The dissection showed that Weiwei had an oversized heart and liver and five lobes in its right lung, but its intestinal tract and genital system were normal, said Professor Ma Shiyuan, a member of the embryo transplantation project, who dissected the calf Saturday.

　　However, Ma and his colleagues have not yet been able to identify the exact reason for Weiwei's death. "Further cell analysis and research are necessary," said Chen Dayuan, a researcher with the Animal Research Institute of the Chinese Academy of Sciences.

　　Chen himself, though, is also inclined to believe that structural problems caused Weiwei's death.

　　Weiwei, a female calf, was born through a Cesarean section at 9:25 pm last Friday at the Jinan-based Shandong Zhongda Animal Embryo Engineering Center, but died a little over one hour after her birth.

　　The birth of Weiwei marked the first successful experiment of its kind wholly conducted in China.

　　Under the same research program, a dozen other pregnant cows are expected to give birth to cloned calves in the days to come.