Through a coordinated application of growth factors, Dr. Wells and colleagues have developed a technology to mimic embryonic intestinal development in vitro, resulting in the formation of three dimensional organoid structures. These organoids consist of a polarized, columnar epithelium patterned into villus-like structures and crypt-like proliferative zones expressing intestinal stem cell markers. This technology provides a unique platform for the pre-clinical testing of intestinal therapies, and the effects of pharmaceuticals on cells of the gastrointestinal tract.