Isolation of oval cells and transitional cells from the livers of rats fed the carcinogen DL-ethionine.

For the characterization of the metabolic and biologic properties of oval cells (i.e., cells emerging in the livers of rats treated with chemical carcinogens due to proliferation of bile ductular and/or duct cells) and transitional cells (i.e., cells having properties intermediate between those of oval cells and hepatocytes), these cells were isolated from the livers of Sprague-Dawley rats fed DL-ethionine for 4-5 weeks. The livers were dissociated into single cells by perfusion in situ with collagenase, and total cell suspensions were allowed to stand at unit gravity for 10 minutes to separate parenchymal (hepatocytes) from nonparenchymal cells. Nonparenchymal cells were centrifuged in linear gradients of Metrizamide (8-24% wt/vol), and 2-ml fractions were collected from the gradients. The cells in the fractions were defined by light microscopy, electron microscopy, and histochemical and immunofluorescence methods. A cell isolate was thus obtained consisting of Kupffer's cells (approximately 20%), bile ductular and/or duct cells and oval cells (approximately 30%), and transitional cells (approximately 50%). A twofold enrichment of bile ductular and/or duct cells and their derivatives was achieved over that found in the nonparenchymal cell fraction before isopyknic gradient centrifugation.