Microchannels were produced using a photolithographic technique to pattern polyimide walls (11 microm in height and 20-60 microm in width) onto a planar glass substrate. PC12 cells were seeded onto patterned surfaces. After 3 days of culture in NGF supplemented medium cells were viable and extended neurites. Culture in microchannels influenced the direction of neurite growth (theta Orientation) and the complexity of PC12 cell architecture including neurite length (L(Neurite)), the number of neurites emerging per cell (N(Neurites)), and the angle at which neurites emerged from the cell soma (theta Soma). In microchannels neurites oriented parallel to channel walls and the complexity of neuronal architecture was reduced. Both of these effects were strongest for cells located in channels 20-30 microm wide. Within each channel the magnitude of the effect on orientation and architecture was inversely proportional to the distance of the soma from the channel wall. Microtubule and actin filament mobility within the cytoplasm may underly effect on neurite orientation and cell architecture. By manipulating channel width the overall direction of neurite growth and the complexity of neuronal architecture was controlled. Results from these studies will be applied towards the development of biomaterials for microfluidic platforms and drug discovery studies and in neural regeneration research-two applications that would be significantly improved given the ability to control neurite orientation and the complexity of neuronal architecture.