Nerve cells. Light micrograph of a section through the white matter of the brain. The black bodies with processes are astrocytes, which are a type of glial cell. They provide support and protection for neurons (nerves) by surrounding neurons and holding them in place. They also supply them with nutrients and oxygen, and destroy and remove damaged neurons. Astrocytes do not conduct electrical signals and therefore can insulate one neuron from another. The thick dark lines are capillaries. Mag: x190 when 10cm wide.