Mis-expression of L1 on pre-crossing spinal commissural axons disrupts pathfinding at the ventral midline

Ralph Imondi, Angela R. Jevince, Amy W. Helms, Jane E. Johnson, Zaven Kaprielian

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


In vertebrates, spinal commissural axons project along a transverse path toward and across the floor plate (FP). Post-crossing commissural axons alter their responsiveness to FP-associated guidance cues and turn to project longitudinally in a fasciculated manner prior to extending away from the midline. The upregulation of the neural cell adhesion molecule L1 on crossed commissural axon segments has been proposed to facilitate pathfinding on the contralateral side of the FP. To explore this possibility in vivo, we used Math1 regulatory sequences to target L1 to commissural axons before they cross the ventral midline. L1 mis-expression did not alter the distribution of commissural axon-associated markers or the ventral extension of commissural axons toward the midline. However, commissural axons often stalled or inappropriately projected into the longitudinal plane at the ipsilateral FP margin. These observations suggest that L1-mediated pathfinding decisions are normally delayed until axons have crossed the ventral midline (VM).

Original languageEnglish (US)
Pages (from-to)462-471
Number of pages10
JournalMolecular and Cellular Neuroscience
Issue number4
StatePublished - Dec 2007


  • Altered responsiveness
  • Commissural axon
  • Fasciculation
  • Floor plate
  • L1
  • Math1

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience
  • Cell Biology


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