0805 - Eye Histology

Question 1

How is the retina organised?

Answer 1

Macula surrounds the central retina (fovea). Fovea is dominated by cones (colour perception) (except blue-sensitive, which are in some of the rest of the retina). Peripheral retina is dominated by rods (light perception).
7m cones, 100m rods

Question 2

Outline Muller cells

Answer 2

Act as neuroglia of the retina. Span the 10 layers of the retina to provide structural and metabolic support to neurons.

Question 3

What are the 10 layers of the retina?

Answer 3

1. Pigmented Epithelial cells -
2. Photoreceptor layer - Rod and cone cell processes.
3. Outer limiting membrane - Divide processes from body.
4. Outer Nuclear Layer - Photoreceptor cell bodies.
5. Outer Plexiform Layer - Synapse photoreceptors and integrating neurons.
6. Inner Nuclear/Bipolar Cell Layer - Integrating neuron cell bodies
7. Inner plexiform layer - Synapse integrating and optic tract neurons
8. Ganglion cell layer - Cell bodies of optic tract neurons
9. Afferent Nerve fibres - Axons of optic tract neurons
10. Inner limiting membrane - Separate retina from vitreous body.

Question 4

What is the function of pigmented epithelial cells?

Answer 4

Retinal pigment epithelium.
Absorb stray light - increasing acuity and reducing reactive oxygen species
Phagocytosis of rod photoreceptor disks which are shed continually.
architectural and metabolic support to photoreceptors.
Also play role in immune privilege.

Question 5

What are the cell types of the retina?

Answer 5

Ganglion cells - of afferent fibres.
Bipolar, Horizontal, and Amacrine cells (integrating neurons)
Photoreceptors - Rods and cones
Pigmented epithelial cells
Neuron support cells - muller cells.

Question 6

What are 5 differences between rods and cones?

Answer 6

Shape - outer segment as rod or cone.
Cones have more membranous disks
Cone disk membrane is continuous with the plasma membrane.
Disks are not shed
Can see colour as opposed to light.

Question 7

How do rod photoreceptors allow you to see?

Answer 7

Light hits rhodopsin, triggering a conformational change and leading to an action potential.