(B-G) Munc18-1 null hippocampal neurons were rescued with wildtype Munc18-1a or a Munc18-1 mutant, Y473A, in which Y473 was replaced with alanine.(G) Typical electron microscopy images from rescued autaptic hippocampal Munc18-1 null neurons (scale bar = 100 nm). Neurons expressing M18Y473A have less synaptic vesicles (SV) docked at the number of docked SV. Average  