Fig. 1. Representative images of confocal laser scanning microscopy of DNA fragmentation in cumulus cells, as detected by TUNEL (green label). All cell nuclei are also stained with propidium iodide (red). Positive control DNAse 1-treated OOX showed very strong apoptotic staining (99%) (A), negative control did not reveal any apoptotic signals (0%) indicating specific labelling (B), expanded COC after culture with low apoptotic labelling (9%) (C), compared with OOX with higher apoptotic labelling (35%) (D). Light micrograph of an unexpanded intact COC before culture (E) and a denuded oocyte (F), generated by the mechanical removal of cumulus cells from a COC.