Evidence for a postnatal elimination of terminal arborizations and synaptic boutons of recurrent motor axon collaterals in the cat.

Triceps surae alpha motoneurons in cats of different postnatal ages were stained intracellularly with horseradish peroxidase (HRP). The recurrent axon collateral trees of the neurons were studied light microscopically. A large reduction of the number of axon collateral end branches and swellings, interpreted as synaptic boutons, was found to occur during the first two weeks of postnatal life.