Fig. 1. Neural intermediate filaments move bidirectionally throughout all regions of nerve cells. (A) Differentiated PC12 cells expressing GFP-peripherin show that particles and squiggles, the precursors to long IF, are present in the peripheral regions of cell bodies. (B) These structures can be visualized in the neurites of live cells expressing GFP-peripherin after photobleaching (arrows denote the bleached region). (C) Peripherin particles can also be observed throughout the central and peripheral domains of the growth cones of nontransfected PC12 cells following fixation and staining for peripherin (green) and actin (red). (D) A series of images taken from a live PC12 cell expressing GFP-peripherin. The peripherin particle (see arrows) moved at rates of up to 0.58 µm/s and reversed directions in a region of the cell body during the observation period. Bars, 5 µm (A-C) and 2 µm (D).