SHORT-TERM DIETHYLNITROSAMINE-INDUCED OVAL CELL RESPONSES IN 3 STRAINS OF MICE

The oval cells of the liver have been identified as target cells of ch emical carcinogens during rat hepatocarcinogenesis and are believed to act as liver stem cells. In this study mice (strains C3H/EJ (C3H), C5 7/BL6J (C57) and hybrid B6C3F1 (F1)) were sacrified at 1, 3 and 7 days after administration of a single dose of the carcinogen diethylnitros amine (DEN), and histopathological studies of oval cells were evaluate d using Haematoxylin and Eosin (H&E), Picro-Mallory (P-M), alpha-fetop rotein (A-FP) and glutathione S-transferase placental form (GST-pi) st aining techniques and electron microscopy (EM). Increased oval cell pr oliferation was observed as soon as one day following exposure of the mice to DEN, in a manner consistent with C3H and C57 mice exhibiting h igh and low susceptibility to DEN respectively, with hybrid F1 mice be ing intermediate in DEN sensitivity. This analysis indicates that, in mice, oval cells are target cells at very early stages of liver carcin ogenesis and supports the notion that oval cells are potential liver s tem cells.