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Figure 3.47. Sketch of a transverse section of a young root showing three proposed pathways of ion and water flow across roots. 1. Apoplastic, via cell walls. 2.  Transmembrane (transcellular), via cytoplasm within cells and crossing membranes via efflux and influx membrane transporters. 3. Symplastic, via cytoplasm all the way, crossing cell walls via plasmodesmata. (Drawing courtesy B. Berger, based on Plett and Moller 2010). Note that at this stage the endodermis is not suberised and has just a Casparian strip (red). Deposition of suberin in the endodermal wall, and the development of an exodermis, will restrict the apoplastic and transcellular pathways.