Podatnosc zarodkow owcy na witryfikacje w zaleznosci od ich stadium rozwojowego

Surgically obtained early sheep embryos collected at morula, blastocyst, expanded blastocyst or hatching/ hatched blastocyst developmental stages were subjected to vitrification. The experiment was carried out by the traditional vitrification method, employing 0.25 ml insemination straws as carriers of embryos. The vitrification medium (VM) based on a modified phosphate-buffered solution (PB1) containing 3.0 g/L bovine serum albumin consisted of 1,2-propanediol, glycerol and sucrose (2.72 M, 1.36 M and 1.0 M - respectively). Embryos (each stage separately) were loaded into straws after 7-10 min of saturation in an equilibration solution (without sucrose). After 1 min period of saturation in VM embryos were plunged into liquid nitrogen. After warming, embryos were cultured in vitro and/or were surgically transferred to a surrogate mother for survival examination. Of 71 embryos tested, only 13 (18.3%) revealed development in vitro. The highest survival rate was observed in the most advanced group of embryos. Of 10 hatching/hatched embryos 6 (60%) survived (reexpanded). Three lambs were born after the transfer of 3 embryos from this group.