Histologic examination of the homografted heart at the time of "rejection" shows round cell infiltration, interstitial hemorrhage, edema, and necrosis.1-3 With the obvious histocompatibility of cardiac autografts one would not anticipate these specific alterations in histologic appearance. However, with electron microscopy we have demonstrated certain changes in intercellular structure after excision and reimplantation of the heart.4 Neural elements are principally involved. Therefore, we have examined the morphology of normal canine hearts and hearts subjected to sham operation, autotransplantation, and homotransplantation. Using silver impregnation and trichrome counter stain we have attempted to evaluate the effect of these operations on neural and collagenous elements in the heart.
Studies were carried out on four groups of mongrel dogs: (1) three normal controls; (2) two animals subjected to sham operation, including thoracotomy, extracorporeal circulation, hypothermia, and cardiac arrest; (3) five orthotopic cardiac autotransplants; (4) two dogs subjected to cardiac homotransplantation.Autotransplantation