Authors: Jonna Hamilton Richard M Dillaman Mary Kate Worden
Publish Date: 2006/06/21
Volume: 326, Issue: 3, Pages: 823-834
Abstract
The crustacean dactyl opener neuromuscular system has been studied extensively as a model system that exhibits several forms of synaptic plasticity We report the ultrastructural features of the synapses on dactyl opener of the lobster Homarus americanus as determined by examination of serial thin sections Several innervation sites supplied by an inhibitory motoneuron have been observed without nearby excitatory innervation indicating that excitatory and inhibitory inputs to the muscle are not always closely matched The ultrastructural features of the lobster synapses are generally similar to those described previously for the homologous crayfish muscle with one major distinction few dense bars are seen at the presynaptic membranes of these lobster synapses The majority of the lobster neuromuscular synapses lack dense bars altogether and the mean number of dense bars per synapse is relatively low In view of the finding that the physiology of the lobster dactyl opener synapses is similar to that reported for crayfish these ultrastructural observations suggest that the structural complexity of the synapses may not be a critical factor determining synaptic plasticityThe authors gratefully acknowledge the help of D Mark Gay with tissue preparation and imaging Charlie Hubbard with electron microscopy and Bette Dzamba and Douglas DeSimone with imaging We also thank DeForest Mellon for comments on the manuscript
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