title: Terminal Schwann cells participate in the competition underlying neuromuscular synapse elimination.
abstract: The competitive processes that result in elimination/pruning of developing synapses are incompletely understood. Serial electron microscopy was used to image postnatal mouse neuromuscular junctions where elimination is well studied and events at every synaptic contact can be examined. Glial or Schwann cells (SCs) are shown to have two activities during elimination: their processes separate nerve terminals from each other and from the muscle fiber; they contact the plaque of acetylcholine receptors, apposing this surface as closely as the nerve, limiting the area where synaptic transmission occurs. SCs phagocytose nerve terminals contacting the muscle fiber. This phagocytosis involves all axons; SCs are not selecting the winner but rather driving turnover. Previous modeling of stochastic turnover and reoccupation of nerve contacts shows that single innervation of synaptic sites can result. Thus, our study shows roles of SCs in neuromuscular development beyond the previous demonstration of consumption of synaptic inputs after their elimination.
authors.affiliation: Department of Biology and Institute for Neuroscience, Texas A&M University, College Station, Texas 77843 and Section of Molecular Cell and Developmental Biology, School of Biological Sciences, Institutes for Cell and Molecular Biology and Neuroscience, University of Texas at Austin, Austin, Texas 78712.
authors.forename: Ian W
authors.initials: IW
authors.lastname: Smith
authors.forename: Michelle
authors.initials: M
authors.lastname: Mikesh
authors.forename: Young il
authors.initials: Yi
authors.lastname: Lee
authors.forename: Wesley J
authors.initials: WJ
authors.lastname: Thompson
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D009469:Neuromuscular Junction / Q000502:physiology* / Q000648:ultrastructure; D011950:Receptors, Cholinergic / Q000502:physiology; D012583:Schwann Cells / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D011950:Receptors, Cholinergic