Perpendicular contact guidance of CNS neuroblasts on artificial microstructures

Rodent CNS neuroblasts show parallel and perpendic-ular contact guidance behaviors on aligned neurite bun-dles in microexplant cultures (Nakatsuji, N. and Nagata, I. (1989) Development, 106, 441-447; N. I. and N. N. (1991) ibid., 112, 581-590). To test the hypothesis that the physical surface structure of the neurite bundle causes the perpendicular contact guidance, we cultured dissociated neuroblasts on quartz plates on which grat-ing-like microstructures were fabricated by lithographic techniques. Various types of CNS neuroblasts, but not PNS neurons, oriented their processes and migrated both perpendicular and parallel to the axis of the microstructure. Perpendicular orientation was fre-quently observed when the microstructured grooves had depths between 0.3 m and 0.8 m and a width of 1 m, which roughly mimics a tightly aligned neurite bundle. Thus, CNS neuroblasts have the ability to extend their processes and migrate perpendicular to aligned surface microstructures.