(a) Neuronal cluster on the Si spikes area. (b) Detail corresponding to white lined inset of (a), showing a long neurite that has attached and grown over the spikes. (c) Detail corresponding to white lined inset of (b), showing protrusions of neurolemma growing over and engulfing the top of the spikes. (d) Detail corresponding to black lined inset of (a), showing the 3D web of cytoplasmic processes growing along the direction vertical to the culture plane. The arrows indicate how multiple processes may initiate from one neurite. Reproduced with permission from E. L. Papadopoulou et al., Tissue Eng Part C Methods 16, 497 (2010). Copyright 2010. Mary Ann Liebert.