Abstract: The stage assembly for use in a microscope comprises a mechanical stage having an opening therein, a stage support plate having an opening therethrough, a support for supporting the stage support plate in the opening in the mechanical stage, a device for heating/cooling or warming the stage support plate mounted to the stage support plate, a specimen chamber/coverslip assembly mounted on the stage support plate above the opening therethrough, a perfusion fluid preheater/cooler assembly mounted on the support plate, a perfusion fluid tubing extends through the preheater/cooler assembly and to a specimen chamber in the specimen chamber/coverslip assembly, and a conduit for withdrawing perfusion fluid from the specimen chamber.

Abstract: An apparatus for maintaining thermal control of the temperature of a microscope stage is provided. A thin copper plate is arranged with a non-inductive serpentine heating element pattern controlled by a proportional power controller. A thermistor temperature sensing device is arranged to sense the temperature near the specimen container and to provide the sensed data to the controller. Proportional power control is accomplished by varying the ratio of "ON" and "OFF" power cycles as the desired temperature is approached.