“…The use of a water circulating system for temperature control was preferred to an electrical heating element (see, for example, Lowndes & Hallet, 1986) because the former also provides the opportunity to cool the central well to below room temperature. Similar microperfusion chambers tend to be constructed such that the glass coverslips are sealed in position with wax or petrolatum (Pomerat, 1951;Christiansen et al, 1953;Toy & Bardawil, 1958;Cruikshank et al, 1959). Others use a sealing similar to that used here (Buchsbaum & Kuntz, 1954;Richter & Woodward, 1955;Sykes & Moore, 1959;Thomas & Cramer, 1966;White, 1966;Poyton & Branton, 1970;Dvorak & Stotler, 1971), but none of these allows the temperature of the cell compartment to be controlled.…”