Islet architecture and capillary bed. A: (a–d) Sequential optical slices. Insulin (green), glucagon (cyan), somatostatin (blue), and CD31 (red). (e) 3D-reconstructed view of three islets and blood vessels. (f) Side view of e. Scale bars: all 50 μm. B: Intermediate size of islet (Feret diameter = 157 μm). (a) 3D-rendered view. Clusters of β-cells (b), α-cells (c), and δ-cells (d). (e) Endocrine cells only. (f) Blood vessels only. (g) β-Cells and α-cells. (h) α-Cells and δ-cells. Scale bars: all 40 μm. C: Large islet (Feret diameter = 404 μm). (a) 3D-rendered view. (b) Blood vessels made transparent. (c and d) Enlarged views. Scale bar: 50 μm for a and b, 30 μm for c, and 20 μm for d. D: Small islets. (a, c, and e) Solid 3D-rendered views. (b, d, and f) β-Cells made transparent. Scale bars: all 15 μm. E: A cluster of small islets. (a) 3D-rendered view. (b) β-Cells and α-cells. (c) α-Cells and δ-cells. (d) Blood vessels only. (e) 3D-reconstructed view with transparent blood vessels. (f) Side view of e. Scale bar: 100 μm for a–f, 40 μm for g–i, and 20 μm for j–l.