Fetal development after transfer is increased by replacing protein with the glycosaminoglycan hyaluronan for mouse embryo culture and transfer.

The effect of macromolecules on mouse embryo development and viability after culture in sequential media was investigated. It was found that high rates of viable blastocysts could be obtained in the absence of any macromolecule. Blastocyst cell numbers were increased when bovine serum albumin was present in the culture medium, although this benefit was not manifest after blastocyst transfer. Rather, the highest rates of implantation and fetal development after blastocyst transfer were observed when hyaluronan was the macromolecule in the culture media. Subsequent analysis revealed that the beneficial effects of hyaluronan were due to its presence in the transfer medium. As the highest cell numbers and hatching rates obtained in this study occurred when both serum albumin and hyaluronan were present in the same medium, it is proposed that embryo culture media should contain both serum albumin and hyaluronan, while the transfer medium need only contain hyaluronan.