We studied the capacity of rabbit oocytes for electrofusion with morula blastomeres and fetal fibroblasts. The morula blastomeres fused with aging ooplasts more readily than the fetal fibroblasts: 92.9 versus 63.0%, p < 0.001. The fetal fibroblasts fused with young enucleated oocytes more efficiently than with the aging ones: 98.4 versus 63.0%, p < 0.001. Serum starvation of the fetal fibroblasts in DMEM medium for 7-14 days reduced their capacity for fusion with young ooplasts, as compared to that after starvation for 0-4 days: 67.2 versus 98.9%, p < 0.01). The increased time of "starvation" in an "impoverished" medium reduced the capacity of fetal fibroblasts with aging ooplasts as compared to the fibroblasts cultivated in the full medium and in the "impoverished" medium for one or two days: 64.5 versus 37.4%, p < 0.01. Hence, the efficiency of the fusion of the oocytes with nuclear donor cells depends on the age of the recipient oocyte, the origin of nuclear donor cells, and the conditions of cultivation.
Animals Blastomeres