The dream of one day completely doing away with frustratingly long transplant lists in favor of made to order, 3D-printed organs is closer to becoming a reality. Scientists at Organovo in San Diego have, for the very first time, been able to 3D print tiny replicas of human livers.

At just half a millimeter deep and four millimeters across, the mini livers can perform most of the same functions as the larger version hanging out over your gallbladder. Which means that these presumably adorable bile-makers stand to serve a variety of purposes, the most immediate of which would be using them to observe how our livers react to certain drugs and diseases.

Scientists Have 3D-Printed Mini Human Livers for the First Time EverS

Current liver analyses are only able to last a few days, since they're based on just a few layers of cells that aren't even able to perform many of an actual livers' functions. These new mini livers, though, are great approximations of the real deal, producing the proteins that carry hormones and drugs throughout the body, cholestoral, and the major detoxification enzymes that let you consume reasonable amounts of alcohol without dying.

From here, Organovo plans to move on to the normal-sized organs that could be transplanted into real, live human bodies. Of course, they'd first have to solve the problem of how to print larger branches of blood vessel networks capable of nourishing an entire organ. But if these itty bitty livers are any indication, the real deal is well on its way. [New Scientist]