Production of normal piglets from hatched blastocysts frozen at −196°C

Improved Survival of Porcine Hatched Blastocysts Cryopreserved with Glycerol and Sucrose.

“…In the present study hatched blastocysts were also selected for freezing according to their size as the efficiency with which these can be frozen is known to decrease rapidly following hatching [4]. The use of this additional criteria may explain why the in vitro survival in all three groups in our study tended to be higher compared with previous studies [4,6] In the current study the addition of 0.25 M sucrose to the freezing media improved post-thaw survival compared with 1.5 M glycerol. A marked feature of this improvement was the increase in the percentage of blastocysts from 10 to 42% which had well expanded blastocoel with little or no visible sign of damage following thawing.…”

“…The post thaw survival of porcine embryos has been investigated by several workers previously (reviewed by Nagashima et al, 1994) [8]. In these studies 1.4-1.5 M glycerol has been used exclusively as a cryoprotectant for freezing at the peri-hatching stage [4][5][6][7][12][13][14]. In the present study hatched blastocysts were also selected for freezing according to their size as the efficiency with which these can be frozen is known to decrease rapidly following hatching [4].…”

In vitro technologies related to pig embryo transfer

“…Pig embryos are very sensitive to hypothermic conditions. Although there are reports on birth of live piglets after cryopreservation [38,46,51,66], porcine embryos are limited in their ability to withstand freezing and cryosurvival. This can be overcome using cytoskeletal stabiliser.…”

“…Research and initial application in the field of gene manipulation to improve growth and disease resistance, to generate foreign proteins in blood and milk, and to create tissues and organs for xenotransplantation need embryo transfer [7,18,19,35,71,95]. Other reproductive techniques to produce offspring like ovum pick up, and in vitro maturation and fertilization [14,64,68,87,110,113], generation of sexed embryos [88,89], cryoconservation of embryos [26, 41,46] and cloning [12,69,80,94] require also successful handling of embryo transfer technique. However, these reproductive techniques did not find practical application in swine production, yet.…”

Freezing of in Vivo Derived and in Vitro Pre-Cultured Porcine Blastocysts: Differences of the Cryoprotective Effect between Glycerol and Ethylene Glycol.

“…Except the delipated early cleavage stage embryos, successful cryopreservation of porcine embryos is confined to blastocysts at peri-hatching stage: expanded blastocyst to small (less than 300 µm) hatched blastocyst [5,6]. This condition, together with low embryonic survival following transfer [7][8][9], severely limits the practical application of this technology.…”