Effect of reduced concentrations of glycerol and various macromolecules onthe cryopreservation of mouse and cattle embryos

The effect of different macromolecules [bovine serum albumin (BSA), Pluroni c F-68, (ET surfactant), or sodium hyaluronate (SH)] on postthaw survival o f mouse morulae and in vivo- and in vitro-derived bovine blastocysts frozen in 10, 5, or 1% glycerol solutions was investigated. Embryos were equilibr ated with cryoprotectant solution at 25 degrees C for 10 min, seeded at -5 degrees C, cooled at 0.5 degrees C/min to -35 degrees C, and plunged into l iquid nitrogen. Embryos were thawed in a 35 degrees C water bath. glycerol was removed with 0.6 M sucrose at 25 degrees C for 5 min, and postthaw viab ility was evaluated after 1, 24, and 48 h in culture. The addition of BSA s upplementation improved postthaw survival of mouse morulae frozen in 5% gly cerol, but nor in 10% glycerol. All three macromolecular supplements were e ffective in increasing survival of mouse morulae in 5% glycerol but only BS A and SH were effective in increasing postthaw survival of in vivo- and in vitro-derived bovine blastocysts. None of the macromolecular supplements im proved postthaw survival of embryos frozen in 1% glycerol. (C) 2000 Academi c Press.