The histopathologic changes occurring in 23 allografted canine pancreases were studied. No immunologic suppression was utilized.
Early hemorrhagic necrosis occurred as a consequence of major venous thrombosis of the graft. In the absence of this complication, progressive pathologic changes consisting of edema, vascular dilatation, mononuclear cell infiltration, fibroblastic proliferation, and small vessel thrombosis and necrosis were found from 1 to 13 days after transplantation.
The sequence of these changes suggests that fat necrosis in the grafted pancreas is secondary to rejection or to early thrombosis of the main vessels rather than to pancreatitis.
No clear changes were observed that favored a different rejection mechanism or timing of the immune response for exocrine or endocrine tissues.