Higher magnification EM images of VGLUT1+ immunolabeled synaptic terminals on spines of striatal projection neurons in striatum of 1 month- (A, B), 4 month- (C, D), and 12 month-old (E, F) wildtype (A, C, E) and heterozygous Q140 Huntington knock-in (B, D, F) mice. Spines (Sp) were recognizable by their small size, the presence of spine apparatus, and the absence of mitochondria and microtubules. All VGLUT1+ synaptic terminals formed asymmetric synaptic contacts, as recognizable by the thick postsynaptic density (PSD, arrow). All images are at the same magnification.