title: In vitro fertilization and cleavage of in vivo matured bovine oocytes.
abstract: The effect of the interval between onset of estrus and oocyte collection on in vitro fertilization (IVF) rates has been investigated. The oocytes were surgically collected 6-18 h (Group I), 19-24 h (Group II), 25-29 h (Group III) and 30-36 h (Group IV) after the beginning of estrus. Recognizable stages of nuclear maturation were identified in 54.9% of the oocytes used for IVF (5.9% at germinal vesicle, 31.4% at metaphase I, 17.6% at metaphase II); the other 45.1% were degenerate. Considerable between- and within-cow variation in oocyte morphology, oocyte maturation and IVF results was observed. The overall fertilization and cleavage rates (to four-cell stages) were 26.5 and 6.0%, respectively. The fertilization rate increased as the interval between onset of estrus and collection increased and was optimal 30-36 h after onset. Thus, onset of estrus proved an effective means of timing oocyte collection for IVF.
authors.affiliation: Centre de Recherche en Reproduction Animale, Faculté de Médecine Vétérinaire, Université de Montréal, C.P. 5000, St-Hyacinthe, Québec, J2S 7C6, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Greve
authors.forename: D
authors.initials: D
authors.lastname: Bousquet
authors.forename: W A
authors.initials: WA
authors.lastname: King
authors.forename: K J
authors.initials: KJ
authors.lastname: Betteridge