Retina and RPE part 3 Flashcards
What are 3 key types of retinal neuroglia?
- Astrocytes
- Müller cells
- Microglia
What is the principal and predominant glial cell in the retina?
Müller cells
Which central nervous system cells are Müller cells analogous to?
oligodendrocytes
Within which 3 retinal layers are astrocytes predominantly found in, and what is their outer limit?
3 layers:
- Nerve fibre layer
- Ganglion cell layer
- Inner plexiform layer (site of cell bodies)
Outer limit: vitread aspect of the inner nuclear layer in humans
What is the structural arrangement of astrocytes?
they form an irregualr honeycomb scaffold beween vessels and neurones perpendicular to the Müller cells
What are the 2 shapes that astrocytes may appear as?
- fibrous (elongated)
- protoplasmic (rounded)
What structures are contained within astrocytes and what are these structures made of?
abundant cytoplasmic structural fibrils (10nm in diameter) consisting of glial fibrillary acid protein (GFAP)
In which parts of the astrocyte cells is there a high concentration of expression of GFAP (glial fibrillary acid protein)?
where the cells are stressed
How are astrocytes often oriented?
perpendicular to the direction of the neurone cell bodies or processes, such as in the nerve fibre layer
What may be the role of atrocytes?
isolate the receptive surfaes of neurones int eh retina thus preventing unwanted signals or effects in neighbouring neurones
What substance is abundant in the cytoplasms of astrocytes?
glycogen
What connections due astrocytes form with neighbouring astrocytes?
gap junctions
What is shown in the image?

scanning electron micrograph of astrocytes surrounding nerve fibre bundles in the inner retina
What is shown in the image?
relations of astrocytes shown with antibody to glial acidic fibrillary protein (GFAP) red and lectin-stained vessels (pale gree)

How are astrocytes related to damage in the retina?
when injured, the retina frequently responds by forming astroglial scars
normal age-related degenerative processes in the peripheral retina (microcystoid degeneration) are accompanied by astrocyte proliferation
What can disruption of the inner limiting membrane of the retina result in (in relation to astrocytes)?
astrocyte prolifeation in the subhyaloid spaec and in the vitreous itself
What are Müller cells?
the principal supporting glial cells of the retina
Which cells are Müller cells considered analogous with in the CNS?
radial glial or ependymal cells
What is the orientation of Müller cells in the retina?
radial orientation
What do Müller cells extend between?
- extend through the depths of the retina from the inner surface, where their expanded ‘foot process’ lies adjacent to the inner limiting membrane (ILM)
- to their outer limit, where they have adherens junctions with photoreceptor inner segments to form the external limiting membrane (ELM)
What is the role of Müller cells in the retina and how does this relate to their arrangement?
provide a trellis-basket-like support for the retina, also may help to nourish and maintain the outer retina which lacks a direct blood supply
photoreceptors extend the business end of segments through the gaps in the ELM

What is the arrangement of Müller cells in the retina in relation to other retinal structures?
they envelop blood vessels, neuronal cell bodies and processes, creating glial ‘tunnels’ via a series of cytoplasmic processes

How much glycogen is there in Müller cells?
they contain little glycogen
What 2 organelles are in abundance in the Müller cell cytoplasm and what does this say about their function?
- endoplasmic reticulum
- microtubules
role:
- protein synthesis
- intracellular transport
- secretion




