Five oocytes divided to the two-cell stage, and of these, three continued to divide to the six- to ten-cell stage. One embryo continued to develop to the compacted stage, when the individual cells started to flatten and increase their contact with one another.
Mr Heindryckx said: "To our knowledge, this is the first report describing the development of cloned human embryos using in vitro matured oocytes and non-autologous transfer via a conventional method of nuclear transfer.
"Our final goal is to use human therapeutic cloning for infertility treatment by creating artificial eggs and sperm for patients who are infertile because of absence or premature loss of eggs or sperm. We would do this by isolating embryonic stem cell lines from cloned early embryos and driving these embryonic stem cells to develop into eggs and sperm in the laboratory."
However, Mr Heindryckx warned that there was a long way to go and many problems to overcome before he and his colleagues could reach their goal.
"None of these early embryos developed to the blastocyst stage, and failure to do so could reveal some problems in gene activation, especially in cloned embryos. So, first we have to understand how to get cloned blastocysts of good quality from in vitro matured oocytes. This will be difficult because it is well known that embryonic development is compromised when in vitro matured oocytes are used, and
Source:European Society for Human Reproduction and Embryology