Lab 7: Retina, Macula and Fovea, Optic Disc and Optic Nerve
Layers of the Retina
(choroid) 1. RPE 2. Photoreceptor Layer 3. OLM 4. ONL 5. OPL 6. INL 7. IPL 8. Ganglion Cell Layer 9. Nerve Fiber Layer 10. ILM (vitreous)
MAcula
-contains many cones and few rods and the cones are slightly modified -good blood supply
Outer Segment
-contains visual pigments
Optic Nerve
-formed largely by ganglion cell axons from the retina -axons are unmyelinated within the eye then become myelinated at the lamina cribosa -a.k.a. CN II -dura mater, arachnoid mater, pia mater
Optic Disc
-ganglion cell axons leaving the eye interrupt the retina and choroid in this area -the lamina cribosa crosses across this
Cones
-less numerous -density outside of the macula decreases sharply -used in high illumination and photopic vision, providing color discrimination
Rods
-more numerous than cones -no rods in the fovea -used in low illumination and responsible for scotopic vision
Blind spot
-no light sensitivity
Outer Nuclear Layer
-nuclei and cell bodies of rods and cones
Photoreceptor Layer
-outer and inner segments of rods and cones
RPE
-outermost portion of the retina -contain large amounts of pigment that absorbs light entering the eye -not part of the neural retina
Ganglion Cells
-receive the impulse from the bipolar cells -fibers of these cells then carry the visual information in the nerve fiber layer toward the optic disc
Inner Segment
-responsible for general functioning. -highly active cells
Fovea
-retina is half as thick here -only layers present ( RPE, photoreceptors, and OLM and ILM -contains only cones -highest visual acuity
Outer Plexiform Layer
-synapses between photoreceptors -contains horizontal and bipolar cells
Bipolar Cells
-these receive impulse from the rods and cones and carry it toward the ganglion cells
Retina
Light- sensitive tissue of the eye; converts light entering the eye into a nerve impulse, which is carried along the visual pathway
Paracentral Retina
a concentric band surrounding the macula
Inner Nuclear Layer
cell bodies of bipolar, horizontal, and amacrine cells
Ganglion cell layer
cell bodies of ganglion cells
Muller's Cells
cells that nourish and support other retinal cells. -extend between the outer and inner limiting membranes and play a part in their formation
Cell body
contains the nucleus of the photoreceptor
Amacrine Cells
provide communication between ganglion cells
Horizontal Cells
provide communication between photoreceptors
Inner Plexiform Layer
synapses between bipolar, ganglion, and amacrine cells
Central Retina
the macula and fovea, at the posterior pole of the eye, and the areas of the retina giving the highest resolution of objects, i.e. the highest level of visual acuity
Peripheral Retina
the most anterior portion of the retina, extending to the ora serrata
Retinal Neurons
those carrying the impulse through the thickness of the retina i.e. running vertically through the retina
visual pigments
to absorb light entering the eye and convert it into a nervous impulse
Axon
transmit impulse to bipolar and horizontal cells via the synaptic body
Red-sensitive, Green sensitive, Blue-sensitive
visual pigment in human cones
Rhodopsin
visual pigment in human rods -is purple and bleach by light. -retinal and opsin
Photoreceptors (rods and cones)
where the visual process is initiated