Dual Immunostaining of Na+/K+ ATPase αIII and dystrophic neurites. Horizontal sections were immunostained for Na+/K+ ATPase using DAB with nickel intensification followed by Congo red staining for Aβ plaques. A discernable circumferential void in ATPase staining surrounding the plaque was observed (Panel A, scale bar = 50 μm; Panel B, scale bar = 16.67 μm). Immunofluorescent staining of dystrophic neurites using the anti-phosphorylated neurofilament antibody SMI-312 followed by Congo red staining demonstrate a close relationship between amyloid plaques and dystrophic neurites (Panel C; white arrows demarcate the neurites). Congo red yellow fluorescence was digitally suppressed to more clearly reveal the green-stained neurites (scale bar = 16.67 μm). Panel D is a digital overlay of the fluorescein-labeled dystrophic neurite image onto the bright field peroxidase-labeled Na+/K+ ATPase + Congo red image which demonstrates that dystrophic neurites are present predominantly in the zone devoid of Na+/K+ ATPase staining surrounding the congophilic plaques (scale bar = 16.67 μm).