A biocompatible substrate for cell adhesion, differentiation, culture and/or growth, has an arrangement of topographical features arrayed in a pattern based on a notional symmetrical lattice in which the distance between nearest neighbor notional lattice points is C and is between 10 nm and 10 .mu.m. The topographical features are locally mis-ordered such that the centre of each topographical feature is a distance of up to one half of C from its respective notional lattice point.