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Keywords:

  • Hensen's node;
  • node;
  • asymmetry;
  • time-lapse imaging;
  • cellular motion;
  • tissue motion;
  • Fgf8;
  • Shh

Abstract

Current hypotheses regarding vertebrate left-right asymmetry patterns are based on the presumption that genetic regulatory networks specify sidedness via extracellular morphogens and/or ciliary activity. We show empirical time-lapse evidence for an asymmetric rotation of epiblastic nodal tissue in avian embryos. This rotation spans the interval when initial symmetric expression of Shh and Fgf8 becomes asymmetrical with respect to the midline. Anat Rec, 292:557–561, 2009. © 2009 Wiley-Liss, Inc.