Our mouse hepatocytes are prepared using the same careful isolation and cryopreservation techniques as our human lots. Characterization methods of cryopreserved hepatocytes include ECOD, 7-HCG and 7-HCS for phase I and phase II enzyme activities. We also closely monitor cell morphology, attachment efficiency, monolayer confluency (plateable cells) and viability stability over time for both fresh and cryopreserved hepatocytes.