Nerve terminals are as metabolically different as the muscle fibers they innervate

Science ◽  
1980 ◽  
Vol 210 (4472) ◽  
pp. 927-928 ◽  
Author(s):  
J. Pickett
1997 ◽  
Vol 78 (6) ◽  
pp. 3498-3501 ◽  
Author(s):  
Joanne Pearce ◽  
Kristin M. Krause ◽  
C. K. Govind

Pearce, Joanne, Kristin M. Krause, and C. K. Govind. Muscle fibers in regenerating crayfish motor nerves. J. Neurophysiol. 78: 3498–3501, 1997. Single discrete muscle fibers were found in regenerating motor nerves in adult crayfish. The regenerating nerves were from native or transplanted ganglia in the third abdominal segments and consisted of several motor axons. The proximal end of these motor axons showed numerous sprouts. Muscle fibers in these regenerating nerves appeared newly developed and were innervated by excitatory nerve terminals. A likely source of these novel muscle fibers may be blood cells in the nerve or satellite cells from neighboring muscle. Contacts made by axon sprouts with other axon sprouts, glia, and muscle fiber, in the form of a dense bar with clustered clear vesicles, characterized the regenerating nerve. These contacts may provide a possible signaling pathway for axon regeneration and myogenesis.


1978 ◽  
Vol 78 (1) ◽  
pp. 176-198 ◽  
Author(s):  
J R Sanes ◽  
L M Marshall ◽  
U J McMahan

Axons regenerate to reinnervate denervated skeletal muscle fibers precisely at original synaptic sites, and they differentiate into nerve terminals where they contact muscle fibers. The aim of this study was to determine the location of factors that influence the growth and differentiation of the regenerating axons. We damaged and denervated frog muscles, causing myofibers and nerve terminals to degenerate, and then irradiated the animals to prevent regeneration of myofibers. The sheath of basal lamina (BL) that surrounds each myofiber survives these treatments, and original synaptic sites on BL can be recognized by several histological criteria after nerve terminals and muscle cells have been completely removed. Axons regenerate into the region of damage within 2 wk. They contact surviving BL almost exclusively at original synaptic sites; thus, factors that guide the axon's growth are present at synaptic sites and stably maintained outside of the myofiber. Portions of axons that contact the BL acquire active zones and accumulations of synaptic vesicles; thus by morphological criteria they differentiate into nerve terminals even though their postsynaptic targets, the myofibers, are absent. Within the terminals, the synaptic organelles line up opposite periodic specializations in the myofiber's BL, demonstrating that components associated with the BL play a role in organizing the differentiation of the nerve terminal.


1973 ◽  
Vol 146 (2) ◽  
pp. 155-165 ◽  
Author(s):  
H. L. Atwood ◽  
C. K. Govind ◽  
G. D. Bittner

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