Which neuroglial cell is the most common in the retina?

• A. Müller cells
• B. Astrocytes
• C. Microglia
• D. Oligodendrocytes

Answer: (A)

The main concept here is glial support in the retina, which is provided most abundantly by Müller cells. These radial glia span the entire thickness of the retina, from the inner limiting membrane to the outer limiting membrane, and they act as the principal scaffolding and support system for retinal neurons. Beyond structural support, Müller cells regulate the extracellular environment by buffering ions and pH, taking up and recycling neurotransmitters, and supplying metabolic support to photoreceptors and other neurons. They also contribute to the light-handling properties of the retina and participate in maintaining the blood-retinal barrier.

Other glial types are present but far less numerous in the retina. Astrocytes exist mainly in the nerve fiber layer and around blood vessels, microglia serve as resident immune cells, and oligodendrocytes are not typically found within the retina proper because retinal neurons’ axons are myelinated only after they exit the eye in the optic nerve. That’s why Müller cells are the most common retinal neuroglia.