Profound leakiness of postcapillary islet venules is unrelated to endothelial apoptosis.
(A and B) Isosurfacing rendition of vascular staining from region depicted in Figure 2, H and I, before and 10 minutes after injection of the dye, respectively. w/h = 1.52/d = 5/z = 26. (C and D) Naive control animal imaged before and 14 minutes after injection with dextran–Texas Red (dextran-TxRed). w/h = 1.52/d = 5/z = 33. (E) Quantitative analysis of vascular leakiness as observed in A and B compared with baseline in C and D. Leakiness was defined as increase in isosurfaced dextran–Texas Red–derived fluorescent signal and was normalized to T = 0 immediately after injection. Representative of observations from 3 individual prediabetic animals and 3 controls. (F and G) TUNEL staining was performed to reveal ongoing apoptosis in the transfer model during the late prediabetic phase. TUNEL+ nuclei are exclusively observed within the β cell mass and inflammatory infiltrate. Red arrows indicate vascular structures and the lack of ongoing apoptosis within these regions. Images are representative of at least 3 consecutive sections from 4 individual prediabetic animals. Scale bars: 100 μm.