title: Pregnancies from vitrified equine oocytes collected from super-stimulated and non-stimulated mares.
abstract: The objectives were to compare embryo development rates after transfer into inseminated recipients, vitrified thawed oocytes collected from super-stimulated versus non-stimulated mares. In vivo matured oocytes were collected by transvaginal, ultrasound guided follicular aspiration from super-stimulated and non-stimulated mares 24-26 h after administration of hCG. Oocytes were cultured for 2-4 h prior to vitrification. Cryoprotectants were loaded in three steps before oocytes were placed onto a 0.5-0.7 mm diameter nylon cryoloop and plunged directly into liquid nitrogen. Oocytes were thawed and the cryoprotectant was removed in three steps. After thawing, oocytes were cultured 10-12 h before transfer into inseminated recipients. Non-vitrified oocytes, cultured 14-16 h before transfer, were used as controls. More oocytes were collected from 23 non-stimulated mares (20 of 29 follicles), than 10 super-stimulated mares (18 of 88 follicles; P < 0.001). Of the 20 oocytes collected from non-stimulated mares, 12 were vitrified and 8 were transferred as controls. After thawing, 10 of the 12 oocytes were morphologically intact and transferred into recipients resulting in one embryonic vesicle on Day 16 (1 of 12 = 8%). Fourteen oocytes from super-stimulated mares were vitrified, and 4 were transferred as controls. After thawing, 9 of the 14 oocytes were morphologically intact and transferred into recipients resulting in two embryonic vesicles on Day 16 (2 of 14 = 14%). In control transfers, 7 of 8 oocytes from non-stimulated mares and 3 of 4 oocytes from super-stimulated mares resulted in embryonic vesicles on Day 16. The two pregnancies from vitrified oocytes resulted in healthy foals.
authors.affiliation: Department of Physiology, Colorado State University, Fort Collins 80523-1683, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Maclellan
authors.forename: E M
authors.initials: EM
authors.lastname: Carnevale
authors.forename: M A
authors.initials: MA
authors.lastname: Coutinho da Silva
authors.forename: C F
authors.initials: CF
authors.lastname: Scoggin
authors.forename: J E
authors.initials: JE
authors.lastname: Bruemmer
authors.forename: E L
authors.initials: EL
authors.lastname: Squires
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D015925:Cryopreservation; D005314:Embryonic and Fetal Development; D005260:Female; D006736:Horses; D007315:Insemination, Artificial / Q000662:veterinary; D009865:Oocytes / Q000502:physiology / Q000637:transplantation; D011247:Pregnancy; D013480:Superovulation; D020858:Tissue and Organ Harvesting / Q000662:veterinary