Glia Cell Types
There are several glial cell types: astrocytes, microglia, Müller, Schwann, and oligodendrocytes, among others. Each have their own tasks and function differently than neurons.
Glia have historically been categorized by their association with neurons. It has not been a rational taxonomy.
German anatomist Henrich Müller described retinal glia cells in 1851. Müller cells funnel light to green and red color (cone) receptors, increasing light absorption 10 times. Blue light is shuttled to rod cells, enabling night vision. Müller cells communicate with one another within the retina and modulate signaling out of the retina to the brain.
German physiologist Theodore Schwann, one of Müller’s pupils, discovered glia cells in the peripheral nervous system. Schwann cells reside in the myelin sheath coating the axon of neurons. Schwann cells speed nerve signals and help control muscle contractions though a feedback mechanism.