| Cryomicroscope is an important tool in the research of low temperature biology and medicine. With the help of Cryomicroscope, the dynamic, micron-scale, visual investigation of freezing and thawing processes in living tissues and individual cells can be carried out.In this paper, principles of low temperature biology and medicine are briefly introduced. The historical development and current status of Cryomicroscope are reviewed. The functional requirement of this tool in the study of low temperature biology and medicine are analyzed. Following work has been carried out:A new Cryomicroscope with a convection stage is designed and built. It is heated with transparent electric resistance heater and is cooled with liquid nitrogen. The input of the heater is controlled with proportional-integral-differential (PID) logic. The flux of the cooling fluid is regulated by electronic expansion valve. For this Cryomicroscope, the maximum warming rate can reach 100℃/min, and the minimum cooling rate can reach 50℃/min. The accuracy of the temperature control is less than ±1.5℃The temperature distribution on the cryostage is analyzed with the numerical method. As phase change is involved, the Enthalpy Method is used. It is proved by the simulation that the temperature of samples can be estimated from the thermo-couple placed on the cover glass and the planar temperature distribution of the cryostage is approximately uniform.Software is designed to analyze the cryomicroscopic images. Following functions are included: area measuring, temperature marking, brightness analyzing, etc. Methods of segmentation of cryomicrscopic images are mainly discussed. Two methods are proved to be effective. One of them is based on a simple statistics of gray-gradient histogram. The other is based on the digital cellular neural network. The software is used in the experimental study on osmotic properties of human cord blood stem cell exposed to dimethyl sulfoxide.
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