Fig 4. Most threads are located in the peri-axonal space.

(A) Micrographs showing high magnification of sagittal spinal sections co-labeled with AB42 (red), neurofilament (blue) and myelin basic protein (A1-2; green) or CNPase (A3; green). The majority of threads are confined within the myelin cylinder. A thread coiled into a knot-like structure is visible in A1. A2 shows a long and slender thread running in parallel with an axon. Occasionally, threads are found outside myelin (arrowheads in A2 and 3). A3 shows part of the thread presumably inside the axon and part of it outside (arrowhead) and it appears to pass through an opening in the myelin (arrow and insert). (B) Cross-sectional images depicting threads outside (B1), inside (B2), and surrounding (B3) axons, as well as piercing through the myelin sheath (B4). (C) z-stack image depicting a thread (green, intersected lines) lying outside an axon (red). Scale bar in A1-A2 = 25μm; A3 = 10μm; B1-3 = 10μm in length; C = 10μm.