Figure 1.

Selective depletion of TH immunoreactivity in the pars compacta of the SN of Atm-deficient mice and a corresponding loss of TH-positive terminals in the striatum. (A) (Left) Low-power (×2.5) view of a coronal section through the lower diencephalon illustrating the region of the SN, ventral tegmental area (VTA), and the central gray (CG) where TH-positive cells were found. (Right) Cresyl violet-staining of the region of the SN, illustrating cell loss in the Atm-deficient brain (Left, control, Right, Atm-deficient, arrows point to SN pars compacta cells). (B) TH immunostaining of the region of the SN demonstrating a marked reduction in cell and fiber staining in the region of pars compacta (arrows). (C) High-power (×120) images of cells in the central gray (Upper) and SN (Lower) in control (Left) and Atm-deficient (Right) mice. Note the normal appearance of cells in the central gray and the lack of cell staining in the SN. (D) Low-power (×7) images of the striatum, stained for TH in normal (Left) and Atm-deficient (Right) mice. Note the difference in size of the two age-matched brains. (E) Low-power (×7) view of coronal sections through the striatum, stained for the dopamine transporter in control (Left) and Atm-deficient (Right) mice. A clear reduction in staining for the DAT is seen in the Atm-deficient mouse. (F) Staining of the nucleus locus coeruleus for TH at high power (×35) (Upper) and low power (×9) (Lower), illustrating that the noradrenergic nucleus is not affected in the Atm-deficient mouse. (G) The striatum of control (Left) and Atm-deficient (Right) mice, stained for acetylcholine esterase, demonstrating a lack of difference, despite the smaller size of the Atm-deficient brain.