Penetration of nanoparticles into individual cells of the parenchyma. A) Phase contrast image showing the relative position of the cells carrying nanoparticles (squared) respect to the location of nanoparticle deposits in the pith cavity (arrows). B) TEM image of a region equivalent to the one squared in (A). Nanoparticles are electron dense, and appear surrounded by organelles. C) High magnification of the region squared in (B). Nanoparticles are aggregated. The cellular structures close to them show bright white inclusions. Bar in A = 20 μm; B and C = 2 μm.