Presence of nanoparticles in adjacent parenchymatic cells. A) Bright field image, toluidine blue staining of a section of the stem showing cells carrying nanoparticles (squared area) between two vascular cores (VC). The nanoparticle deposits in the cell wall facing the pith cavity (PC) appear labelled with arrowheads. B) Phase contrast image of a section consecutive to the one showed in (A), with a detail of the region squared in (A). Dark material appears in the cell cytoplasm surrounded by dense structures. The surrounding cells do not show such a dense cytoplasm. C) TEM image showing a detail of a nanoparticle aggregate inside one of the cells showed in (B) which is labelled by (*). Bar in A and B = 100 μm; C = 1 μm.