Fig. 4

In vivo myelin disruption/dismantling and debris scavenging in CD47-deleted and wild type Schwann cells. Representative micrographs of cross sections from (A) intact and (B) through (F) Wallerian degenerating nerves taken 5 to 6 mm distal to but not including lesion sites on days 2 to 2.5 after surgery. A In CD47−/− mice, the flat myelin sheath forms tightly laminated spiral windings around intact axons. B through F In Wallerian degenerating nerves in CD47−/− mice, sections of tight laminated spiral windings loosen/unwind, exposing spaces between layers (B, C and D), forming small myelin coils of which some remain attached and some detach from large myelin spirals (E), and other become internalized into Schwann cells (F). Notably, microtubules and neurofilaments enrich the cytoplasm of intact axons (A), disrupted amorphous axonal cytoplasm embeds unwounded sections of myelin spirals (B, C, D and E), and numerous mitochondria enrich Schwann cells’ cytoplasm that embeds myelin debris (F). G and H Lower power micrographs of Wallerian degenerating nerves taken from (G) CD47−/− and (H) wild type mice. Bars: A, C, E and F 1 µm; B 2 µm; D 0.5 µm; G and H 10 µm