Liver injury and apoptosis are higher in the allogeneic grafts vs. the syngeneic grafts. Three pairs of OLT were performed (Lewis to Lewis: L-L; Lewis to DA: L-DA; DA to Lewis: DA-L) for various time points. (A, B) Sera were harvested for ALT/AST measurement. (C) Liver tissues were harvested and stained with TUNEL assay to examine apoptosis. Representative photomicrographs are shown in the top panel (arrows indicate TUNEL+ hepatocytes). The number of TUNEL+ hepatocytes was counted and shown in the bottom panel. Values in panels A-C are shown as means ± SEM (n=3 pairs on day 1; n=5 pairs on day 2 and 5; n=6 pairs on day 3, 4, and 7). *P<0.05, **P<0.01, ***P<0.001 compared with values from corresponding L-L syngeneic grafts.