title: In-straw cryoprotectant dilution of IVP bovine blastocysts vitrified in hand-pulled glass micropipettes.
abstract: The aim of this study was to determine the influence of two ethylene glycol-based vitrification solutions on in vitro and in vivo survival after in-straw cryoprotectant dilution of vitrified in vitro-produced bovine embryos. Day-7 expanded blastocysts were selected according to diameter (> or = 180 microm) and osmotic characteristics and randomly assigned to one of three groups (i) VSa: vitrification in 40% EG+17.1% SUC+0.1% PVA; (ii) VSb: vitrification in 20% EG+20% DMSO; (iii) control: non-vitrified embryos. Vitrification was performed in hand-pulled glass micropipettes (GMP) and cryoprotectant dilution in 0.25 ml straws after warming in a plastic tube. Embryo viability was assessed by re-expansion and hatching rates after 72 h of IVC and by pregnancy rates after direct transfer of vitrified embryos. No differences in re-expansion rates were observed between vitrified groups after 24 h in culture (VSa=84.5%; VSb=94.8%). However, fewer VSa embryos (55.2%, P<0.05) hatched after 72 h than the VSb (75.8%) and control embryos (80.0%). To evaluate in vivo viability, vitrified embryos (VSa=20; VSb=21) were warmed under field conditions and individually transferred to synchronous recipients. Pregnancy rates (day 60) were similar between groups (VSa=20%; VSb=19%). Greater hatching rates occurred after 72 h of IVC for EG+DMSO than EG+SUC+PVA vitrification solutions. However, using a GMP vitrification container and in-tube warming, both solutions provided similar pregnancy rates after the in-straw cryoprotectant dilution and direct embryo transfer.
authors.affiliation: Embryology and Biotechnology of Reproduction Laboratory, Faculty of Veterinary Medicine, UFRGS, Porto Alegre, RS, Brazil. vieira_ad@yahoo.com.br
authors.forename: A D
authors.initials: AD
authors.lastname: Vieira
authors.forename: F
authors.initials: F
authors.lastname: Forell
authors.forename: C
authors.initials: C
authors.lastname: Feltrin
authors.forename: J L
authors.initials: JL
authors.lastname: Rodrigues
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects* / Q000502:physiology; D002417:Cattle / Q000196:embryology*; D015925:Cryopreservation / Q000295:instrumentation / Q000662:veterinary*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004624:Embryo Transfer / Q000662:veterinary; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D005898:Glass; D011247:Pregnancy
chemical_list: D003451:Cryoprotective Agents