title: Comparison of cytoskeletal integrity, fertilization and developmental competence of oocytes vitrified before or after in vitro maturation in a porcine model.
abstract: Aim of the study was to investigate the effect of vitrification on viability, cytoskeletal integrity and in vitro developmental competence after in vitro fertilization (IVF) of oocytes vitrified before or after in vitro maturation (IVM) using a pig model. Oocytes from abattoir-derived porcine ovaries were vitrified at either the germinal vesicle (GV) or metaphase II (MII) stage by modified solid surface vitrification (SSV). Oocyte viability was evaluated by stereomicroscopic observation whereas their nuclear stage and morphology of microtubules and F-actin were observed by confocal microscopy after immunostaining. Fertilization was assessed by orcein staining. The survival rate after vitrification was higher for MII-stage than for GV-stage oocytes. However, the ability of surviving oocytes to reach the MII stage after vitrification at the GV stage (GV-vitrified oocytes) was similar to that of control oocytes. Furthermore, after IVM, GV-vitrified oocytes had better spindle and F-actin integrity than oocytes vitrified at the MII stage (MII-vitrified oocytes). In accordance with this result, GV-vitrified oocytes had better ability to extrude the second polar body and support male pronucleus formation after in vitro fertilization (IVF), in comparison to MII-vitrified oocytes. Fertilization rates did not differ among groups. Finally, the ability of GV-vitrified oocytes to develop into embryos was superior to that of MII-vitrified oocytes. However, both vitrified groups showed reduced blastocyst development compared with the control group. In conclusion vitrification of porcine oocytes at the GV stage is advantageous in conferring better cytoskeletal organization and competence to develop to the blastocyst stage in comparison with vitrification at the MII stage.
authors.affiliation: Research Institute for Animal Breeding and Nutrition, Herceghalom H-2053, Hungary. Electronic address: istvan.egerszegi@atk.hu.
authors.forename: István
authors.initials: I
authors.lastname: Egerszegi
authors.forename: Tamás
authors.initials: T
authors.lastname: Somfai
authors.forename: Michiko
authors.initials: M
authors.lastname: Nakai
authors.forename: Fuminori
authors.initials: F
authors.lastname: Tanihara
authors.forename: Junko
authors.initials: J
authors.lastname: Noguchi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kaneko
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagai
authors.forename: József
authors.initials: J
authors.lastname: Rátky
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kikuchi
mesh_terms: D000818:Animals; D002470:Cell Survival; D015925:Cryopreservation / Q000379:methods* / Q000662:veterinary*; D003599:Cytoskeleton / Q000648:ultrastructure*; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D008297:Male; D009865:Oocytes / Q000166:cytology*; D013552:Swine; D058989:Vitrification
keywords: Cryoprotectant; Embryo development; Immature oocyte; In vitro fertilization; Pig; Vitrification