Fig. 8. Schematic illustration of the proposed molecular mechanism for the morphology switch. The arrows indicate hydrolysis (1), nucleation (2) and fibril elongation (3). At low starting concentration, hydrolysis results in peptide fragments with a length distribution that, on average, is shorter than at high concentrations. This affects the structure of the fibril nuclei as longer peptide segments will be included and the C-terminal core segment will be incorporated to a higher degree at higher starting concentrations.