Quantifying dystrophic features. PGP-9.5 and 4-HNE co-stained neurons were classified into different categories, according to the degree of dystrophy, as defined by certain morphological features. Non-dystrophic neurons had a normal appearance, with smooth and intact processes (AI-III). Mildly dystrophic neurons exhibited some features of dystrophy, such as outgrowths of lamellipodia-like structures from cell bodies and proximal neurites (arrows, BI), and sharp angles in neuronal processes (arrows, BII and III). Highly dystrophic neurons demonstrated irregular morphological features, such as aberrant neuritic growth from cell bodies and the appearance of frequent loops and curls in neuritic processes (arrows, CI-III).