COMPARISON OF THE SURVIVAL RATE OF IN-VIVO AND IN-VITRO PRODUCED BOVINE EMBRYOS AFTER A SIMPLE VITRIFICATION PROCEDURE

Bovine in vivo and in vitro produced embryos at different stages of de velopment were exposed to a vitrification procedure which has already resulted in a high in vitro survival rate for bovine in vivo compact m orulae-early blastocysts. The vitrification solution consisted of 7.15 M ethylene glycol, 2.5 mM ficoll and 0.3 M sucrose (EFS solution). Co mpact morulae-early blastocysts, blastocysts and expanded blastocysts were transferred into straws and immersed into liquid nitrogen after 3 minutes exposure to EFS solution. The average post-thaw survival rate for the different stages of in vivo and in vitro embryos was 66.7 %, 15 %, 10 %, and 0 %, 4.8 % and 10.5 %, respectively. The overall survi val rate of the in vivo and in vitro embryos was 38.6 % and 5 %, respe ctively. It is concluded that in vivo derived embryos are more resista nt to vitrification and their average survival rate is significantly h igher than of in vitro embryos (p < 0.05). The survival rate also depe nds on the stage of embryonic development. In vivo produced compact mo rulae-early blastocysts have a significantly higher survival rate than blastocysts and expanded blastocysts (p < 0.05). There exists also a significant difference between the average survival rate of compact mo rulae-early blastocysts and expanded blastocysts produced in vitro (p < 0.05).