Figure 3.

D₁Rs in PV (diffuse precipitate) cellular profiles. A, PV perikarya display D₁Rs in association with endomembranes, whereas only a fraction is expressed on the plasmalemma (arrow). B, Similarly, in PV dendrites (den), D₁Rs may appear intracellularly and on nonsynaptic membranes (arrows). Note a second D₁R-immunoreactive dendrite shown to the bottom right in B. C, A PV varicosity (double arrowheads point to synaptic vesicles) lies next to an e-l bouton [axon 1 (ax1)] forming a synapse with perforated postsynaptic density (between arrowheads). Unlike the PV axon, ax1 and neighboring ax2 show perisynaptic and extrasynaptic D₁R labeling (arrows). Two other synaptic pairs also express D₁Rs. mit, Mitochondrion; lys, lysosome; sp, spine. Scale bars, 400 nm.