First human-animal embryos created

Britain's first human-animal hybrid embryos have been created, forming a crucial first step, scientists believe, towards a supply of stem cells that could be used to investigate debilitating and so far incurable conditions such as Alzheimer's, Parkinson's and motor neurone disease.

Lyle Armstrong, who led the work, gained permission in January from the Human Fertilization and Embryology Authority (HFEA) to create the embryos, known as "cytoplasmic hybrids".

His team at Newcastle University produced the embryos by inserting human DNA from a skin cell into a hollowed-out cow egg. An electric shock then induced the hybrid embryo to grow. The embryo, 99.9 percent human and 0.1 percent animal, grew for three days, until it had 32 cells.