Source of Early Regenerating Axons in Lamprey Spinal Cord Revealed by Wholemount Optical Clearing with BABB

This paper investigates the origins of axons that regenerate early after spinal cord injury in lampreys. Researchers used a tissue clearing technique called BABB to enhance the resolution of neuronal structures in wholemounts of the lamprey central nervous system. By combining BABB clearing with fluorescent labeling, they identified that many of the early regenerating axons originate from small neurons in the brainstem. They also found that some propriospinal neurons located near the injury site contribute to early regeneration. The early regenerating axons were of small caliber and showed little retraction after injury. This study provides insights into the mechanisms of axon regeneration and functional recovery after spinal cord injury.

• 1
  Over 50% of the early regenerating axons belonged to small neurons in the brainstem, specifically in the posterior and middle rhombencephalic reticular nuclei (PRRN and MRRN).
• 2
  Some propriospinal neurons located close to the TX also contributed to early regeneration, but their numbers decreased with distance from the original lesion.
• 3
  Compared with axotomized giant axons, the early regenerating axons were of small caliber and showed little retraction, probably because they resealed rapidly after injury.