A-B. FRIL electromicrographs at low magnification showing the IMP-cluster
distribution of auditory nerve synapses (AN) on bushy cell soma (A) and on
basal dendrites of fusiform cells (B). B' shows higher magnification
of the boxed area in B. The IMP-clusters are pseudocolored in blue to aid visualization.
C-D. Images of PSDs of AN synapses on the cell body of a BC
(C) and on a basal dendrite of a FC (D) immunolabeled with
N-terminus antibodies for pan-AMPAR (GluA1-4) antibody (5 nm gold; C) or
GluN1 (5 nm gold; D), indicating the presence of IMP-clusters on the E-face,
accompanied by a presynaptic protoplasmic face (P-face) that was labeled by vGluT1
immunoparticles (vesicular glutamate transporter 1; 10 nm gold) as a marker for AN
endings. Scale bars: A: 1 μm, B: 2 μm, B': 500 nm, C-D: 200
nm.