| Abstract: | Early and late blastocysts (D7) of excellent quality were bisected by the transzonal method. The developing semiembryos without zonal protection were transferred to synchronised recipients--heifers. After bilateral transfer of the identical pair (always one semiembryo into one uterine cornu) 79.7% of the heifers were impregnated. The total gravidity was 58.8%. After ipsilateral transfer (the halves transferred individually) gravidity was confirmed in 48.2% of the cases. The survival efficiency of the halves with respect to the number of bisected embryos was 117.6% in bilateral transfer and it decreased to 93.3% after ipsilateral transfer. Identical pregnancies of twins were recorded in 36.8% of the bilateral transfers and in ipsilateral transfers only 20% of the identical pairs survived. We demonstrated the high recuperative and regenerative ability of the bovine 7 day old blastocyst by means of transzonal bisection. This was dependent on the selection of the appropriate embryo, careful manipulation aseptic technique, biologically compatible cultivation medium and rapid transfer. It is possible to attain satisfactory semiembryo survival levels in transplantation work and by means of this a significant increase of the superovulation effect. |
