Mitochondrial DNA deletion in granulosa and cumulus oophorus cells

The incidence of the 4,977-bp deletion in mitochondrial DNA (Delta mtDNA(4977)) in 73 pairs of granulosa and cumulus oophorus cells was studied with polymerase chain reaction (PCR), and was significantly higher in granulosa cells (GC) (67/73, 91%) than in cumulus oophorus cells (17/73, 23.3%), independent of the donors' age. In the cumulus oophorus cells, the oocyte morphology, the ooplasma diameter, and the proportion of oocytes fertilized normally were comparable between those with and without Delta mtDNA(4977); whereas the oocyte diameter and the zona thickness were significantly higher in those with Delta mtDNA(4977).