Striatal TH⁺ cell counts taken from animals infected with rAAV–MD–hTH 3 weeks and 6 months previously. The mean Abercrombie corrected TH⁺ cell counts (+ SEM) from animals processed 3 weeks after transduction with rAAV–MD–TH is represented by the black bar, and the mean corrected cell counts from rAAV-transduced animals allowed to survive 6 months is represented by the open bar. Theasterisk indicates a significant reduction of the number of TH⁺ cells at 6 months (p = 0.05).