Abstract
The purpose of this study is to evaluate whether the thermophysical properties of cells reflect the freezing process, and can be used as indices of cryopreservation. Medaka embryo (Oryzias latipes) was selected as the biological material for this study. The effective thermal conductivity of Medaka embryos was measured using the self-heated thermistor technique developed by Balasubramaniam and Bowman (1977). The test chamber (8×8×12 mm) was covered with insulating material, and a thermistor bead of 2.5 mm in diameter installed in the bottom. The effective thermal conductivity was measured at 6, 0, -4, -10, -15 and -20℃ with a cooling rate of 1℃/min, and the viability of the embryos was evaluated by the hatching rate. The effective thermal conductivity is closely correlated with the hatching rate, increasing as the their hatching rate decreased. Thus the thermophysical properties of biological materials can be used as indices with which to evaluate the freezing process.
