POSTERIOR SEGMENT - Retinal Pigment Epithelium

Question 1

What are the functions of the RPE?

Answer 1

1. Pigmented (melanosomes with melanin) responsible for absorption of bright light
2. Waste products from rod and cone cells (outer segment) are phagocytosed by RPE cells

Question 2

What is the structure of rods and cones from the RPE to vitreous?

Answer 2

Outer segment (transductive) –>
inner segment (region for maintenance of cellular homeostasis) –>
nuclear region (outer nuclear layers) –> transmissive region (outer plexiform/ synaptic layer)

Question 3

Does the retina have a high or low flow rate? Does the retina have high or low oxygen exchange?

Does the choroid have a high or low flow rate? Does the retina have a high or low oxygen exchange?

Answer 3

retina: low flow rate, high oxygen exchange
choroidal: high flow rate, low oxygen exchange

Question 4

When does rod phagocytosis occur?
When does cone phagocytosis occur?

Answer 4

Rod: onset of light exposure
Cone: random, onset of darkness

Question 5

How big are the RPE cells ?

Answer 5

14um tall.

Question 6

How are RPE cells connected with each other and what do they contain?

Answer 6

Connection: tight junction
Contain: Lysosomes and mitochondria.

Question 7

RPE cells are more flattened in the centre than in the periphery. True or false?

RPE cells are hexagonal and highly organised. True or false?

Answer 7

False: More flatter in the periphery than in the centre.

True: hexagonal and highly organised.

Question 8

What are the layers of Bruch’s membrane? (5)

Answer 8

1. RPE basal lamina
2. Inner collagenous zone
3. Middle elastic layer
4. Outer collagenous zone
5. Basement membrane of endothelial cells in choriocapillaris

Question 9

What is the epithelium of the RPE?

Answer 9

Monolayer of columnar epithelial cells.