ANTIOXIDATIVE CAPACITY OF PREIMPLANTATION EMBRYO CULTURE-MEDIUM DECLINES FOLLOWING THE INCUBATION OF POOR QUALITY EMBRYOS

Total antioxidative capacity (TAC), a measure of overall free-radical scavenging potential, was determined by enhanced chemiluminescence in preimplantation embryo culture medium (PECM; pre-equilibrated Ham's F- 10 medium supplemented with 7.5% patient's serum). Changes were evalua ted in PECM TAC following a 24 h incubation of 66 single human embryos , as was TAC of patient's serum alone. The PECM TAC averaged 8.1% of t he same patient's blood serum TAC. The percentage decline of PECM TAC over an incubation period of 24 h ranged from 0.9 to 41.7%, with a med ian of 5.5%. The decline in PECM TAC in different embryo quality group s was also studied. Embryos were categorized as 'good', 'fair' or 'poo r' according to a scoring system based on an assessment of both the mo rphological appearance and developmental speed of the embryos. Incubat ion of poor quality embryos was associated with a decline in TAC, whic h was significantly higher than that observed in 'good' and 'fair' emb ryos. The findings suggest that impaired embryo development may be ass ociated with an increased generation of reactive oxygen species by the embryo.