Inflammatory infiltrate of mononuclear cells in an islet from a 2-year-old patient with type 1 diabetes of short duration. Mononuclear cells in and around islets are shown by yellow arrows. This patient was reported by Willy Gepts in his original contribution on insulitis in 1965 (45). The photomicrograph comes from the collection of W. Gepts and was kindly provided by Danny Pipeleers.