MORPHOLOGICAL OBSERVATIONS ON PANCREATIC-ISLET BLOOD-VESSELS IN LOW-DOSE STREPTOZOCIN-TREATED MICE

The aim of this study was to observe modifications occurring within th e blood vessels of pancreatic islets in low-dose streptozocin (STZ)-tr eated mice. Forty-two male C57 BL/6J mice were given 40 mg STZ on 5 co nsecutive days and killed 6 or 10 d after the first STZ injection. Imm unocytochemistry revealed a dense accumulation of cells carrying the 7 D10 epitope, related to macrophage inhibitor factor, arranged around t he 'vascular pole' of the islets on d 6, and a small number of positiv e cells within the islets on d 10. Many Ia positive cells (equivalent to MHC class II antigen positive elements) were also found at the peri phery of the islet. Ultrastructural observations showed the presence o f monocytes within almost all the capillary vessels encircling the isl ets and entering them at the 'vascular pole' (d 6). On d 10 capillary lumina no longer contained marginating monocytes but activated macroph ages were seen in the islet parenchyma.