To pull off all the processing that goes on between your ears, the brain needs information from all over your body. Some of the longest neurons, for example, stretch the length of your leg from your big toe to the bottom of your spine. Much as rubber covers long-distance electrical wires for insulation, nerve fibers known as axons (seen here in brown) are wrapped in a fatty material called myelin (green) that lets them carry signals quickly from head to toe.
But those protective sheaths aren’t part of the neuron itself. Outside of the brain and spinal cord, they come from Schwann cells (purple). The type shown here supports just one section of a single axon, wrapping around it again and again like a bandage.
Charlie Wood is a science writer with a bachelor’s degree in physics from Brown University and a master’s degree in science journalism from New York University. In previous lives he taught physics in Mozambique and English in Japan, but these days he freelances from his home in New York.
Bhatheja K, Field J. Schwann cells: Origins and role in axonal maintenance and regeneration. The International Journal of Biochemistry & Cell Biology 38(12): 1995-1999 (2006).
Kamada T, Koda M, Dezawa M, Yoshinaga K, Hashimoto M, et al. Transplantation of bone marrow stromal cell-derived Schwann cells promotes axonal regeneration and functional recovery after complete transection of adult rat spinal cord. J Neuropathol Exp Neurol. 64(1):37-45 (2005).
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