Human granulosa cells after ovulation induction show caspase-independent cell death

It has become clear that apoptosis is an essential part of normal folliculogenesis and that granulosa cells in particular demonstrate intense cellular activity as well as programmed cell death. Although the entire mechanism of apoptosis appears to be conserved through many species, it now becomes clear that different cells may use different pathways within this system. We examined human granulosa cells after ovulation induction during an in vitro fertilization procedure to study apoptosis in this particular situation. We demonstrated a loss of cytokeratin staining as granulosa cells differentiate. We also detected that granulosa cells with apoptotic morphology did not stain for terminal deoxy-UTP nick end labeling and we showed the absence of immunoreactivity for caspase-cleaved cytokeratin, caspase-cleaved poly-ADP-ribose polymerase and caspase-cleaved caspase-3 in apoptotic granulosa cells. These data provide strong arguments for a caspase-independent cell death mechanism in human granulosa-lutein cells.