Effect of leukemia inhibitory factor on bovine embryos produced in vitro under chemically defined conditions.

The objective of these experiments was to assess putative embryotrophic effects of leukemia inhibitory factor (LIF) on bovine preimplantation development in chemically defined media. Recombinant human LIF was added to embryo culture media at a concentration of 100 ng/ml. When added for culture of morulae LIF had no positive effect on the proportion of embryos reaching the blastocyst stage. However, LIF significantly reduced development to the blastocyst stage when added for culture of 4-cell stage embryos (P<0.05). In contrast, a positive effect was found for progression of blastocyst development. In vitro blastocyst hatching rates were significantly improved in the presence of LIF (P<0.02). Number of total cells and of inner cell mass (ICM) cells were increased in LIF-treated blastocysts. In vitro survival of frozen-thawed blastocysts was not improved by adding LIF to morula stage embryos before cryopreservation. The pregnancy rate after direct transfer of cryopreserved LIF-treated embryos was not different from that for untreated control embryos. Data indicate that addition of LIF has no major beneficial effect on bovine embryos produced in these chemically defined conditions.