Tuesday 24 July 2007
The leftward movement of fluid at the ventral node, called nodal flow, is the central process in symmetry breaking on the left-right axis. Nodal flow is autonomously generated by the rotation of cilia that are tilted toward the posterior on cells of the ventral node. These cilia are built by transport via the KIF3 motor complex.
How nodal flow is interpreted to create left-right asymmetry has been a matter of debate.
Nodal vesicular parcels (NVPs)
The leftward movement of membrane-sheathed particles, called nodal vesicular parcels (NVPs), may result in the activation of the non-canonical Hedgehog signaling pathway, an asymmetric elevation in intracellular Ca(2+) and changes in gene expression.
Schier, A. F.; Shen, M. M. : Nodal signalling in vertebrate development. Nature 403: 385-389, 2000. PubMed ID : 10667782