“More than twenty years after the first attempts to create human clones in a petri dish, US researcher Shoukrat Mitalipov and his team at Oregon Health & Science University have for the first time successfully created fertilizable egg cells from skin cells.
The 270 manipulated egg cells had been donated by IVF patients for research purposes.
The nucleus of the egg cells was removed using the cloning technique developed for the cloned sheep "Dolly" and replaced with the genetic material, the chromosomes, from foreign skin cells.
Then, as reported in "Nature Communications," the number of chromosomes was halved in a process synchronized with the cell division cycle of egg cells. This paved the way for fertilization with sperm, which contain the second set of parental chromosomes. However, the halving of the chromosomes in the egg, referred to as "mitomeiosis," was far from perfect. Less than one in ten fertilized cloned egg cells divided before the experiment was terminated. Many of the early embryos had chromosomal abnormalities. Furthermore, the genetic material from the skin cells was not yet epigenetically ready for fertilization. The researchers write that "extensive further research is needed" before routine application in artificial insemination.” [1]
Fertilized egg is not a clone of any human how young parents discover early on with their babies. Was Dolly produced without fertilization, real identical clone of another sheep?
Yes, Dolly the sheep was a clone of another sheep, produced without fertilization, using a process called somatic cell nuclear transfer (SCNT). The nucleus from a single adult sheep cell was transplanted into an unfertilized egg cell from a different sheep that had its own nucleus removed. The resulting embryo was then implanted into a surrogate mother, meaning Dolly's nuclear DNA came entirely from one adult sheep, but her mitochondrial DNA came from the egg donor.
How the process worked
Donor cell: Scientists took a nucleus from a mammary gland cell of a Finn Dorset sheep.
Egg cell donor: They took an unfertilized egg cell from a Scottish Blackface sheep and removed its nucleus (the genetic material).
Fusion: The nucleus from the Finn Dorset cell was inserted into the Scottish Blackface egg cell, and the two cells were stimulated with an electric pulse to fuse and start dividing.
Development: The resulting embryo was grown in a lab and then implanted into a surrogate mother, a Scottish Blackface sheep.
Birth: Dolly was born, a genetically identical copy of the Finn Dorset sheep that donated the original nucleus.
1. Geklonte Eizellen des Menschen. Frankfurter Allgemeine Zeitung; Frankfurt. 01 Oct 2025: N1.
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