[Wound healing of liver and kidney after repeated thermocoagulation (author's transl)]

Two focal thermolesions were made on rats liver and kidney at an interval of 4 weeks, and comparative histological and cell kinetic studies were performed on the wound healing process after a single and repeated thermolesion(s). The wound healing after the thermolesion took place very gradually. An active granulation tissue was found till the 4th--5th week after the thermolesion. The resorption of the necrotic carbonized material was particularly difficult. Only after 6--8 weeks did the fibrous scarring start. The histological analysis of the granulation tissue and of the scar tissue showed no significant difference in cell components and cell density after the single and after the double thermolesion(s). Autoradiographically, however, it was shown that the proliferation maximum of fibroblasts in the granulation tissue and of mesenchymal cells in the surrounding uninjured tissues after the double thermolesions occurred 24 h later than after the single thermolesion. Furthermore, the labelling index of the fibroblasts in the granulation tissue was lower after double lesions than after the single lesion. Once the scar tissue was formed, there was no significant difference between the labelling indices of mesenchymal cells after single and double lesions. By the present study it was suggested that delayed wound healing after thermolesions may be caused by decreased proliferation activity of mesenchymal cells, combined with delayed resorption of carbonized material. An implication of altered T cell system in the delayed wound healing was also discussed.