The Retina Flashcards
What are the 10 layers of the retina?
1) Retinal Pigment epithelium - simple cuboidal
2) Rod and cone photoreceptor layer
3) External limiting membrane
4) Outer nuclear layer
5) Outer plexiform layer - synaptic layer
6) Inner nuclear layer - cell bodies of
7) Inner plexiform layer
8) Ganglion cell layer
9) Nerve fibre layer
10) Inner limiting membrane
Which direction does light travel?
From inner limiting membrane to retinal pigment epithelium
What is the thickness of the entire retina?
220 microns
The nuclei of which cells form a single layer
often penetrating the external limiting
membrane and what is the size of these nuclei?
The cone cell nuclei and 7.5 microns
Note the discontinuities of the external
limiting membrane. What is the cause of
this?
Discontinuities are due to tight junctions
What is the function of the external limiting
membrane?
- Maintains the structure of the retina
- The ELM acts as a permeability barrier, keeps osmotic pressure and prevents fluid from flowing out
Note how the tips of the outer segments have
been cut obliquely
Tips are curled due to dehydration when preparing the slide
How are the photoreceptor outer segments
attached to the RPE?
Via interstitial retinal binding proteins
Where would you see blood vessels within the retina?
The inner 5 layers
How do those layers of the retina without a direct blood supply receive nutrients?
Receive nutrients from the choriocapillaris
Differentiate the inner segments and nuclei of
rods and cones
-cone inner segments are fatter, cone nuclei are single layer of pale oval whereas rod nuclei are several rows of darker nuclei
Where is the macula region located?
The macula region of the retina is centered 4mm temporal and 0.8mm inferior to the optic disc
What are the 4 concentric layers of the macula?
Central foveola, which surrounded by the fovea, parafovea and perifovea
How these foveolar cones differ from those elsewhere in the retina? (refer to tangental
sections of parafovea above for comparison).
Fovea has dense and smaller cones
The spacing and size of these foveolar cones relative to the outer retina?
Outer = smaller/thinner cones so more white which is the interphotoreceptor matrix Inner = thicker and bigger cones
