title: Bovine oocyte vitrification before or after meiotic arrest: effects on ultrastructure and developmental ability.
abstract: The nuclear stage at which oocytes are cryopreserved influences further development ability and cryopreservation affects ultrastructure of both cumulus cells and the oocyte. In this work, we analyze the effects of vitrification at different nuclear and cytoplasmic maturation stages on the oocyte ultrastructure and developmental ability. Culture in TCM199 + PVA with roscovitine 25 M during 24h led to meiotic arrest (MA) in cumulus-oocyte complexes (COCs), while permissive in vitro maturation (IVM) was performed in TCM199, 10% FCS, FSH-LH and 17beta-estradiol for 24 h. Oocytes were vitrified using the open pulled straw method (OPS) with minor modifications. Fresh and vitrified/warmed COCs were fixed as immature, after IVM, after meiotic arrest (MA) and after MA + IVM. Vitrification combined with MA followed by IVM produced the highest rates of degeneration, regardless of the vitrification time. As a consequence, lower proportions of embryos cleaved in these groups, although differences were eliminated at the five-eight cell stage. Development rates up to day 8 were similar in all experimental groups, being significantly lower than those in fresh controls. Only oocytes vitrified after IVM were able to give blastociysts. The morphological alterations observed can be responsible for compromised development. More research is needed to explain the low survival rates of the bovine oocyte after vitrification and warming.
authors.affiliation: Servicio Regional de Investigación y Desarrollo Agroalimentario, Camino de los Claveles 604, Somio, 33203 Gijón, Asturias, Spain. mcdiez@serida.org
authors.forename: Carmen
authors.initials: C
authors.lastname: Diez
authors.forename: Paloma
authors.initials: P
authors.lastname: Duque
authors.forename: Enrique
authors.initials: E
authors.lastname: Gómez
authors.forename: Carlos O
authors.initials: CO
authors.lastname: Hidalgo
authors.forename: Carolina
authors.initials: C
authors.lastname: Tamargo
authors.forename: Aida
authors.initials: A
authors.lastname: Rodríguez
authors.forename: Lina
authors.initials: L
authors.lastname: Fernández
authors.forename: Santiago
authors.initials: S
authors.lastname: de la Varga
authors.forename: Alba
authors.initials: A
authors.lastname: Fernández
authors.forename: Nieves
authors.initials: N
authors.lastname: Facal
authors.forename: Maite
authors.initials: M
authors.lastname: Carbajo
mesh_terms: D000818:Animals; D002417:Cattle; D002467:Cell Nucleus / Q000502:physiology / Q000648:ultrastructure; D002478:Cells, Cultured; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D003470:Culture Media; D003593:Cytoplasm / Q000502:physiology / Q000648:ultrastructure; D046149:Embryo Culture Techniques / Q000662:veterinary; D004958:Estradiol / Q000008:administration & dosage; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage; D007986:Luteinizing Hormone / Q000008:administration & dosage; D008540:Meiosis; D008854:Microscopy, Electron; D009865:Oocytes / Q000502:physiology* / Q000648:ultrastructure*; D006080:Ovarian Follicle / Q000166:cytology
chemical_list: D003470:Culture Media; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone