Ephrin-B Regulates the Ipsilateral Routing of Retinal Axons at the Optic Chiasm

Neuron. 2000 Mar;25(3):599-610. doi: 10.1016/s0896-6273(00)81063-6.

Abstract

In Xenopus tadpoles, all retinal ganglion cells (RGCs) send axons contralaterally across the optic chiasm. At metamorphosis, a subpopulation of EphB-expressing RGCs in the ventrotemporal retina begin to project ipsilaterally. However, when these metamorphic RGCs are grafted into embryos, they project contralaterally, suggesting that the embryonic chiasm lacks signals that guide axons ipsilaterally. Ephrin-B is expressed discretely at the chiasm of metamorphic but not premetamorphic Xenopus. When expressed prematurely in the embryonic chiasm, ephrin-B causes precocious ipsilateral projections from the EphB-expressing RGCs. Ephrin-B is also found in the chiasm of mammals, which have ipsilateral projections, but not in the chiasm of fish and birds, which do not. These results suggest that ephrin-B/EphB interactions play a key role in the sorting of axons at the vertebrate chiasm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / physiology*
  • Chick Embryo
  • Ephrin-B1
  • Eye / growth & development
  • Functional Laterality / drug effects
  • Functional Laterality / genetics
  • Gene Expression Regulation, Developmental / physiology
  • Larva / physiology
  • Membrane Proteins / analysis
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Optic Chiasm / chemistry
  • Optic Chiasm / cytology*
  • Optic Chiasm / growth & development*
  • Retinal Ganglion Cells / chemistry
  • Retinal Ganglion Cells / physiology*
  • Retinal Ganglion Cells / transplantation
  • Thyroxine / pharmacology
  • Transfection / methods
  • Vertebrates
  • Vision, Binocular / physiology
  • Visual Pathways / chemistry
  • Visual Pathways / cytology
  • Visual Pathways / growth & development
  • Xenopus / physiology*
  • Zebrafish

Substances

  • Ephrin-B1
  • Membrane Proteins
  • Thyroxine