e
e
r
r
:
:
–
Contains nuclei of the rods & cones.
Contains nuclei of the rods & cones.
O
O
u
u
t
t
e
e
r
r
p
p
l
l
e
e
x
x
i
i
f
f
o
o
r
r
m
m
l
l
a
a
y
y
e
e
r
r
:
:
–
Contains axodendritic synapses between the
Contains axodendritic synapses between the
photoreceptor cells and dendrites of bipolar and
photoreceptor cells and dendrites of bipolar and
horizontal cells.
horizontal cells.
I
I
n
n
n
n
e
e
r
r
n
n
u
u
c
c
l
l
e
e
a
a
r
r
l
l
a
a
y
y
e
e
r
r
:
:
–
C
C
o
o
n
n
t
t
a
a
i
i
n
n
s
s
t
t
h
h
e
e
n
n
u
u
c
c
l
l
e
e
i
i
o
o
f
f
:
:
1- Bipolar neurons.
1- Bipolar neurons.
2- Horizontal neurons.
2- Horizontal neurons.
3- Amacrine neurons (unipolar neurons):
3- Amacrine neurons (unipolar neurons):
4- Neuroglial cells (Muller cells) that extend
4- Neuroglial cells (Muller cells) that extend
between the vitreous body and the inner segments of rods and cones.
between the vitreous body and the inner segments of rods and cones.
RETINA (Cont.)
I
I
n
n
n
n
e
e
r
r
p
p
l
l
e
e
x
x
i
i
f
f
o
o
r
r
m
m
l
l
a
a
y
y
e
e
r
r
:
:
Contains axodendritic synapses between axons of bipolar
Contains axodendritic synapses between axons of bipolar
neurons and dendrites of ganglion cells and amacrine cells.
neurons and dendrites of ganglion cells and amacrine cells.
G
G
a
a
n
n
g
g
l
l
i
i
o
o
n
n
c
c
e
e
l
l
l
l
l
l
a
a
y
y
e
e
r
r
:
:
Contains cell bodies of large multipolar neurons
Contains cell bodies of large multipolar neurons
of the ganglion cells.
of the ganglion cells.
O
O
p
p
t
t
i
i
c
c
n
n
e
e
r
r
v
v
e
e
f
f
i
i
b
b
e
e
r
r
l
l
a
a
y
y
e
e
r
r
:
:
Contains unmyelinated axons of the ganglion cells.
Contains unmyelinated axons of the ganglion cells.
N.B. These axons become myelinated as the nerve
N.B. These axons become myelinated as the nerve
p
p
i
i
e
e
r
r
c
c
e
e
s
s
t
t
h
h
e
e
s
s
c
c
l
l
e
e
r
r
a
a
.
.
T
T
h
h
e
e
i
i
n
n
n
n
e
e
r
r
l
l
i
i
m
m
i
i
t
t
i
i
n
n
g
g
m
m
e
e
m
m
b
b
r
r
a
a
n
n
e
e
:
:
It is formed by the basal laminae of the Muller cells.
It is formed by the basal laminae of the Muller cells.
RETINA (Cont.)
F
F
o
o
v
v
e
e
a
a
c
c
e
e
n
n
t
t
r
r
a
a
l
l
i
i
s
s
:
:
It lies in the center of macula
It lies in the center of macula
lutea.
lutea.
Cones are highly concentrated
Cones are highly concentrated
in the fovea.
in the fovea.
It is responsible for visual
It is responsible for visual
acuity.
acuity.
RETINA (Cont.)
T
T
y
y
p
p
e
e
s
s
o
o
f
f
c
c
e
e
l
l
l
l
s
s
i
i
n
n
t
t
h
h
e
e
r
r
e
e
t
t
i
i
n
n
a
a
:
:
1- Pigmented epithelium.
1- Pigmented epithelium.
2- Nerve cells:
2- Nerve cells:
-
-
Photoreceptor cells (rods & cones)
Photoreceptor cells (rods & cones)
- Bipolar neurons.
- Bipolar neurons.
- Ganglion cells.
- Ganglion cells.
