[Pathological changes in allogenic skin in combined radiation-burn injury in rats]

Skin allografts were transplanted to rats inflicted with third degree burns of 15% of BSA alone or combined with 5 Gy gamma ray radiation. Histopathological, histochemical and ultrastructural changes of the allografts were examined at different postoperative periods. In burned rats, allografts began to be rejected on the 8th postoperative day, showing degeneration and necrosis of its epithelial cells. Only in one rat it survived on the 14th day (10%), and all allografts were rejected before the 19th day. In contrast to this, most allografts (60-80%) on the rats with combined injury survived well for a period of 29 days. Epithelial cells and collagen fibers of the allografts degenerated in 1 to 4 days postoperation, and recovered to near normal during 9 to 14 days. During 24 to 29 days postoperation, the epithelial cells and appendices appeared almost normal in texture except an infiltration of a few lymphocytes and monocytes. The restoration of degenerated collagen, however, was slower than that of degenerated epithelium. The result shows that the survival time of skin allografts in severe combined radiation burn injury is prolonged than that in burns.