Polarization of neurons growing on micropatterned substrates. (A) Hippocampal neurons cultured on micropatterned PLL and immunostained for axonal (Tau-1) and dendritic (MAP2) proteins. (B) Zoomed image of neuron in A. (C) Tau-1 immunostaining shows axons closely follow the patterned lines. (D) MAP2 immunostaining reveals that dendritic processes can be guided by the substrate, but are also regularly found extending on unpatterned glass. Pattern consists of intersecting 20 μm wide stripes spaced 420 μm apart.