The colorful snakelike image above is actually fluorescently labeled tissue from a section of a stomach that’s smaller than a pea. But it’s not the stomach of an extraordinarily small animal; it’s a mini human stomach grown in a dish by scientists who hope to use it to study gastrointestinal diseases. Because the digestive systems of mice, flies, and other model organisms differ from those of humans, researchers have been hard-pressed to find a way to study the development of human gut maladies such as peptic ulcer disease. So several groups have turned to pluripotent stem cells—cells derived from human embryos or reprogrammed adult cells that can turn into any cell type in the body—to try to grow digestive organs in the lab. Last week, one group of researchers announced the creation of a lab-grown small intestine from stem cells. Today, a different team reports online in Nature that they’ve perfected the recipe of molecules needed to coax both types of stem cells to grow into small spheres that, despite their size, have all the properties of a functional stomach. When the researchers exposed the ministomachs to the bacterium Helicobacter pylori, infections of which are blamed for many stomach ulcers and cancers, they saw the same molecular and cellular changes already known to occur in life-size stomachs.