A fluidic culture device (100) comprises a substrate (101) of transparent polymer material with an open culture chamber (110) in the form of a hollow in a bottom surface (102) of the substrate (101). Open fluid channels (120, 130) flank the culture chamber (110) and have inlets (140, 150) and outlets (160) in a top or end surface (104, 106) of the substrate (101). Removable channel plugs (180, 190) are temporarily arranged in the portions of the fluid channels (120, 130) adjacent the culture chamber (110) to prevent culture matrix material poured into the culture chamber (110) from entering and blocking the fluid channels (120, 130). When assembling an operational culture system (230), a biological sample (210) is introduced in the culture matrix (200) and the channel plugs (180, 190) are removed. A transparent cover disk (220) is reversibly attached to the bottom surface (102) to enclose the culture chamber (110) and the fluid channels (120, 130). A gradient is established over the culture chamber (110) by entering fluids having different concentrations of a substance in the fluid channels (120, 130).