The oocyte, inside the growing antral follicle, is surrounded by cumulus cells (CC). CC are specialized granulosa cells connected to the oocyte by transzonal processes and gap junctions that allow two-way communication with the oocyte (12). The oocyte can provide growth and metabolic signals to the CC while ATP and mitochondria from cumulus cells may supplement energy in the oocyte transiently through the transzonal processes between CC and the oocyte. In addition, these connections facilitate the passage of nutrients such as pyruvate and coenzyme Q10 (coQ10) for oocyte mitochondrial function from the CC. CoQ10 may be particularly important for normal oocyte development including resumption of meiosis and subsequent embryo development since it is a major component of the electron transport chain, responsible for mitochondrial ATP production. We have demonstrated in a mouse model that CC number decreases through apoptosis with aging (13, Ben-Meir et al, unpublished) and that gene expression for synthesis of coQ10 also is reduced as animals age (14). Both findings will result in decreased mitochondrial energy production with aging. We hypothesized that supplementation of aging mice with coQ10 might restore normal reproductive function by improving nuclear spindle and chromosomal segregation during meiosis and mitosis and increase the energy for embryo cleavage to the blastocyst stage. Our results in 52-week-old mice confirmed this hypothesis with restoration of normal litter size compared to 10-week-old control mice (14). Mitochondrial function was impaired in old mice and restored partial by coQ10 supplementation. We followed this animal study with a randomized clinical trial of coQ10 or placebo for 2 months prior to IVF in women over the age of 38 years. This trial was stopped after two years before reaching adequate power because of poor enrolment but did show a non-significant reduction in polar body biopsy assessment of oocyte aneuploidy from 62.8% in the control group to 46.5% in the coQ10 group (15).