Alpha-synuclein-positive neurons (A1) and varicosities (A2) are present in the ganglia of adult rats and easily differentiated from the markedly swollen alpha-synuclein-positive varicosities and axons observed in aged rats (A3). Dystrophic axons immunoreactive for either calretinin (B), calbindin (C), TH (D), or calcitonin gene-related peptide (CGRP; E) but negative for alpha-synuclein were found in the myenteric plexus of aged rats; the images in panels B-E come from whole mounts double labeled for alpha-synuclein (not shown). Focus stacking (6 images) was used for panel B. Scale bar in E = 25 μm for A1,A2,B-E; 50 μm for A3.