Light micrographs of rat liver sections, (a, b) haematoxylin eosin staining and (c, d) apoptotic detection by TUNEL staining, from (a, c) animals 5 days after a single Pb(NO3)2 injection and animals 5 (b) and 3 (d) days after Pb(NO3)2 injection 24 hours GdCl3pre-treated. (a) Apoptotic hepatocytes (arrows) show round shape, condensation of chromatin and cell shrinkage. One fragmented apoptotic hepatocytes (arrowhead). (b) The GdCl3 pre-treatment reduces the hepatocytes apoptosis. In (d), the number of TUNEL-positive nuclei (arrows) in hepatic parenchyma is much lower than 5 days after a single Pb(NO3)2 injection (c, arrows). Bar = 10 μm.