Narrowings of the synaptic cleft in myoneural junctions.
D000818:Animals; D002645:Chickens; D008854:Microscopy, Electron; D009469:Neuromuscular Junction / Q000033:anatomy & histology*; D009801:Oculomotor Muscles / Q000166:cytology; D051381:Rats; D013569:Synapses / Q000166:cytology*