Fig. 2.

Subcellular distribution of m4R immunoreactivity in the striatum in the matrix and patches of control rats using the pre-embedding immunogold method with silver intensification. The matrix and patch areas were identified by the absence (A) or presence (B), respectively, of immunoreactivity for μ-opiate receptor (MOR), detected by the immunoperoxidase method. In B, the MOR immunoreaction product was visible close to the membrane of the cell body and in a dendrite (d). A,B,Immunopositive cell body with an unindented nucleus (n) and thin rim of cytoplasm are characteristic of striatal medium spiny neurons. The immunoparticles are associated mostly with the internal side of the plasma membrane (arrowheads). The density of immunoparticles is higher in the patches (B) than in the matrix neurons (A). Some immunoparticles are associated with the outer nuclear membrane (flat arrows) and the internal side of the membrane of dendrites (d). Scale bars, 0.5 μm. n, Nucleus.