Multiple Innervation (IMAGE) Princeton University Caption Princeton University researchers found that proteins in the MHCI, or major histocompatibility complex class I, family may contribute to fine-tuning a person's motor control as they grow -- and also contribute to their gradual loss of muscle function as they age. They found that MHCI proteins "prune" the connections, or synapses, between motor neurons and muscle fibers, which is necessary during early development. This image from a mouse bred to express less MHCI shows two motor neurons (green) still connected to a single muscle fiber (red) at an age when only one connection should remain. Credit Image by Lisa Boulanger, Princeton Neuroscience Institute, and Mazell Tetruashvily, Department of Molecular Biology Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.