(B) Confocal microscopy images of WT and MPS-IIIA hippocampal neurons (DIV14) double labeled with anti-synapsin-1 (presynaptic marker; red) and either anti-VAMP2 or anti-SNAP25 antibodies (green). The merges (yellow) of confocal images are shown. SNAP25-synapsin-1 and VAMP2-synapsin-1 co-localizations were quantified using the Manders' Colocalization Coefficients (MCC) (ImageJ) and displayed as % (MCC x 100) of Synapsin-1 co-localizing with either SNAP25 or VAMP2 (means ± s.e.m. from 15 different images taken from 4-5 coverslips for each group). 