To predict the optimal cryopreservation protocol for biological cells, a new intracellular ice formation model was developed by incorporating the nonideality into the intracellular solution. Compared with the ideal solution model based on the modified Mazur’s water transport equation, the new model further coupled Fahy’s water transport equation, ice nucleation, and the diffusion-limited ice growth theory. The new model was then used to study the freezing process of mouse oocyte in the presence of glycerol as a cryoprotective agent. Through the comparative analysis of the influence of cooling rate and initial glycerol concentration on the intracellular solution volume and the crystallized volume fraction under these two models, it was found that the predictions by these two models had significant difference at low cooling rate, while they are consistent at high cooling rate.

Key words: intracellular ice formation, vitrification, nonideal solution