Scientists in Japan have cloned a mouse from a single drop of blood.
Circulating blood cells collected from the tail of a donor mouse were used to produce the clone, a team at the Riken BioResource Center reports in the journal Biology of Reproduction.
The female mouse lived a normal lifespan and could give birth to young, say the researchers.
Scientists at a linked institute recently created nearly 600 exact genetic copies of one mouse.
Mice have been cloned from several different sources of donor cells, including white blood cells found in the lymph nodes, bone marrow and liver.
The Japanese research group investigated whether circulating blood cells could also be used for cloning.
Their aim was to find an easily available source of donor cells to clone scientifically valuable strains of laboratory mice.
The team, led by Atsuo Ogura, of Riken BioResource Center in Tsukuba, took blood from the tail of a donor mouse, isolated the white blood cells, and used the nuclei for cloning experiments, using the same technique that produced Dolly the sheep in Edinburgh.
The process, known as somatic cell nuclear transfer, involves transferring the nucleus from an adult body cell - such as a blood or skin cell - into an unfertilised egg that has had its nucleus removed.
Reporting their findings in the US journal, Biology of Reproduction, the scientists said the study "demonstrated for the first time that mice could be cloned using the nuclei of peripheral blood cells".