Developmental relationships between opiate receptors and dopamine in the formation of caudate-putamen patches.

Opiate receptor distribution changes from a diffuse to a patchy pattern in the perinatal rat caudate-putamen. The opiate receptor patches are continuous with the patches of dopamine fluorescence seen in the perinatal striatum. Both types of patches match areas of relatively low neuronal cell density as seen in Nissl-stained sections. Neither embryonic haloperidol nor embryonic naloxone treatment blocks the formation of opiate receptor patches.