Asymmetric confinement for defining outgrowth directionality Directional connectivity is required to develop accurate in vitro models of the nervous system. This research investigated the interaction of neuronal outgrowths with asymmetric microstructured geometries to provide insights into the mechanisms governing unidirectional outgrowth bias. The structures were designed using edge-guidance and critical turning angle principles to study different prohibitive to permissive edge-guidance ratios.