TY - JOUR
T1 - Pervasive Synaptic Branch Removal in the Mammalian Neuromuscular System at Birth
AU - Tapia, Juan C.
AU - Wylie, John D.
AU - Kasthuri, Narayanan
AU - Hayworth, Kenneth J.
AU - Schalek, Richard
AU - Berger, Daniel R.
AU - Guatimosim, Cristina
AU - Seung, Hyunjune Sebastian
AU - Lichtman, Jeff W.
N1 - Funding Information:
This work was supported by grants from the National Institutes of Health, the Gatsby Charitable Trust, and the Center for Brain Science, Harvard University. J.D.W. was supported by Medical Scientist Traineeship, Washington University, St. Louis. C.G. was supported by IBRO and Conselho Nacional de Pesquisa.
PY - 2012/6/7
Y1 - 2012/6/7
N2 - Using light and serial electron microscopy, we show profound refinements in motor axonal branching and synaptic connectivity before and after birth. Embryonic axons become maximally connected just before birth when they innervate ∼10-fold more muscle fibers than in maturity. In some developing muscles, axons innervate almost every muscle fiber. At birth, each neuromuscular junction is coinnervated by approximately ten highly intermingled axons (versus one in adults). Extensive die off of terminal branches occurs during the first several postnatal days, leading to much sparser arbors that still span the same territory. Despite the extensive pruning, total axoplasm per neuron increases as axons elongate, thicken, and add more synaptic release sites on their remaining targets. Motor axons therefore initially establish weak connections with nearly all available postsynaptic targets but, beginning at birth, massively redistribute synaptic resources, concentrating many more synaptic sites on many fewer muscle fibers. Analogous changes in connectivity may occur in the CNS.
AB - Using light and serial electron microscopy, we show profound refinements in motor axonal branching and synaptic connectivity before and after birth. Embryonic axons become maximally connected just before birth when they innervate ∼10-fold more muscle fibers than in maturity. In some developing muscles, axons innervate almost every muscle fiber. At birth, each neuromuscular junction is coinnervated by approximately ten highly intermingled axons (versus one in adults). Extensive die off of terminal branches occurs during the first several postnatal days, leading to much sparser arbors that still span the same territory. Despite the extensive pruning, total axoplasm per neuron increases as axons elongate, thicken, and add more synaptic release sites on their remaining targets. Motor axons therefore initially establish weak connections with nearly all available postsynaptic targets but, beginning at birth, massively redistribute synaptic resources, concentrating many more synaptic sites on many fewer muscle fibers. Analogous changes in connectivity may occur in the CNS.
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U2 - 10.1016/j.neuron.2012.04.017
DO - 10.1016/j.neuron.2012.04.017
M3 - Article
C2 - 22681687
AN - SCOPUS:84861925555
SN - 0896-6273
VL - 74
SP - 816
EP - 829
JO - Neuron
JF - Neuron
IS - 5
ER -