title: Laser-assisted vitrification of large equine embryos.
abstract: The major difficulty in providing the benefits of embryo cryopreservation for equine agriculture is the mismatch between the optimal embryo age for collection from the mare (7-8 days after ovulation was detected) and the optimal age for freezing under current methods (6.5 days after ovulation). To overcome this limitation, we tested a method to enhance penetration of cryopreservative across the capsule and trophoblast of day 7 and 8 embryos combined with rapid freezing by vitrification. Six small embryos (<300 μm in diameter) were collected on day 6-7 after ovulation and twelve larger embryos were recovered on day 7-8. In the treatment group, replacement of blastocoelic fluid with cryopreservative solution was facilitated by a laser system used to create a small opening in the embryonic capsule and trophectoderm. All embryos were vitrified using a CryoLeaf freezing support. After recovery from freezing and embryo transfer, three of four small untreated embryos (<300 μm in diameter, 75%) and four of nine large blastocysts in the treatment group (>300 μm in diameter, 44%) resulted in a vesicle as detected by ultrasonography approximately one week after transfer. However, only one recipient mare was still pregnant on day 23, and she delivered a live foal. Further investigation is required to determine why most of the embryos in this experiment were lost between day 13 and day 23 of gestation.
authors.affiliation: Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA, USA. jakob.scherzer@bayern-genetik.de
authors.forename: J
authors.initials: J
authors.lastname: Scherzer
authors.forename: C
authors.initials: C
authors.lastname: Davis
authors.forename: D J
authors.initials: DJ
authors.lastname: Hurley
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D046149:Embryo Culture Techniques / Q000662:veterinary; D004624:Embryo Transfer / Q000662:veterinary; D005260:Female; D006736:Horses / Q000196:embryology*; D007834:Lasers; D011247:Pregnancy; D058989:Vitrification