Compartmentalized devices allows to fluidically isolate two or more cellular populations, even when connected by microchannels. When using neurons, geometrical constraints due to microchannels allows neurites to grow and create functionnal synapses with distal neurons, both in a unidirectional or bidirectional way. Thanks to the fluidic isolation between compartments, a virus or protein can be applied to one cell population only, in an acute or chronic perfusion. Internalized molecules can be monitored for retrograde or anterograde transport, both by monitoring their presence on the remote compartment or within the axons themselves. Microchannels geometries can also be adapted to create gradients of secreted molecules or to allow migrating cells to pass from one compartment to the other.