Figure 2.

D₁ and D₂ MSNs receive synaptic input from VGluT1-positive terminals and VGluT2-positive terminals. A, A spine (sp) of a D₁ MSN, identified by peroxidase immunolabeling for EGFP, receiving asymmetric synaptic input (arrowhead) from a VGluT1-positive terminal (t), identified by immunogold labeling. Note the large crystal-like reaction product formed by TMB. B, A spine (sp) of a D₁ MSN, identified by immunoperoxidase labeling for EGFP, receiving asymmetric synaptic input (arrowhead) from a VGluT2-positive terminal (t), identified by immunogold labeling. Note the floccular electron dense peroxidase reaction product. C, A spine (sp) of a D₂ MSN identified by peroxidase labeling for EGFP receiving asymmetric synaptic input (arrowhead) from a VGluT1-positive terminal (t) identified by immunogold labeling. Note the large crystal-like reaction product formed by TMB. D, A spine (sp) of D₂ MSN, identified by peroxidase labeling for EGFP, receiving asymmetric synaptic input (arrowheads) from a VGluT2-positive terminal (t) identified by immunogold labeling. Note the large crystal-like reaction product formed by TMB. Scale bars, 250 nm.