title: In vitro and in vivo development of bovine embryos from zygotes and 2-cell embryos microinjected with exogenous DNA.
abstract: The objectives of these experiments were: 1) to determine an effective culture method for production of transferable bovine embryos following exogenous DNA microinjection; 2) to determine the effect of these methods on the ability of the injected zygotes and 2-cell embryos to develop in vivo; and, 3) to compare development of embryos microinjected as zygotes or 2-cell embryos. DNA fragments encoding bovine growth hormone (bGH), bGH-10Delta6, and a bGH antagonist, bGH-M8 (5) were used. A total of 639 zygotes and 153 2-cell embryos were injected. Zygotes and 2-cell embryos microinjected with bGH-M8 were incubated for 6 days in oviducts of intermediate recipients (rabbits or sheep) or co-cultured in vitro with bovine oviduct epithelial cells. Zygotes and 2-cell embryos microinjected with bGH-10Delta6 were co-cultured in vitro only. The most effective method for the production of transferable bovine embryos following exogenous DNA microinjection was via in vitro co-culturing with bovine epithelial cells. For example, 32.3% of the bGH-M8 and 33.5% of the bGH-10Delta6 microinjected zygotes reached the morula/blastocyst stage while 48.4% and 63.0% of the 2-cell embryos injected with bGH-M8 and bGH-10Delta6, respectively, developed to the morula/blastocyst stage. The percentage of blastocysts obtained for control, non-injected zygotes and 2-cell embryos was 34.5% and 69.6%, respectively. The developmental rate to the morula/blastocyst stage was approximately 20% greater for embryos obtained from microinjected 2-cell embryos relative to microinjected zygotes. However, there was no significant difference in pregnancy rates following transfer of these blastocysts to cow uteri.
authors.affiliation: National Institute of Animal Husbandry Department of Animal Reproduction Balice/Krakow, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Jura
authors.forename: J J
authors.initials: JJ
authors.lastname: Kopchick
authors.forename: W Y
authors.initials: WY
authors.lastname: Chen
authors.forename: T E
authors.initials: TE
authors.lastname: Wagner
authors.forename: J A
authors.initials: JA
authors.lastname: Modlinski
authors.forename: M A
authors.initials: MA
authors.lastname: Reed
authors.forename: J R
authors.initials: JR
authors.lastname: Knapp
authors.forename: Z
authors.initials: Z
authors.lastname: Smorag