Fig. 2.

PV-PIIs express mGluR1α and mGluR5. Confocal images of the DG showing immunofluorescent labeling for PV (red), mGluR1α (A, white), and mGluR5 (B, green) in somata (Left) and basal dendrites (Right). gcl, granule cell layer. Electron micrographs show dendritic profiles in the DG hilus with immunogold labeling of PV and immunoperoxidase labeling of mGluR1α (C, asterisks) and mGluR5 (D, asterisks). (C and D, Right) Regions indicated by dashed lines are shown. Note that islets of peroxidase reaction product (asterisks) are located close to asymmetrical, putative MF synapses (arrows). (E) Electron micrograph shows immunoreactivity for mGluR5 (Right; immunogold, arrowheads) in a PV⁺ dendrite (Left; peroxidase reaction end product, asterisks). (F) Three-dimensional reconstruction of a PV⁺ dendrite from 42 consecutive ultrathin sections showing peri- and extrasynaptic location of mGluR5 immunogold labeling (black dots) relative to PSDs (red areas) of asymmetrical synapses. Arrows point to the plane of the section shown in E. (G) Distribution of mGluR5 immunoparticles (n = 453) on PV⁺ basal dendrites (n = 7) relative to the edges of the nearest PSD of an asymmetrical synapse. Bin size = 60 nm.