Photomicrographs demonstrating c-Fos-immunopositive cells in the GP (A, B), EP (C), SNR (D), and STN (E) ipsilateral to nigrostriatal lesions after systemic injections of apomorphine. In animals with unilateral nigrostriatal lesions, the numbers of c-Fos-positive cells are increased in the GP (A) and STN (E) ipsilateral to the lesion after systemic apomorphine. No differences in the c-Fos cell numbers between the lesioned and intact sides are seen in the EP (C) or SNR (D). The apomorphine-induced enhancement of c-Fos expression in the GP (B) is attenuated in the lesioned rats with nigral grafts. Scale bar, 100 μm.