Nomarsky light microscopy of rat hepatocyte cultures. Cells were incubated with Pb(NO3)2 (10 mM) or with conditioned medium (CM) from Kupffer cells incubated for 24 hours with Pb(NO3)2 (a) control hepatocytes (b) 24 hours incubation with Pb(NO3)2. Apoptotic hepatocytes are not present. (c) Apoptotic cells (arrows) are present when incubated with CM from Kupffer cells incubated for 24 hours with Pb(NO3)2. (d-e) Hepatocytes pre-incubated with 1 mM BSO for 24 hours, and subsequently incubated for 24 hours (d) or 48 hours (e) with Pb(NO3)2. Deprivation of GHS leads to apoptosis also upon incubation with Pb(NO3)2. Arrows indicate apoptotic hepatocytes that are characterized by shrinkage in volume, round shape, very condensed cytoplasm and dark nucleus. Bar = 10 μm.