Enteroendocrine cells are cells found in the wall of the gut that secrete hormones that regulate numerous processes in the body, including controlling glucose levels, food intake, and stomach emptying. There are at least ten types of enteroendocrine cell and it has been hard to determine the exact role of each cell type and hormone they secrete because many of the hormones have partially overlapping functions. However, researchers have now generated mice lacking all enteroendocrine cells and hormones by deleting the gene Ngn3 and found that a lack of these cells leads to a high chance of dying during the first week of life.