Enteroendocrine cell. Colured transmission electron micrograph (TEM) of a section through an enteroendocrine cell within the small intestine. Endocrine cells secrete hormones that act locally or on distant target organs via the bloodstream. They store their secretory products in cytoplasmic granules (brown) that are discharged into the surrounding tissue or blood vessels. Enteroendocrine cells, also known as argentaffin or enterochromaffin cells, are specialized endocrine cells of the gastrointestinal tract. They produce hormones such as serotonin, somatostatin, motilin, cholecystokinin, gastric inhibitory peptide, neurotensin, vasoactive intestinal peptide, and enteroglucagon. Magnification: x6, 000 when printed 10 centimetres