Activation & Signal Transduction
In the
blastoderm (1), a single cell may be turned on to secrete a protein
signal (2). Other cells with receptors for this signal (3) are turned
on to a greater or lesser extent (4), depending on their distance from
the signal source (5). Thus the expression state of each cells depends
on its position in a complex field of signals from other cells.
All text material © 2007 by Steven M. Carr