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. Author manuscript; available in PMC: 2008 Apr 30.
Published in final edited form as: Prog Biophys Mol Biol. 2007 Mar 16;94(1-2):186–206. doi: 10.1016/j.pbiomolbio.2007.03.005

Figure 3.

Figure 3

A model of electrophoretic movement of morphogens through gap-junctional paths

(A) Schematically, a number of patterning systems can be visualized as a field of gap junctions terminating on a cell group at one end that establishes a strong polarization by ion exchange with the outside world. Gray level within the cells illustrate voltage gradient produced by pumps at the edge. (B) This results in an electrophoretic force that can, given realistic estimates of the physical parameters of cytoplasm and small molecules, result in a significant gradient of a small molecule across the cell field (yellow dots in panel A; this is now thought to be serotonin in the case of frog left-right patterning). (C) Importantly, mathematical analysis of the model illustrates that local gradients of GJC-permeable morphogens are thus set up within cells as well as across cell fields, potentially providing local directional cues.