Fig. 7.

Electron microscopic immunogold localization of the Kv4.2 and Kv4.3 subunits in the glomerular layer. (A) Clusters of immunogold particles for the Kv4.2 subunit (filled arrowheads) are shown along the somatic plasma membrane of an external tufted cell (ETC) that is in direct contact with a periglomerular cell (PGC). Part of the plasma membrane that faces the neuropil (open arrowheads) is not labeled. (B) A high magnification view of an immunopositive cluster (filled arrowheads) on an ETC soma reveals that the gold particles are enriched in a membrane specialization. (C and D) Glial processes wrapping mitral/tufted cell dendrites (MCd) are labeled for the Kv4.2 subunit (filled arrowheads). A low density of labeling (open arrowheads) is found on the plasma membrane of mitral/tufted cell dendrites (MCd), which form synapses in the glomerulus (arrows). (E) Strong immunogold labeling for Kv4.3 subunit is seen in a process enwrapping the soma of a periglomerular cell (PGC). The density of the gold particles is much higher along the membrane (filled arrowheads) that touches the PGC soma than that contacting the surrounding neuropil (open arrowheads). (F) A Kv4.3 subunit immunopositive process forms a thin sheet around a PGC. (G and H) Kv4.3 subunit positive clusters are observed on dendrites (d) in the glomerulus, which receive asymmetrical synapses (filled arrowhead) from other dendrites. Scale bars: 0.5 μm (A, C, E, G and H); 0.3 μm (B, D and F).