A new study challenges the long-held belief that axons, brain cell extensions, are tube-like. Axons in brain cells resemble a string of pearls rather than smooth tubes, according to Johns Hopkins researchers. This discovery, aided by advanced imaging and modeling, reveals how physical and membrane properties influence axon structure and function, challenging long-held beliefs and offering insights into brain signaling and disease.
Using advanced freezing electron microscopy, researchers found these bead-like formations, termed “non-synaptic varicosities,” across mouse neurons. These structures may influence brain signaling by modulating ion flow and electrical signal speed. Changes in membrane stiffness, such as reduced cholesterol levels, alter the pearls’ size and signal transmission ability.
This discovery reshapes our understanding of neuron structure and opens doors for exploring its implications in neurodegenerative diseases. Future work will examine these formations in human brain tissues.
Key Facts:
To be able to see axons on brain cells (neurons), which are 100 times smaller than the width of a human hair, the scientists used high pressure freezing electron microscopy. Like standard electron microscopy, which shoots beams of electrons at a cell to outline its structure, Watanabe and his team froze mouse neurons to preserve the structures’ shape.
Using advanced freezing electron microscopy, researchers found these bead-like formations, termed “non-synaptic varicosities,” across mouse neurons. These structures may influence brain signaling by modulating ion flow and electrical signal speed. Changes in membrane stiffness, such as reduced cholesterol levels, alter the pearls’ size and signal transmission ability.
This discovery reshapes our understanding of neuron structure and opens doors for exploring its implications in neurodegenerative diseases. Future work will examine these formations in human brain tissues.
Key Facts:
- Axons exhibit “pearl-on-a-string” shapes, not constant cylindrical tubes.
- Removing cholesterol in axons reduces pearling and slows electrical signals.
- High-frequency electrical stimulation temporarily swells these pearl structures.
To be able to see axons on brain cells (neurons), which are 100 times smaller than the width of a human hair, the scientists used high pressure freezing electron microscopy. Like standard electron microscopy, which shoots beams of electrons at a cell to outline its structure, Watanabe and his team froze mouse neurons to preserve the structures’ shape.
