1989 Volume 35 Pages 97-108
The aim of this article is to introduce a part of the current study on frozen storage of pig embryos which have not yet been successfully preserved at -196℃. The hypothesis of the present study was that low temperature injury would be the primary cause of freezing injury for pig embryos. With the intention of avoiding low temperature injury, egg yolk at the proportion of 5%(v/v)and 10%(v/v) was added to solutions for 4℃ exposure experiment and for freezing experiment (-196℃). Embryos of the range from early blastocyst to hatched blastocyst were collected surgically from several breeds on Day 5 to 6 (Day 0=estrus). In the experiment of 4℃ exposure, 10 out of 21 embryos developed in vitro when 5% egg yolk was added to PBS supplemented with 10% fetal calf serum. In the experiment of freezing, 7 out of 14 embryos, which were frozen and thawed by the standard procedures for cow embryos in the presence of 10% glycerol and 10% egg yolk, obviously continued to maintain the viability after 24 h in vitro. These results suggest that low temperature injury may be one of the cause of freezing injury for pig embryos, and that the injury may result from cell membrane, especially from phospholipid bilayer. In this study, no pregnancy was obtained after transferring the frozen-thawed embryos to recipient pigs.
