Glial Cells Top: Glial cells, or glia, play an active role in brain functioning (Fields, 2013). This colored micrograph shows a star-shaped astrocyte (green) surrounding a neuron (red). Astrocytes provide connections between neurons and blood vessels in the brain and also help regulate communication among neurons.

Bottom: This colored micrograph shows the first stages of myelin formation by an oligodendrocyte (green). Like a spider spinning a web, the oligodendrocyte sends tendrils out to neighboring axons (red) and wraps layers of myelin around them in a spiral-shaped pattern.

Courtesy of Varsha Shukla, NICHD