Perl’s reaction was performed in a 1:1 mixture of 20% potassium ferrocyanide and HCL. For KB staining, sections were incubated in 0.1% luxol fast blue MBS solution and counterstained in 0.1% cresyl violet acetate solution. For the TH immunohistochemical staining, the sections were incubated in the primary antibody (rabbit anti-tyrosine hydroxylase, AB152, Millipore Corporation, Temecula, CA) at a dilution of 1:500 in 1% normal goat serum, followed by biotinylated goat anti-rabbit immunoglobulin G (1:200 dilution). Immunohistochemical staining for calbindin D28K was performed using the rabbit anti-Calbindin D-28K (1:500 dilution, AB1778, Millipore Corporation, Temecula, CA) and biotinylated goat anti-rabbit immunoglobulin G (1:200 dilution). All slides were scanned using Olympus Slide virtual microscopy (Olympus, Japan) with a spatial resolution of 0.6836 μm2 per pixel (100×) and stored in lossless compression formats (Olympus virtual slide image format.vsi and JPEG 2000.jpx).