Islet fibrosis and infiltration of immune cells in the islets of aged group of mice (left panels, WTs; right panels, TGs). Representative cases are shown in each genetic group (in TGs, the islets harboring intra-islet ducts are shown). Bar, 50 μm. (a) Picro-Sirius red staining of the islets. The fibrosis, shown in the red fibrotic structures, is discernible inside the islet of TG. The lumen in the intra-islet duct is also stained with Picro-Sirius red. In the WT case, almost no such structures were observed inside the islet. (b) Immunostaining of islets for F4/80 with alcian blue staining. Representative images are shown in each genetic group. No F4/80-positive cells are observed in the islet of WT. In contrast, several F4/80-positive cells (brown) are discernible near or inside the islets in TG (yellow triangles). The inner side of the component of lumen in the intra-islet duct is stained nonspecifically. (c) Immunostaining of islets for CD3 with alcian blue staining. CD3-positive cells (brown) are recruited to the islets of TG. No CD3-positive cells are observed in the islets of WTs.