What Are Glial Cells and What Do They Do?

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Oligodendrocytes come from neural stem cells. The word is composed of Greek terms that, all together, mean “cells with several branches.” Their main purpose is to help information move faster along axons.

Oligodendrocytes look like spikey balls. On the tips of their spikes are white, shiny membranes that wrap around the axons on nerve cells. Their purpose is to form a protective layer, like the plastic insulation on electrical wires. This protective layer is called the myelin sheath.

The sheath isn’t continuous, though. There’s a gap between each membrane that’s called the “node of Ranvier,” and it’s the node that helps electrical signals spread efficiently along nerve cells. The signal actually hops from one node to the next, which increases the velocity of the nerve conduction while also reducing how much energy it takes to transmit it. Signals along myelinated nerves can travel as fast as 200 miles per second.

At birth, you only have a few myelinated axons, and the amount of them keeps growing until you’re about 25- to 30-years-old.

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