Comparison of morphology and physiology of synapses formed at ectopic and original endplate sites in frog muscle.
The properties of junctions formed de novo in ectopic regions of muscle were studied and compared to those of endplates reinnervated after nerve crush and to normals. The nerve to the frog cutaneous pectoris muscle was transposed and implanted onto an endplate-free (ectopic) region of that muscle, while the endplate-containing portion was excised. New synapses, which subsequently formed in the remaining muscle segment, were studied morphologically and physiologically at postoperative times from approximately 3 weeks to a year. Junctions formed de novo consisted of numerous small contacts, and were only 15% as long as those in control groups. Yet, quantal contents were 2.5-4.7 times larger at de novo junctions.
D000818:Animals; D001369:Axons / Q000648:ultrastructure; D005071:Evoked Potentials; D008854:Microscopy, Electron; D009045:Motor Endplate / Q000502:physiology* / Q000648:ultrastructure; D009409:Nerve Crush; D009416:Nerve Regeneration; D009469:Neuromuscular Junction / Q000502:physiology* / Q000648:ultrastructure; D010369:Pectoralis Muscles / Q000294:innervation*; D011894:Rana pipiens; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission