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Brief Communications

Nature 424, 635 (7 August 2003) | doi:10.1038/424635a

Open Innovation Challenges

Pregnancy: A cloned horse born to its dam twin

Cesare Galli1, Irina Lagutina1, Gabriella Crotti1, Silvia Colleoni1, Paola Turini1, Nunzia Ponderato1, Roberto Duchi1 & Giovanna Lazzari1

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A birth announcement calls for a rethink on the immunological demands of pregnancy.

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Several animal species, including sheep, mice, cattle, goats, rabbits, cats, pigs and, more recently, mules1 have been reproduced by somatic cell cloning, with the offspring being a genetic copy of the animal donor of the nuclear material used for transfer into an enucleated oocyte. Here we use this technology to clone an adult horse and show that it is possible to establish a viable, full-term pregnancy in which the surrogate mother is also the nuclear donor. The cloned offspring is therefore genetically identical to the mare who carried it, challenging the idea that maternal immunological recognition of fetal antigens influences the well-being of the fetus and the outcome of the pregnancy.