Tissue rejection
From Tardis Wiki, the free Doctor Who reference
Tissue rejection was a medical term that referred to the incompatibility of differing body tissue when transplanted. Mehendri Solon managed to overcome this problem, a talent he later used when restoring Morbius. (DW: The Brain of Morbius)
Cyber-conversion only worked on Mondasians and humans as the genome of other species made the process falter, resulting in tissue rejection. (DWM: The Flood)
