Cryopreservation of bovine blastocysts obtained by intracytoplasmic sperm injection.
The freezability and survivability of zona-intact and zona-free (hatched) bovine blastocysts obtained by intracytoplasmic sperm injection (ICSI) were assessed. Day 7 or 8 blastocysts were cryopreserved by slow freezing using 1.5 M glycerol and 0.2 M sucrose. Embryos were exposed to solutions in a 2-step procedure at room temperature and frozen in a programmed cell freezer. Blastocysts that re-expanded within 6 h of post-thaw culture were considered viable. The cleavage, morula and blastocyst development rates after ICSI were 52.4 (131/250), 39.7 (52/131), and 24.4% (32/131), respectively. Blastocyst stage embryos were randomly divided into 2 groups. The first group of embryos was frozen with their zonae intact, while the second group was allowed to hatch from their zonae during the additional 18 h culture, after which they were frozen. The data showed that more Group 2 blastocysts (14/16, 87.5%) than Group 1 (12/16; 75.0%; P<0.05) survived, and more zona-free bovine blastocysts frozen with glycerol as the cryoprotective agent (CPA) than zona-intact blastocysts after slow freezing retained their viability.
Keskintepe
L
L
Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta 30912-2600, USA. Leventk@immag.mcg.edu
Brackett
B G
BG
D000818:Animals; D001755:Blastocyst; D002417:Cattle / Q000196:embryology*; D015925:Cryopreservation / Q000662:veterinary*; D005260:Female; D008297:Male; D020554:Sperm Injections, Intracytoplasmic / Q000662:veterinary*