Morphology of experimental, organ-specific insulitis of the mouse pancreas.

The morphologic and metabolic effect of a single intracutaneous injection of homologous endocrine pancreas in Freund's complete adjuvant (CFA) was studied in 100 mice and compared with control groups which had been (1) immunized with murine insulin in CFA, (2) injected with CFA alone, or had (3) received no treatment. There were no differences between the control groups as regards the morphology of the pancreatic islets, and the glucose tolerance was normal. Mice immunized with islet homogenate exhibited morphological changes in the form of degranulation and cytoplasmic disintegration. These changes involved B-cells as well as A2-cells and were present from 7 to 18 days after the immunization. A significant reduction in glucose tolerance was observed 14 days after the immunization. Another characteristic finding in the islets from the immunized mice was the extra-vascular presence of mononuclear, agranular cells which on the basis of their morphological criteria appeared to represent lymphocytes.