Fig. 5.

Photomicrographs showing Lucifer yellow-labeled spiny cells identified in the accumbens core (A) and shell (B) region. In control rats, most injections of individual cells with Lucifer yellow resulted in single-cell labeling of spiny neurons. A, A single Lucifer yellow-labeled spiny neuron (A1, arrow) that was converted into a peroxidase stain using Lucifer yellow antibodies (A2). This cell was subsequently identified in the accumbens core region (A3, arrow), as delineated by the calbindin-positive neuropil (presence of Texas Red fluorescence). Spiny neurons in the core region tended to have more widespread dendritic processes than those recovered in the shell region. B, A single Lucifer yellow-labeled spiny neuron (B1, arrow) in which the fluorescence was converted into a peroxidase stain (B2, arrow). This neuron was located in the accumbens shell region as outlined by the negative staining for calbindin immunoreactivity (B3, absence of Texas Red fluorescence). The axon of this cell (B1, asterisk) was traced into the ventral pallidum where numerous collaterals were emitted (B4, low power; B5, high power). The three highlighted arrows withasterisks in B4 show collaterals of the primary axon. The solid arrows in B4 andB5 mark the same axonal collateral. bv,Blood vessel (in B4 and B5 indicating the same structure); VS, ventral striatum;VP, ventral pallidum; ac, anterior commissure; cc, corpus callosum. Scale bars, 30 μm.A2 and A3 are at the same scale asA1; B3 is at the same scale asB2.