This study was designed to investigate the ability of porcine follicular fluid to increase the efficiency of fertilization of cumulus-free mouse oocytes .Porcine follicular fluid(pFF)was fractionated by ultracentrifugation,and termed Top ,Second, Third,Bottom.The addition of Top fraction to the sperm preincubation medium and the fertilization medium raised the fertilization rate significantly and dosedependently(10% Top:11%,20% Top:25%,P<0.01),while the others exhibited no effect.pFF Top

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... n also increased the number of capacitated spermatozoa (control:21%,Top:36%,P<0.05)as revealed by chlortetracycline assay after 2h preincubation.Additionally,the length of time necessay for zona lysis with chymotrypsin greatly decreased.These results indicated that pFF might facilitate sperm capacitation and prevent hardening of zona pellucida,resulting in increasing efficiency in the fertilization of cumulus -free mouse oocytes.