A human embryo has been grown in a laboratory for twice the length of time than was previously possible in a breakthrough that could “revolutionise” medicine but also raises fresh ethical questions about when life begins.
Since scientists first fertilised an embryo in a test tube in 1969, they have never managed to keep one alive for long after the point at which the foetus implants in the womb, normally about seven days.
However researchers at Cambridge University have now grown embryos for 13 days -- a process they only stopped to avoid breaking the current legal limit of about 14 days.
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