Effects of gas atmosphere, platelet-derived growth factor and leukemia inhibitory factor on cell numbers of rabbit embryos cultured in a protein-free medium.

While culture conditions for embryos have improved, development in vitro is not equivalent to in vivo growth. Platelet-derived growth factor (PDGF), mouse (mLIF) or human (hLIF) leukemia inhibitory factor and 10% fetal bovine serum (FBS) added to protein-free culture medium, as well as two gas atmospheres were evaluated for their effect on rabbit embryo development. Adding PDGF, mLIF or hLIF to the culture medium did not result in detectable differences in total cell number for blastocysts. The culture of rabbit embryos under a gas atmosphere of 10% CO2:5% O2:85% N2 resulted in improved total cell numbers (P < 0.01) for blastocysts compared to those developing under 5% CO2:95% air (230 vs 159, respectively). Supplementing RD (RPMI-1640 and Dulbecco's MEM, 1:1) medium with 10% FBS improved the number of total cells (264 vs 155) and inner cell mass cells (71 vs 47). These results indicate that when defined culture conditions promote a high proportion of two-cell embryos developing into blastocysts, the addition of certain growth factors did not have a detectable beneficial effect, while 10% FBS improved culture conditions.