histology of eye
DESCRIPTION
HISTOLOGY OF EYE. Dr Iram Tassaduq. EPITHELIUM. Stratified squamous non keratinized Consist of 5-6 layer Active mitosis Turnover time for cells is 6-7 days Extremely sensitive to touch. BOWMANS MEMBRANE. Consists of collagen fibers Acellular clear membrane lie under the epithelium - PowerPoint PPT PresentationTRANSCRIPT
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HISTOLOGY OF EYE
Dr Iram Tassaduq
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EPITHELIUM Stratified
squamous non keratinized
Consist of 5-6 layer
Active mitosis Turnover time
for cells is 6-7 days
Extremely sensitive to touch
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BOWMANS MEMBRANE Consists of collagen
fibers Acellular clear
membrane lie under the epithelium
Cannot be regenerated if destroyed
Provides strength to cornea
Acts as a barrier against spread of infections
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CORNEAL STROMA Many layers of
collagen bundles run parallel to each other and parallel to the surface of the cornea making the cornea transparent,
Avascular structure Nuclei of fibroblasts 90% of corneal
thickness
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DESCEMENTS MEMBRANE Fine
collagenous filaments
5-10 micrometer thick
Regenerates quickly
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ENDOTHELIUM
Single layer of flat hexagonal cells with no mitosis
Pumps water out Prevent corneal
edema opacification
Maintain corneal transparency
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LENS Capsule Refractile and formed of
type IV collagen Sub capsular
epithelium Single layer of cuboidal
epithelium present on anterior surface
Lens fibers Highly differentiated
cells.
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LENS FIBERS Form the body of the lens.
located deep to the subcapsular epithelium.
Nucleated in the soft, outer cortex of the lens. As new lens fibers are added to the periphery of the cortex, lens fibers located deeper in the cortex loose their nuclei .
Cytoplasm filled with crystalline proteins. These proteins are responsible for the transparency .
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RETINA Innermost layer of eye ball Develops from double walled optic cup Outer layer forms pigment epithelium Inner layer forms neural retina
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RETINA The retina is the site of sensory
transduction The retina is nervous tissue composed of
6 major types of neurons and one special type of glial-like cell (the Muller cell)
The organization of the retina is based on a three neuron chain (photoreceptor cell to bipolar cell to ganglion cell)
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MAJOR RETINAL CELLSRODS Thin elongated cells Composed of inner and outer segments 120 million photoreceptor cells called
rods (responsible for peripheral and dim light vision)
Contain rhodopsin
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MAJOR RETINAL CELLSCONES Lesser in number than rods Responsible for providing central, bright
light, fine detail, and color vision Contain visual pigment iodopsin
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MAJOR RETINAL CELLS Horizontal cells -
interconnect groups of photoreceptor cells
Bipolar cells - interconnect photoreceptor cells with ganglion cells
Amacrine cells interconnect groups of ganglion cells and bipolar cells
Ganglion cells possess long axons that extend through the nerve fiber layer of the retina and then come together to form the optic nerve 17
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LAYERS OF RETINA Pigment epithelium The layer of rods and cones External limiting membrane. The outer nuclear layer Outer plexiform layer Inner nuclear layer. The internal plexiform layer Ganglion cell layer. Layer of optic nerve fibers The internal limiting membrane
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PIGMENT EPITHELIUM Consist of columnar
cells Absorbs light Synthesizes
melanin granules Vitamin A
metabolism Cells have
phagocytic properties
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LAYER OF RODS AND CONES
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EXTERNAL LIMITING MEMBRANE Not a true
membrane Formed of row of
zonula adherens between muller cells and rods and cones
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OUTER NUCLEAR LAYER
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OUTER PLEXIFORM LAYER Formed by the
processes of photoreceptor cells and retinal neuronal cells that is horizontal, bipolar and amacrine cells
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INNER NUCLEAR LAYER Consist of
nuclei of bipolar, amacrine,
horizontal and muller cells
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INTERNAL PLEXIFORM LAYER
Formed of complex intermingled nerve cell processes
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GANGLION CELL LAYER Consist of cell
bodies of large multipolar neurons
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OPTIC NERVE LAYER Consist of axons of
ganglion cells
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INTERNAL L+-IMITING MEMBRANE
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