Epithelial-like cells derived from livers of infant Fischer rats are maintained in culture, either continuous or after frozen storage. Ultrastructural alterations produced by long term culture and frozen storage are being examined. Transformation of the cells to a malignant form by various chemical carcinogens is being studied. BIBLIOGRAPHIC REFERENCE: Idoine, J. B., Elliott, J. M., Wilson, M. J. and Weisburger, E.K.: Rat liver cells in culture: effect of storage, long-term culture, and transformation on some enzyme levels. In Vitro 12: 541-543, 1976.