Abstract
To enable us to handle a large number of oocytes at a given time and to have an increased throughput of cloned embryos, we attempted the Handmade cloning (HMCTM) technique, a zona-free method of bovine somatic cell nuclear transfer. Our objective was to study the developmental competence of the HMCTM derived embryos obtained using different types of somatic cells. A total of 6,874 cumulus-oocyte-complexes were used with either 7th or 11th passage fibroblasts (1st and 2nd groups, respectively), which were prepared from male animals, or granulosa cells (3rd group) as nuclei donors. The average cleavage rate was 65%, accompanied by a blastocyst rate of just 2% for the cleaved products and 5% for the > 8-cell embryos, and there was no significant difference between the three groups. Out of 27 blastocysts recovered, 22 blastocysts were transferred to 22 recipients, resulting in two pregnancies. One pregnancy was lost after the fourth week while the other progressed to full term with the birth of a male calf. This first successful cloning of a male calf with the HMCTM technique in Europe indicates the successful adoption and establishment of this technique in our laboratory, and that this technique can be successful in producing viable embryos.
