PUBLICATION

Pioneer axons employ Cajal's battering ram to enter the spinal cord

Authors
Nichols, E.L., Smith, C.J.
ID
ZDB-PUB-190206-6
Date
2019
Source
Nature communications   10: 562 (Journal)
Registered Authors
Smith, Cody
Keywords
none
MeSH Terms
  • Animals
  • Axons
  • Ganglia, Spinal/anatomy & histology
  • Ganglia, Spinal/cytology
  • Models, Biological
  • Neural Crest/cytology
  • Spinal Cord/anatomy & histology*
  • Spinal Nerve Roots/anatomy & histology*
  • Spinal Nerve Roots/cytology
  • Zebrafish/anatomy & histology*
PubMed
30718484 Full text @ Nat. Commun.
Abstract
Sensory axons must traverse a spinal cord glia limitans to connect the brain with the periphery. The fundamental mechanism of how these axons enter the spinal cord is still debatable; both Ramon y Cajal's battering ram hypothesis and a boundary cap model have been proposed. To distinguish between these hypotheses, we visualized the entry of pioneer axons into the dorsal root entry zone (DREZ) with time-lapse imaging in zebrafish. Here, we identify that DRG pioneer axons enter the DREZ before the arrival of neural crest cells at the DREZ. Instead, actin-rich invadopodia in the pioneer axon are necessary and sufficient for DREZ entry. Using photoactivable Rac1, we demonstrate cell-autonomous functioning of invasive structures in pioneer axon spinal entry. Together these data support the model that actin-rich invasion structures dynamically drive pioneer axon entry into the spinal cord, indicating that distinct pioneer and secondary events occur at the DREZ.
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