Xen- (prefix): Referring to something foreign or different. For instance: Xenoantigen - An antigen present in multiple species. Xenograft - A surgical procedure involving tissue transplanted from one species to another, dissimilar species, genus, or family. Xenotransplantation - The process of transplanting organs or tissues from one species to another, such as the heart transplant from a baboon to Baby Fae in 1984 at Loma Linda University in California. Xenotropic virus - A virus capable of replicating in the cells of a species different from its usual host. The prefix "xen-" originates from Late Latin and Greek, derived from "xenos," which means stranger, guest, or host. Both xen- and xeno- are variations of the same prefix.
