TH and Parkinson disease: After 8-24 months, surviving grafted dopaminergic neurons exhibited neurite extension throughout the putamen and partially into the caudate head, with morphology and size resembling host substantia nigra neurons; most cells expressed FOXA2, 33.3 ± 24.4% co-expressed TH, and the average number of TH+ neurons was 64 ± 49 K per hemisphere, with no difference between healthy and PD-derived grafts; these TH+ cells also expressed DAT and GIRK2, and no 5-HT+ cells were observed due to CORIN-based cell sorting