- Association neurons:
- Association neurons:
i. Horizontal cells.
i. Horizontal cells.
ii. Amacrine cells.
ii. Amacrine cells.
3- Neuroglial cells:
3- Neuroglial cells:
- Muller’s cells.
- Muller’s cells.
- Astrocytes.
- Astrocytes.
CONJUNCTIVA
It is the transparent mucous
It is the transparent mucous
membrane lining the inner surfaces
membrane lining the inner surfaces
of the eyelids
of the eyelids
(palpebral conjunctiva)
(palpebral conjunctiva)
and reflecting onto the sclera of the
and reflecting onto the sclera of the
anterior surface of the eye
anterior surface of the eye
(bulbar
(bulbar
conjunctiva).
conjunctiva).
L
L
/
/
M
M
:
:
1
1
-
-
E
E
p
p
i
i
t
t
h
h
e
e
l
l
i
i
u
u
m
m
:
:
S
S
t
t
r
r
a
a
t
t
i
i
f
f
i
i
e
e
d
d
c
c
o
o
l
l
u
u
m
m
n
n
a
a
r
r
e
e
p
p
i
i
t
t
h
h
e
e
l
l
i
i
u
u
m
m
w
w
i
i
t
t
h
h
numerous goblet cells.
numerous goblet cells.
2
2
-
-
L
L
a
a
m
m
i
i
n
n
a
a
p
p
r
r
o
o
p
p
r
r
i
i
a
a
:
:
Loose C.T.
Loose C.T.
GOOD
GOOD
LUCK
LUCK
This detailed guide covers the histology of the eye, including the general structure and microscopic details of the cornea, retina, sclera, and more. Explore the layers and functions of the cornea, learn about the three tunics of the eye bulb, and discover the importance of structures like Descemet's membrane and the limbus.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
E N D
Presentation Transcript
Objectives By the end of this lecture, the student should be able to describe: The general structure of the eye. The microscopic structure of: Cornea. Retina.
EYE BULB Three coats (3 Tunics): 1- Fibrous tunic: Cornea. Sclera. 2- Vascular tunic: Choroid. Ciliary body. Iris. 3- Neural tunic: Retina.
CORNEA It is the transparent, avascular and highly innervated anterior portion of the fibrous coat. It is composed of 5 distinct layers: 1. Corneal epithelium. 2. Bowman s membrane. 3. Stroma. 4. Descemet s membrane. 5. Corneal endothelium.
CORNEA (Cont.) Corneal epithelium: Non-keratinized Stratified squamous epithelium. Contains numerous free nerve endings. Bowman s membrane: It is homogenous non-cellular layer containing type I collagen fibrils.
CORNEA (Cont.) Stroma: It is the thickest layer (about 90%). It is composed of parallel lamellae of dense collagenous C.T. Each lamella is composed mainly of parallel type I collagen fibers with long fibroblasts.
CORNEA (Cont.) Descemet s membrane: It is a thick basement membrane. Corneal endothelium: It is s simple squamous epithelium. Functions: 1- Formation of Descemet s membrane. 2- Keeping the stroma relatively dehydrated (sod. pump water withdrawal from the stroma).
LIMBUS (CORNEO SCLERAL JUNCTION) It is the transition region between the cornea and sclera. It is about 1.5 mm width. It is highly vascular. It contains: 1. Trabecular meshwork: Endothelium-lined spaces. It leads to canal of Schlemm. 2. Canal of Schlemm: It drains the aqueous humor into the venous system. Cornea Canal of Schlemm Iris Sclera Ciliary body Lens
SCLERA It covers the posterior 5/6 of the fibrous tunic. Sclera Proper: consists of interlacing bundles of type I collagen (dense collagenous C.T., irregular type). Melanocytes are located in the deeper regions.
CHOROID It is the vascular, pigmented posterior portion of the middle vascular tunic. Structure: It is composed mainly of loose C.T. with melanocytes. It is separated from the retina by its Bruch s membrane.
CILIARY BODY It is the anterior continuation of the choroid. It surrounds the lens. Structure: It is formed of loose vascular and pigmented C.T. that contains 3 bundles of smooth muscle cells (ciliary muscle). Its inner surface is lined by pars ciliaris retinae ( 2 rows of columnar cells; outer pigmented and inner non- pigmented layers) . Its inner surface is highly folded forming the ciliary processes.
