An inflammatory response is present but not detrimental to axon regeneration. (A) Longitudinal section through a wisping stage regenerate. Axons were labeled with 3A10 (magenta), nuclei are in blue, and fluorescent channels were laid over the phase image. (B) A section adjacent to (A) stained with H&E. Many small cells with dark blue nuclei are present near wisping axons. (B') Enlargement of blue box in (B). Lymphocytes (arrowhead) and monocytes (arrows) can be identified near wisping axons. (C-E) Longitudinal section through a wisping stage regenerate imaged with EM. (C) Region containing axons regenerating into the injury site. Many phagocytic cells (asterisks), or macrophages, can be identified near regenerating axons. (D) Enlargement of box D in (C). Processes from this macrophage (m) are in direct contact with regenerating axons (ax). (E) Enlargement of box E in (C). Another example of a meningeal cell-like process (p) that is mingled and closely associated with regenerating axons (ax). ecm, ECM; R, rostral; C, caudal. Scale bars: 200 μm (A, B); 50 μm (B',C); 5 μm (D); 1 μm (E).