Figure 1. Ammonia induces axonal degeneration of cultured neurons. (A) Axonal beading and fragmentation in the course of degeneration induced by ammonia (1, 2, 5, and 10 mM for 24 h) in cerebellar granule neurons (CGNs) cultured for DIV 7. Morphological changes of neurons were monitored with phase-contrast microscopy, and representative and enlarged images were shown. White arrows show the beading formation. Scale bar, 50 μm. (B) Same treated neurons were subjected to immunocytochemistry with MAP2 staining (Green signal) for dendrites and βIII-Tubulin (red signal) for neurites. Hoechst staining shows the nucleus of neurons. Whiter arrows show the beading formation along the axonal shafts. Dendrites revealed by MAP2 showed no varicosities. Scale bar, 20 μm. Quantitative measurements of neurite fragmentation (C) and axonal beading (D). Relative percentages in the control group (Ctrl) were set at 100% in (C).* p < 0.05 vs. Ctrl.