Micrographs of the SN of (A) Air and (B) CAPs exposed Apo E -/- mouse brain and representative examples of the nucleus compacta which house the dopaminergic neurons, vulnerable to OS. Sections were taken from the same brain level. Neurons and astrocytes were immunocytochemical stained with TH and GFAP, respectively. A 29% reduction of TH staining and an 8% increase in GFAP was measured in the Apo E-/- PM exposed mice relative to air exposed Apo E-/- No differences in TH or GFAP bodies were observed in C57 Air or PM exposed animals. Sections 300× magnification.