Until about World War I, the main strategy for making allotransplantation viable focused on surgical technique. As Payr put it in 1906, “The circumstances that have to concur favorably are so numerous in their nature and in part probably still unknown that everyone has to be content with a certain percentage of successful cases. However, I maintain that with enhanced technique the results will improve.” Surgeons therefore emphasized the necessity for perfect surgical conditions, such as asepsis. They also tried to find the best implantation sites for their transplants; to provide better conditions for blood supply, either by opening up the transplant, by leaving a vascular stem, or by creating a vascular linkup; and, finally, to develop methods for shortening the interval between organ removal and transplantation as well as for preserving the transplant.

Implantation Sites

Surgeons generally attached great importance to the place into which they transplanted organs or tissues. One option was to transplant the organ into its natural site—in other words, orthotopically. To make sure that a transplanted ovary or testicle would secrete germ cells, for example, surgeons tried to reconstruct the anatomical conditions of the organ’s natural site. A further argument in favor of orthotopic transplantation was that trophic factors fostering organ growth were assumed to exist in certain places in the body. In connection with testicle transplantation, Voronoff argued in 1925 that the body’s humoral composition varied from place to place. Each organ had evolved in its special site over millennia. Only its original location provided the optimal physiological conditions and only there would the bloodstream supply it with the substances most suitable for its growth. Along similar lines, some surgeons tried to provide a semblance of an organ’s original environment by transplanting pieces of the organ into tissues of the same kind, such as gland into gland.

Orthotopic transplantation was comparatively rare; heterotopic implantations were much more common. Most doctors thought that the function of many organs, such as glands, did not depend on their exact location within the body, and there was practically no place in the body (at least in animals) that was not tried for the implantation of some kind of tissue.