title: Early morphological events of in vitro fertilized bovine oocytes with frozen-thawed spermatozoa.
abstract: Bovine follicular oocytes were matured and inseminated in vitro with spermatozoa capacitated in vitro. The first evidence of sperm penetration was observed at 3 h after insemination. The penetration rate increased until 5 h, and reached a maximum rate (92%) at 5 h. Decondensation of the sperm head and pronuclear formation were observed 4 h and 7 h after insemination, respectively. Female chromatins of all penetrated oocytes were activated at 3 h, and female pronuclei were formed at 7 h after insemination. Percentages of oocytes with male and female pronuclei at 9 h were 88 and 94%. Polyspermy (4, 7, 19 and 29% at 4, 5, 7 and 9 h after insemination, respectively) and abnormal development of male pronuclei (6 and 7% at 7 and 9 h after insemination, respectively) were also seen.
authors.affiliation: Department of Animal Science, College of Agriculture, Kyoto University, Kyoto, 606 Japan.
authors.forename: K
authors.initials: K
authors.lastname: Saeki
authors.forename: H
authors.initials: H
authors.lastname: Kato
authors.forename: Y
authors.initials: Y
authors.lastname: Hosoi
authors.forename: M
authors.initials: M
authors.lastname: Miyake
authors.forename: K
authors.initials: K
authors.lastname: Utsumi
authors.forename: A
authors.initials: A
authors.lastname: Iritani