The e-Mouse Atlas (EMA) is a detailed model of the developing mouse. Its purpose is not only to provide information about the shape, gross anatomy and detailed histological structure of the mouse, but also to provide a framework into which information about gene function can be mapped. The spatial, temporal and anatomical integration achieved by mapping diverse data to the organism itself rather than simply to database tables, allows powerful computational analyses. The website presents 3D volumetric models of the embryo linked, in most cases, to comprehensive and detailed images of histological structure. The embryo models and anatomy in EMA are organized by standard developmental stage (TS. after Theiler, 1989) and age of the embryo in days post coitum (dpc.). Gene-expression and other image data is also available.