Fig. 6. Internalization of negatively charged nanogold for 1 hour. (a) Accumulation of probe was not observed in the tip region, in which a limited number of vesicles was labelled (arrows). (b-e) Internalization was not observed in the subapical region (b-d) or in the region far from the tip (e). (b,d,f) Negatively charged nanogold was never observed within membranous organelles such as the ER or Golgi bodies (G). Bars, 0.5 µm (a-e), 1 µm (f).