Retinal axon growth at the optic chiasm: to cross or not to cross

Annu Rev Neurosci. 2008;31:295-315. doi: 10.1146/annurev.neuro.31.060407.125609.


At the optic chiasm, retinal ganglion cell axons from each eye converge and segregate into crossed and uncrossed projections, a pattern critical for binocular vision. Here, we review recent findings on optic chiasm development, highlighting the specific transcription factors and guidance cues that implement retinal axon divergence into crossed and uncrossed pathways. Although mechanisms underlying the formation of the uncrossed projection have been identified, the means by which retinal axons are guided across the midline are still unclear. In addition to directives provided by transcription factors and receptors in the retina, gene expression in the ventral diencephalon influences chiasm formation. Throughout this review, we compare guidance mechanisms at the optic chiasm with those in other midline models and highlight unanswered questions both for retinal axon growth and axon guidance in general.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Brain / embryology*
  • Brain / physiology
  • Functional Laterality / genetics
  • Gene Expression Regulation, Developmental / genetics
  • Growth Cones / physiology
  • Growth Cones / ultrastructure*
  • Humans
  • Intercellular Signaling Peptides and Proteins / genetics
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Optic Chiasm / embryology*
  • Optic Chiasm / physiology
  • Retina / embryology*
  • Retina / physiology
  • Retinal Ganglion Cells / cytology*
  • Retinal Ganglion Cells / physiology
  • Vision, Binocular / physiology*
  • Visual Pathways / embryology
  • Visual Pathways / physiology


  • Intercellular Signaling Peptides and Proteins