Figure 3: Representative low-power photomicrographs of frontal brain sections stained for tyrosine hydroxylase (TH) showing the substantia nigra pars compacta (SNc), optic tract (OT), and a small part of the ventral tegmental area (VTA) of a control and a transgenic HD rat. Note the increased TH-containing cell density in the SNc of the transgenic HD rats upon close inspection. The high-power photomicrograph inset in the right upper corner shows a magnification of TH-containing cells of a transgenic rat. Scale bar is approximately 250  m. The anatomical level is approximately anteroposterior −5.2 mm from Bregma according to the Paxinos and Watson atlas of 1998. Adopted from Jahanshahi et al. [10].