Composite light micrograph of a pancreatic islet with different fluorescent stains to show the relative content and distribution of the cells that secrete the major peptide hormones of the islet: insulin (beta or B cells, colored blue), glucagon (alpha or A cells, colored green), and somatostatin (delta or D cells, colored red). One will note that there are a few fluorescent cells, outside the islet, that stain one of the three colors. These are either isolated islet cells that 1) are not confined to the islet, 2) belong to an islet almost entirely outside the plane of the section, or 3) are an artifact of sectioning, which was done on frozen tissue. Magnification: 400X.