The surgical transplantation of a tissue from one member of a heterogeneous population to another member of the same species is known as an allograft or homograft; the same procedure performed across species lines is termed a xenograft or heterograft. Despite the technical feasibility of both such procedures, the more or less rapid destruction of the transplant is the ultimate outcome in the vast majority of attempts.
One apparent exception to this rule is transplantation of the cornea. In carefully selected cases, a high proportion of successful, transparent grafts are now being achieved. These clinical successes provide a striking contrast to the failures that generally accompany the transplantation of most other tissues.
Despite our present level of accomplishment in keratoplasty, the procedure has not attained a position of routine success. A significant number of even the most carefully selected cases end in failure in the hands of accomplished surgeons. More
LEIBOWITZ HM, ELLIOTT JH. Chemotherapeutic Immunosuppression of the Corneal Graft ReactionI. Systemic Antimetabolites. Arch Ophthalmol. 1966;75(6):826-835. doi:10.1001/archopht.1966.00970050828023