Microscopic structure of retina dr paresh varsat

presentation of microscopic structure of retina

1. MICROSCOPIC
MICROSCOPIC
STRUCTURE OF
STRUCTURE OF
RETINA
RETINA
DR.PARESH VARSAT
RETINA UNIT

2. MICROSCOPIC
STRUCTURES OF RETINA:

3. Retina consists of 10 layers
from outward to inwards:
01.Retinal pig epithelium
02.Layer of rods & cones
03.Ext limiting memb
04.Outer nuclear layer
05.Outer plexiform layer
06.Inner nucler layer
07.Inner plexiform layer
08.Ganglion cell layer
09.Nerve fibre layer
010.Internal limiting
membrane

5. Retinal Pigment Epithelium:
0Outermost layer of retina
0It consists of a single layer of hexagonal shaped
cells containing pig.
0Responsible for granular appearance of fundus
0RPE is firmly adherant to bruch’s memb.&loosely
attached to layer of rods & cones
0The potential space b/w RPE & sensory retina is
called subretinal space
0 In retinal detachment fluid collection in this
space is called subretinal fluid

6. Functions Of RPE
0Photoreceptor renewal & recycling of vitamin A
0Maintains inegrity of subretinal space by forming
outer blood retinal barrier & actively pumping
ions & water out of it
0Transport of nutrients & metabolites through the
blood retinal barrier
0RPE cells have phagocytic action
0Mechanical support to the processes of
photoreceptors.
0Manufactures pig.which has optical function in
absorbing light

7. Layer Of Rods & Cones :
(photoreceptor cell layer)
0Rods & Cones are the end organs of vision which transform
light energy into visual impulse
0Rods contain a photosensitive subs. Visual purple
(rhodopsin)& subserve the peripheral vision & vision of low
illumination(scotopic vision)
0Cones contain a photosensitive substance(iodopsin) &
responsible for highly descriminatory central vision
(photopic vision) & colour.
0There are abt. 120 million rods & 6.5 million cones
0The highest density of cones is at fovea & their no. reduces
outside fovea
0Rods are absent at the fovea in an area of 0.35mm &
maximum below the optic disc, their no. reduces towards
the periphery

9. Structure Of Photorecptor
1)Cell body
2)Nucleus (outer nuclear layer)
3)Cell processes (outer plexiform layer)
4)Outer and inner segments (upto external limiting
membrane)

10. External Limiting Membrane:
0 fenestrated membrane extends from the ora serrata
to the edge of the optic disc through which pass
processes of the rods & cones
0Formed by the junctions b/w the cell membrane of
photorecptors & muller’s cell

11. Outer Nuclear Layer:
0Formed by the nuclei of rods & cones
0Cone nuclei are larger than rod nuclei & lie in a single
layer next to the internal limiting membrane
0Rod nuclei form the bulk of this multilayered layer
except in the cone dominated foveal region

12. Region of retina Layer of nuclei Thickness(micrometer)
Nasal to Disc 8 to 9 45
Temporal to Disc 4 22
Foveal region 10 50
Rest of the retina
except ora serrata
1 layer of cone
4 layer of rod
27

13. Outer Plexiform Layer:
(junction b/w end organ of vision & 1
st
order neuron)
0Contains the synapses b/w the rod spherules & cone
pedicles with the dendrites of the bipolar cells &
processes of the horizontal cells
0Also known as Henle’s layer (oblique fiber arranged
deviated from the fovea)

14. Inner nuclear Layer:
0Consist of the following-
0Bipolar cell
0Horizontal cells
0Amacrine cells
0Muller’s cells
0Capillaries of the central retinal vessels

15. 1)Bipolar cells
0Neurons of first order of vision
0The body of the bipolar cells consists entirely of the
nucleus which lies in the inner nuclear layer
0There are nine types of bipolar cell-

17. 2)Horizontal neurons
0These are flat cells having numerous horizontal
associative & neuronal interconntections b/w
photoreceptors & bipolar cells in the outer plexiform
layer
0Two type of cell-
0Type a-seven group of dendrites have contact with
triad of seven cone pedicles and single axons has
contact with distant cone triad
0Type b-dendrites have contact with rod receptor only
and axons with distant rod cell

18. 3)Amacrine cells
0Situated within the innermost part of this layer
0Single process have connection with axons of bipolar cell
and dendrites & soma of ganglion
0Perform an integrative function similar to horizontal cells
4)Muller’s cell
0The nucleus & cell bodies of the cells are located within the
inner nucler layer
0Provide structural support & contribute to the metabolisn
of the sensory retina
5)Glial cells
0 astrocytes,microglia & oligodendrocytes

19. Inner plexiform layer:
0Consists of synapses b/w the axons of bipolar cells,
dendrites of ganglion cells & the processes of
integrative amacrine cells
0Absent at the foveola

20. Ganglion cell layer:
(second order neuron of visual pathway)
0The cell bodies & the nuclei of the ganglion cells lie in this layer
0It is composed of a single row of cells except in the macular
region where it is multilayered
0Absent in the foveola
Classification-
1.W,X & Y ganglion cell
2.P & M ganglion cell
3.Monosynaptic(central retina) & poly synaptic
ganglion(peripheral retina)

21. Nerve fibre layer:
0Consist of the unmyelinated axon of the ganglion
cells(centripetal nereve fiber) which converge at the
optic nerve head,pass though lamina cribrosa
0This layer also contains -
Centrifugal nerve fibres
Processes of muller’s cells
Neuroglial cells
0
Rich bed of superficial capillary network is present
in this layer

22. Arrangements of nerve fibers in
Retina & Optic disc & Thickness

23. Internal limiting membrane
0Consists of a PAS positive true basement membrane
that forms interface b/w retina & vitreous
0 consist of 4 elements -
1) collagen fibrils
2) proteoglycans of vitreous
3) basement membrane
4) plasma membrane of muller cells

24. 0In this area, there are no rods.
0Cones are tightly packed and other layers of retina are
very thin.
0Its central part (foveola) largely consists of cones and
their nuclei covered by a thin internal limiting
membrane.
0All other retinal layers are absent in this region.
0In the foveal region surrounding the foveola, the cone
axons are arranged obliquely (Henle’s layer or outer
plexiform layer) to reach the margin of the fovea
Structure of fovea centralis:

25. Fovea centralis:

26. THANKS FOR PATIENCE…!