Figure 2

Transmission electron microscopy (TEM) micrographs of the transthyretin fibrillation process.
Already after 9 minutes small curvilinear protofibrils are revealed, apparently protruding between some spherical aggregates. These fibrillar structures, having a diameter of 5–10 nm are the most dominant species present throughout the fibrillation process. Mature fibrils formed in 10 mM HCl and 10 mM NaCl at 22 °C for >one month are also shown. The red filled arrows point at elongated protofibrils and the yellow arrow heads on annules, i.e. circular protofibrils. The scale bars represent 200 nm.