Neurons expressing M18Y473D are not impaired at SV docking. Autaptic munc18-1 null hippocampal neurons expressing M18Y473D or M18WT as controls were analysed with electron microscopy on chemically fixed samples (D) The active zone (AZ) length is similar (M18WT: 561 ± 24 nm; M18Y473D: 646 ± 59 nm, multilevel analysis, p = 0.161).(B-E) M18WT : N=6 autaptic neurons, n=137 synapses; M18Y473D: N=8 autaptic neurons, n=116 synapses. 