Molecular gradient along the axon pathway is not required for directional axon growth.

We show that axon guidance of embryonic hippocampal neurons is promoted by pathways of a decapeptide (RDIAEIIKDI) derived from a neurite outgrowth domain of the gamma1 chain of laminin-1. This guidance is directly dependent on: (1) a concentration difference of the decapeptide between the peptide pathway and its surrounding areas, and (2) the optimal surface geometry of the decapeptide pathway. These results indicate that axon guidance of central neurons may proceed along a preferred substratum pathway without a concentration gradient of the guiding molecule along this pathway, or without a repulsive molecule next to the axon pathway.