Exogenous NMDA accelerates removal of excess innervation. Left, Examples of multiply innervated (asterisks) and singly innervated end plates in control and NMDA-treated muscles at P8. Scale bar, 50 μm. Right, NMDA-treated muscles at P8 had significantly fewer multiply innervated fibers than control. Open symbols indicate control; filled symbols, treated (EDL: 48 ± 2%, control limb vs 38 ± 4% vs NMDA-treated limb, p = 0.05, n = 8, 9; soleus: 63 ± 2%, control limb vs 49 ± 4%, NMDA-treated limb, p = 0.014, n = 7, 8).