Insulating sheath on nerve cells isn’t an even coat

A nerve cell’s long, slender tentacle isn’t evenly coated with an insulating sheath as scientists had thought.

Instead, many nerve cells in the brains of mice have stretches of these tentacles, called axons, that are naked, researchers report April 18 in Science. The unsheathed feeler can be as long as 80 micrometers. Nerve cells can also have specific patterns in the gaps of the insulating layer, called myelin. The differences in the thickness of that coating may control how fast signals travel between nerve cells, the scientists suggest.

The finding could have implications for understanding nerve-based diseases, such as multiple sclerosis, and improve scientists’ understanding of how signals are transmitted in the brain.