special senses (2)
TRANSCRIPT
Special sensory organs
Olfactory mucosa
Gustatory cells
Retina
Internal ear
– cochlea
– Semicircular canal
Eye lid Skin – Stratified squamous
keratinized
– dermis
Connective tissue layer
Skeletal muscle (orbicularis oculi)
Tarsal plate with glands
Conjunctiva – Stratified squamous non
keratinized
Cornea
Five layered structure
– Outer corneal epithelium
– Bowman’s membrane
– Substantia propria
– Descemet’s membrane
– Inner endothelium
Corneal epithelium – Thin Stratified squamous non
keratinized-5 LAYER
– Papilla absent
– Straight plane avoids refraction
Bowman’s membrane – Anterior limiting membrane
– Homogenous amorphous with fine collagen
– Forms basement membrane for corneal epithelium
Substantia propria
– Stroma of cornea
– Transparent
– Parallel arranged collagen fibers
– Ground matrix
– glycoaminoglycans+fibroblast
– Collagen are arranged in alternate lamellae with regular spacing for light transmission
Descemet’s membrane
– Posterior limiting
membrane
– Thin and homogenous
– Layers continues into irido
corneal angle
Endothelium
– Single polygonal cells on
a basement membrane
RETINA Nervous coat
Extends from optic disc
to ora serrata
Posterior part of retina
shows yellow spot
macula lutea
Optic disc – area where
optic nerve emerges
Layers of retina 1. PIGMENT LAYER
2. LAMINA OF RODS AND CONES
3. EXTERNAL LIMITING MEMBRANE
4. OUTER NUCLEAR LAYER
5. OUTER PLEXIFORM LAYER
6. INNER NUCLEAR LAYER
7. INNER PLEXIFORM LAYER
8. GANGLION CELL LAYER
9. LAMINA OF NERVE FIBERS
10. INTERNAL LIMITING MEMBRANE
PIGMENT EPITHELIUM
Low cubical cells Basement membrane known as Bruch’s membrane Cells faces towards rods and cones Appear black due to melanin pigments One cell contacts > 12 rods and cones functions – Phagocyte, – antireflection of light, – blood retinal barrier
Rods and Cones
Photoreceptors
Cones are wider and tapers at the end
Rods are narrow and cylindrical
Under EM they exhibit outer and inner segments
Inner segments contains mitochondria for energy
Outer segment shows discoidal membrane
External limiting membrane
– Sieve like membrane
– Supports rods and cones
– Appears pink linear marking
– Represents zona adherens
of Muller cells
Outer nuclear layer
– Nucleus of rods and cones
– Several layers
ONL
OLM
Outer plexiform layer
– Synaptic area between rods and cones with
– Bipolar neurons
– Horizontal cells
– Amacrine cells
Inner nuclear layer
– Shows nucleus of bipolar, horizontal cells, amacrine cells, Muller cells
Inner plexiform layer
– Synaptic process of
bipolar, amacrine, Muller
with ganglion cells
– Plexiform appearance
Ganglion layer
– Cell body and nucleus of
large ganglion cells and
amacrine cells
Nerve fibers
– axons of ganglion
cells
Internal limiting
membrane
– Homogenous layer
– Formed by end feet of
Muller cell and
astrocytes
OPTIC NERVE
MENINGES
– DURA
– ARACHNOID
– PIA
NERVE FIBERS
– MYELINATED
– ARRANGED IN FASCICULI
– CENTRAL ARTERY OF RETINA