Comparative distribution of MOR-immunoreactivity at different levels of coronal sections of the rat neostriatum (St): coronal sections stained with anti-MOR and GDN method arranged in a rostrocaudal order. A: MOR-immunoreactivity was localized in densely stained patches (arrows) and the subcallosal streak (arrowheads) at the rostral part of the St. Patches of MOR-immunoreactivity was most prominent in the rostral, dorsal portion of the neostriatum, which distributed irregularly, exhibiting complex and tortuous fields with multiple extensions. B: At the rostromedial portion of the St, the number of the patches decreased and the staining of MOR-immunoreactivity in the MrD was seen in a moon shape band that parallels with the subcallosal streak. C: At the caudomedial portion of the St, MOR-immunoreactivity was seen densely stained in the band of nerve fibers that arranged in parallels in the MrD. All scale bars: 500 um.