Objective To explore a technique to improve the efficacy of generation of transgenic sheep by injection of lentivirus into the perivitelline space of oocytes.Methods Recombinant EGFP lentivirus was injected into the perivi-telline space of oocytes.The growth status and gene expression of oocytes at different stages of embryonic development were assessed to analyze whether the injection doses of the lentivirus or the skill of different operators influence the embryonic de-velopment.Results(1) The lentivirus ...