The extraordinary moment one baby becomes two
These extraordinary pictures show the moment when identical twins are formed from a single cluster of cells.
Scientists in Japan used timelapse photography to capture the amazing images for the first time.
They recorded the development of 33 frozen embryos which had been donated for research.
Images were taken every two minutes with a digital camera attached to a microscope.
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The scientists used time-lapse photography to capture these incredible images
After thawing, 26 of the embryos developed into 'blastocysts', tiny clumps of cells no bigger than a pinhead.
Within this ball of cells a fluid-filled cavity forms, providing a 'mini-womb' in which the body of the embryo develops.
The first picture on the right shows how the expanding cluster of cells attaches to the wall of the womb in two places, before being joined by a microscopic string.
When this eventually snaps, as the second picture shows, two distinct bunches of cells are left to develop into identical twins over the next nine months.
Researchers now hope the footage will help them understand why so many IVF embryos develop into twins.
Identical twins are most likely toform when the 'blastocyst' is kept for five days or more before being transferred to the mother.
The images were released for the first time at the annual meeting of the European Society of HumanReproduction and Embryology in Lyon, France.
Researcher Dianna Payne, from the Mio Fertility Clinic in Yonago, Japan, said the pictures could help embryologists work towards avoiding twin IVF pregnancies.
"If choice of embryos is limited, the mother could be prepared for the likelihood of twins and given appropriate clinical advice.'
"If you see two inner cell masses, then I think you can be fairly sure that this is an embryo at risk of producing twins," she said.
"Then, either a decision could be made about whether to transfer those embryos, or, if the choice of embryos is limited, the mother could be prepared for the likelihood of twins and given appropriate clinical advice."
The risk of having IVF twins could potentially be removed completely, she said. twins could potentially be removed
