Fig. 1

Sections of 7-day-old female C57BL/6 (A) and NOD (B–D) mouse pancreata stained for immunoreactive glucagon (blue) and insulin (brown) (magnification A–C: 320× and D: 500×). Small glucagon-positive islets (arrows) are present throughout the tissue of NOD (B–D) but not C57BL/6 mice (A). Many insulin-containing islets in NOD mice have unusually large proportions of glucagon-positive α cells at their periphery (D), as compared to age-matched C57BL/6 (A).