No organ left behind: tales of gut development and evolution.

The function of an organ is dependent on its cellular constituents as well as on their assembly into a cohesive unit. The developing gut faces unique challenges as one of the longest and largest organs in the body and also because it is constantly interfacing with external factors through the diet. Its location deep within the body has until recently hampered investigation into its formation. The patterning of the gut along its longitudinal, dorsoventral, left-right, and radial axes is one of the fascinating issues that pertain to the development, function, and homeostasis of this understudied organ.