The colorful snakelike image here is fluorescently labeled tissue from a stomach smaller than a pea. But the organ is not from a very small animal; it’s a mini human stomach grown in a dish. The digestive systems of mice, flies, and other model organisms differ from those of humans, making them of limited use for studying human gut diseases. So researchers have turned to pluripotent stem cells—cells derived from embryos or reprogrammed adult cells that can potentially turn into any cell type—to grow digestive organs in the lab. Last week in Nature Medicine, one group unveiled a small intestine created from human stem cells. This week, a different team reports in Nature that they’ve coaxed both types of stem cells to form small spheres with all the properties of a functional stomach. When the researchers exposed the tiny stomachs to the bacterium Helicobacter pylori, which contributes to stomach ulcers and cancers, they saw the same cellular changes known to occur in life-size stomachs.