Fig. 4. Characterisation of cells. (A,A') C-peptide (red) and insulin (green). Bar, 20 µm. (B) TEM showing cells with -cell-like secretory granules (arrowheads). Bar, 2 µm. (C) Immuno-EM showing a positive signal for insulin in the lower right cell. The upper right cell has secretory granules that are not insulin-positive. Bar, 0.5 µm.