A molecular pathway determining left-right asymmetry in chick embryogenesis

Cell. 1995 Sep 8;82(5):803-14. doi: 10.1016/0092-8674(95)90477-8.


While significant progress has been made in understanding the molecular events underlying the early specification of the antero-posterior and dorso-ventral axes, little information is available regarding the cellular or molecular basis for left-right (LR) differences in animal morphogenesis. We describe the expression patterns of three genes involved in LR determination in chick embryos: activin receptor IIa, Sonic hedgehog (Shh), and cNR-1 (related to the mouse gene nodal). These genes are expressed asymmetrically during and after gastrulation and regulate the expression of one another in a sequential pathway. Moreover, manipulation of the sidedness of either activin protein or Shh expression alters heart situs. Together, these observations identify a cascade of molecular asymmetry in that determines morphological LR asymmetry in the chick embryo.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Activins
  • Animals
  • Cell Differentiation / physiology
  • Cell Polarity / physiology*
  • Chick Embryo / physiology*
  • Embryonic Induction / physiology
  • Functional Laterality / genetics
  • Gastrula / physiology
  • Gene Expression / physiology
  • Heart / embryology
  • Hedgehog Proteins
  • In Situ Hybridization
  • Inhibins / physiology
  • Proteins / physiology
  • Trans-Activators*
  • Transforming Growth Factor beta / physiology


  • Hedgehog Proteins
  • Proteins
  • Trans-Activators
  • Transforming Growth Factor beta
  • Activins
  • Inhibins