New Research Reveals Axons Have 'Pearls on a String' Structure

Advanced imaging shows axons are not cylindrical tubes but have a bead-like morphology, challenging century-old assumptions about neuron anatomy.

Scientists used high-pressure freezing electron microscopy to uncover a 'pearls on a string' structure in unmyelinated mouse axons, replacing the long-held belief that axons are smooth cylindrical tubes.
These bead-like formations, termed 'non-synaptic varicosities,' may influence the speed and efficiency of electrical signal transmission in the brain.
Changes in axonal membrane properties, such as reduced cholesterol levels, were found to decrease pearling and slow electrical signals.
The study suggests that axonal morphology is shaped by membrane mechanics and neuronal activity, with implications for understanding neurodegenerative diseases like Parkinson's.
Future research will investigate whether similar axonal structures exist in human brain tissue, including samples from patients with neurodegenerative conditions.