| Abstract: | Single blastomeres from eight-cell stage bovine embryos matured and fertilized in vitro were electrically fused with enucleated oocytes matured in vitro. In experiment 1, The percentage of these reconstituted embryos developed to the two- to eight-cell stage 48 hr after electrofusion was increased when both the eight-cell embryos and the enucleated oocytes were derived from oocytes cultured with granulosa cells (14% vs. 38%). In experiment 2, the relationship between activation of oocytes and developmental ability of reconstituted embryos was examined. Although both ethanol and electrical stimulation efficiently induced parthenogenetic activation of oocytes matured in vitro for 26–28 hr (ethanol, 89%; electrical stimulation, 73%), the ratio of the second polarbody extrusion differed (80% vs. 22%). Ethanol-treated enucleated oocytes, however, were not significantly different from the early cleavage of the reconstituted embryos 48 hr after electrofusion (nontreated, 38%; treated, 43%). In experiment 3, reconstituted embryos at the two- to eight-cell stage 48 hr after the electrofusion were cocultured with granulosa cells for 6–7 days. Of 69 embryos, one developed to a morula and three developed to blastocysts. © 1993 Wiley-Liss, Inc. |
