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FSA MINIPOSTER SESSIONFERTILISATION RATE AND THE DURATION OF~SPERM-EGG lNTERACTIONA. Lakmaker, J.D. Stanger and K. Stevenson.Lingard Fertility Centre. Merewether NSW.Recent studies have suggested that decreasing the duration ofspenn-egg interaction promotes embryo quality and pregnancyafter cryostorage. The implication ofthis is that prolonged co-incubation ofgametes may have detrimental effects on embryoquality. Whether this is because ofthe accumulation ofwaste metabolites from spermatozoa or because ofnegative aspects ofzyg~te culture in glucose c?n~g media has not been explored. While glucose is required for gpenn motility, mouse embryostudies have found a negative nnpact on early embryo metabolism.Before reducing the duration ofinteraction, it seemed reasonable to confinn that fertilisation rates are not effected. Thereforein series ofpatients undertaking IVF [but not ICSI] where 6 or more ova were recovered, the duration ofgamete interactionwas equally split between 2 hours and 16 hours [paired trial]. The oocyte-coronal cell mass was removed with a largemicropipette and transferred to another well containing the same media as the 16 hour extended culture. Both groups wereexamined at 16 hours for evidence offertilisation and embryos with 2 pronuclei were pooled for further culture. Thefertilisation environment comprised RTF [Irvine] with 10mg/ml HSA [IVF Sciences] as 100ul microdrops containingspennatozoa ~der mineral oil ~VF Sci.ences]. Spermatozoa were initially collected 3 hours before insemination [group A:2hours preparation and 1 hour premcubation] and later at 4-5 hours before insemination [Group B:2 hours preparation and 2-3hours preincubation] and diluted to approximately 400,OOO/ml. All ova were collected between 7:00am and 8:30 am andadded t? the preincubated spermatozoa at 14:00 hours. Fertilisation rates [%] were compared using Students t-test -pairedcompanson.Preincubation [Hrs]* P