Pruning of axonal trees results in increased efficacy of surviving nerve terminals.

The intramuscular nerve was crushed in mouse tensor fascia latae muscles so that on average motor units lost 40% of their terminals. Quantal contents at 20% of the surviving terminals had doubled in muscles examined between 17 h and 9 days later. Silver staining revealed that some surviving nerve terminals had sprouted, but too few to account for the quantal content increases. Redistribution of axoplasmically transported materials to the surviving terminals is hypothesized to explain the increase in their efficacy.