title: Effects of cumulus cells on male pronuclear formation and subsequent early development of bovine oocytes in vitro.
abstract: Bovine oocytes were matured in culture with and without cumulus cells. The proportion of oocytes matured to metaphase-II 24 h after culture was not different between those matured with and without cumulus cells. When cultured oocytes were inseminated in vitro, high proportions (84 to 87%) of oocytes were penetrated, with no difference between those matured with and without cumulus cells. However, the proportion of oocytes penetrated at the male pronuclear stage was significantly higher in cumulus-intact than in cumulus-free oocytes (90 vs 31%). The proportion of oocytes cleaved beyond the 8 approximately 32-cell stage was also significantly higher in cumulus-intact than in cumulus-free oocytes. It is concluded that the cumulus cells may have an important function for normal cytoplasmic maturation of bovine oocytes in vitro.
authors.affiliation: Département des Sciences Animales, Université Laval Québec, Canada G1K 7P4.
authors.forename: R C
authors.initials: RC
authors.lastname: Chian
authors.forename: K
authors.initials: K
authors.lastname: Niwa
authors.forename: M A
authors.initials: MA
authors.lastname: Sirard