Fetal limb allograft transplants in young rabbits

The behavior and growth pattern of a transplanted fetal allograft limb in young rabbits were studied. No previous similar studies have been reported in the English literature. Ninety-four fetuses of four-weeks gestation were obtained through hysterectomy. The left hind limb of the fetus was dissected and disarticulated at the hip joint, preserving the long pedicle consisting of the inferior vena cava and abdominal aorta. The skin was stripped and nails were removed from the fetal limb prior to transplantation into a subcutaneous pouch on the medial aspect of the right thigh of a six-week old rabbit. The aorta and the inferior vena cava of the fetus were anastomosed to the femoral vessels of a recipient young rabbit, using the operating microscope. The rabbits were radiographed at fortnightly intervals to assess growth in the transplanted fetal limb. The rabbits were divided into three experimental groups: Group 1 (n = 26)--vascularized fetal allograft; Group 2 (n = 6)--non-vascularized fetal allograft; Group 3 (n = 5)--vascularized fetal allograft with Cyclosporin A. Preliminary results in Group 1 showed growth in the vascularized fetal limb allograft, with a maximum accelerated growth in the first four weeks. All Group 2 non-vascularized fetal allografts showed no growth. Group 3 showed an increased and accelerated limb growth in the first six weeks of transplant. The results demonstrated that vascularized fetal allograft has the potential for low-grade immunogenicity and of growth at the initial stage, especially with adjunctive immunosuppressive therapy.