Scientists in northeast China injected fluorescent green protein into three sows’ embryos when they were bred in December 2006.
The pigs glow green when placed under an ultraviolet light.
Liu Zhonghua, a professor at Northeast Agricultural University in the city of Harbin, was quoted as saying that "the mouths, trotters and tongues of the two piglets glow green under ultraviolet light, which indicates the technology to breed transgenic pigs via cell nuclear transfer is mature".
"This technology promises to breed excellent transgenic pigs and even raise special pigs to provide organs for human transplant operations in the future," he said.
