Vitrification of bovine matured oocytes and blastocysts in a paper container.

Abstract

In the present study, we aimed to determine the applicability of a paper container for the vitrification of invitro matured (IVM) bovine oocytes. In experiment 1, IVM oocytes were exposed to vitrification solution (20% dimethylsulfoxide (DMSO), 20% ethylene glycol (EG), and 5mol/L sucrose), using a two-step method, for 30s; loaded onto either a paper container or Cryotop; and stored in liquid nitrogen. No significant difference (P<0.05) in the survival and blastocyst formation rates after invitro vitrification was observed between the paper container and Cryotop. In experiment 2, IVM oocytes were exposed to either a two- or three-step vitrification solution. The three-step vitrification solution was not significantly different from the two-step solution in terms of oocyte survival, cleavage and blastocyst rates. In experiment 3, invitro produced blastocysts were graded according to the manual of the International Embryo Transfer Society (grades 1 and 2) and vitrified using the two- and three-step methods. For grade 2 blastocysts, the three-step method showed significantly higher (P<0.05) survival and hatched blastocyst rates than the two-step method, whereas for grade 1 blastocysts, no significant difference was observed. In conclusion, the paper device and three-step technique are suitable for oocytes and embryo vitrification.