Figure 2.

Routes of cell-to-cell communication in plant and animal cells. Simplified models for the transmission of signals between two plant (a) and animal (b) cells are shown. Signals are transported between cells via secretion of molecules (a and b) or vesicles (b), or direct physical cell-to-cell connections (PDs in a, and gap junctions and tunneling nanotubes in b). CW, cell wall; ER, endoplasmic reticulum; GJ, gap junction; PD, plasmodesma; PM, plasma membrane; TNT, tunneling nanotubes.