The enteroendocrine “letter cells” – time for a new nomenclature?

Abstract The endocrine cells of the gastrointestinal (GI) tract and the pancreas, referred to as the enteroendocrine cells, secrete a large variety of peptides and amines that regulate functions of the digestive tract itself and of distant organs. Taken together, the enteroendocrine cells form the largest system of endocrine cells in the body, presently comprising 16 cell types. Many of them have been named after letters of the alphabet, but the names are only occasionally related to morphological or functional characteristics of the cell. In this review of the normal, adult, mammalian enteroendocrine cells, we summarize synonyms, functions, locations, structure, stored hormones/amines, receptors, and other cellular expressions. We propose that the enteroendocrine cells should be renamed after their most well-known hormone/amine and, when applicable, their anatomical location, with opportunities for future revisions.