CILIARY PROCESSES Processes project from the inner surface of the anterior 1/3 of the ciliary body towards the lens. Are covered by pars ciliaris retinae (2 rows of columnar cells). They give attachment to the lens suspensory ligaments (zonule fibers).
IRIS It is formed of 5 layers: 1- Anterior border layer: Incomplete layer of fibroblasts and melanocytes. 2- Stroma: Poorly vascularized C.T. with fibroblasts and melanocytes. 3- Vessel layer: Well-vascularized loose C.T. Centrally, it contains circularly arranged smooth muscle fibers (sphincter pupillae muscle). Stroma
IRIS 4- Dilator pupillae muscle layer: Contains radially arranged myoepithelial cells. 5- Posterior surface layer (pigmented epithelium layer): It is composed of 2 rows of pigmented epithelial cells (pars iridis retinae). They are the continuation of pars ciliaris retinae. ====
RETINA It is composed of 10 distinct layers(from outside to inside): 1- Pigmented epithelium. 2- Rods and cones layer. 3- Outer limiting membrane. 4- Outer nuclear layer. 5- Outer plexiform layer. 6- Inner nuclear layer. 7- Inner plexiform layer. 8- Ganglion cell layer. 9- Optic nerve fiber layer. 10- Inner limiting layer.
RETINA (Cont.) Pigmented Epithelium: Cuboidal to columnar cells (single layer). Apical microvilli. Abundance of melanin granules. Functions: 1- Absorb light. 2- Phagocytosis of membranous discs from tips of rods. 3- Esterification of Vitamin A (in SER).
RODS AND CONES LAYER (Cont.) Are photoreceptor cells. Each has: 1. Dendrite formed of: -Outer segment (OS): contains membranous discs containing rhodopsin (in rods) and iodopsin (in cones). - Connecting Stalk: with modified cilium. -Inner segment (IS). 2. Cell body. 3. Axon: synapses with dendrite of bipolar neuron of inner nuclear layer. Functions: Rods are receptors for dim light ( low intensity light). Cones are receptors for bright light and color vision (red, green & blue).
RETINA (Cont.) Outer limiting membrane: A region of zonulae adherents junctions between Muller cells and the photoreceptors. Outer nuclear layer: Contains nuclei of the rods & cones. Outer plexiform layer: Contains axodendritic synapses between the photoreceptor cells and dendrites of bipolar and horizontal cells. Inner nuclear layer: Contains the nuclei of: 1- Bipolar neurons. 2- Horizontal neurons. 3- Amacrine neurons (unipolar neurons): 4- Neuroglial cells (Muller cells) that extend between the vitreous body and the inner segments of rods and cones.
RETINA (Cont.) Inner plexiform layer: Contains axodendritic synapses between axons of bipolar neurons and dendrites of ganglion cells and amacrine cells. Ganglion cell layer: Contains cell bodies of large multipolar neurons of the ganglion cells. Optic nerve fiber layer: Contains unmyelinated axons of the ganglion cells. N.B. These axons become myelinated as the nerve pierces the sclera. The inner limiting membrane: It is formed by the basal laminae of the Muller cells.
RETINA (Cont.) Fovea centralis: It lies in the center of macula lutea. Cones are highly concentrated in the fovea. It is responsible for visual acuity.
RETINA (Cont.) Types of cells in the retina: 1- Pigmented epithelium. 2- Nerve cells: - Photoreceptor cells (rods & cones) - Bipolar neurons. - Ganglion cells. - Association neurons: i. Horizontal cells. ii. Amacrine cells. 3- Neuroglial cells: - Muller s cells. - Astrocytes.
CONJUNCTIVA It is the transparent mucous membrane lining the inner surfaces of the eyelids (palpebral conjunctiva) and reflecting onto the sclera of the anterior surface of the eye (bulbar conjunctiva). L/M: 1- Epithelium: Stratified columnar epithelium with numerous goblet cells. 2- Lamina propria: Loose C.T.
GOOD GOOD LUCK LUCK
