using rapid ionic fixation with molybdic or tungstic heteropolyanions ( strong precipitating agents of quaternary ammonium cations such as choline and acetylcholine ) , acetylcholine-like cations were localized as point-like precipitates in the synaptic vesicles of resting ( electrically nonstimulated ) motor nerve terminals .
C0022023
ionic
C0007447
cations