HOMOLOGOUS TRANSPLANTATION OF TISSUES

CONTINUED growth and permanent survival of tissues transplanted from one human being to another have been unmistakenly demonstrated only when the transfer has been made between identical twins. Relatively acellular, inert tissues, such as bone and cartilage, have been used satisfactorily as homografts, but they serve only as a bridge or supporting structure for the invading tissues of the host. The cells of the graft die and are replaced by invading cells of the recipient. Although satisfactory clinical results are obtained, such grafts cannot be considered to have survived permanently. Homografts of corneal tissue have given satisfactory, permanent results in many cases. The cornea also is a relatively acellular tissue. Maumenee and Kornblueth¹have demonstrated that the majority of the stromal cells continue to live in the graft and do not show a massive degeneration or replacement at any time after transplantation. They are supplemented, at least to a