This unique and versatile Brain/Tissue Slice Chamber System offers the investigator two in vitro methods of studying a thin slice of tissue, which is bathed by perfusates of interest. The BSC-HT (Haas Top) is an interface-type chamber in which one cut surface of the slice is wetted by a perfusing solution while the other surface is kept moist by a humidified gas mixture. The BSC-ZT (Zbicz Top) is a chamber in which solutions flow transversely to fully submerged slices. Each top unit allows for rapid changeover of fluids which are being investigated and both provide for excellent access to the slices for electrophysiological recording or other observations.