[Light microscopical, electron microscopical and clinical findings in orthotopic allogenic porcine liver homografts (author's transl)].

Orthotopic allogenic liver transplantations were carried out on 39 pigs. The length of survival time ranged from a few hours until 179 days. The clinical and biochemical laboratory findings as well as the macroscopical, light microscopical and electron microscopical findings established by biopsy and autopsy in the period after the transplantation are described and discussed with regard to their diagnostic significance and pathogenesis. The causes of death are generalized haemorrhages (15 cases), post-operatively bleeding gastric ulcers (12 cases), infections (7 cases), and early or late complications connected with the surgical interventions (5 cases). Observations of liver homografts over a long period after healing-in without complications and during sufficient function of the transplant show (without immunosuppressive treatment) the development of alterations in accordance with the features of chronic aggressive hepatitis and subsequent liver cirrhosis. Complications resulting from this account for some of the established causes of death. According to the results of experiments in animals surviving for a longer time after transplantation there are a general adaptive activation of metabolism and focal alterations in the outer cell membrane of the parenchymal cells in the transplanted liver. This alteration in the cell membrane of the liver epithelial cells causes an abnormal permeability and may lead to partial peripheral lysis and to total lytic necrosis (colliquation necrosis) of these cells. The main cause of these changes is ischaemia or hypoxia brought about by a variety of factors and the cytolytic effect of specifically sensitized lymphocytes ("killer", lymphocytes, immunocytes, effector cells) of the host organism which is the basis of the actual immunologic rejection process. The observed increase of glutamic oxalacetic transaminase (GOT) and lactate dehydrogenase (LDH) as well as potassium in the blood serum may be regarded as a sign of a progressive (developing) rejection or a chronic insufficience of blood circulation of the transplant. Long-term observations show the tendency for a slow continuous reduction in number of the erythrocytes and leucocytes in the host animals. The behaviour of the macrophages (Kupffer cells) in the liver transplant in relation to erythrocytes, thrombocytes and also lymphocytes of the host organism requires particular attention.