Organization of the injured RNC during the early post-injury phase (days 1 – 2). (A) Lesioned radial organ complex as viewed from the coelomic side of the body wall. (B – F) Longitudinal sections through the RNC. (B) Low-magnification view of the wound region; hematoxylin and esosin staining. (C) In the vicinity of the wound, the radial glial cells (magenta) still retain RS-like immunoreactivity (green) in the apical region of the ectoneural neuroepithelium. The dashed line shows the outlines of the cut end of the RNC. (D) Double labeling with the glial marker ERG1 (magenta) and the neuronal marker anti-GFSKLYFamide antiserum (green). (D’) and (D”) show these two types of labeling in separate channels. (E) Fragmentation (arrowheads) of glial processes (magenta) in the vicinity of the wound. (F) Neuronal processes (green) in injury area exhibit bulbous terminal swelling (arrow). bw, body wall connective tissue; c, coelom; ec, epineural canal; en, ectoneural neuroepithelium; hn, hyponeural neuroepithelium; rnc, radial nerve cord; roc, radial organ complex; wg, wound gap; wvc, water-vascular canal. Asterisk in (C, D, D’) indicates the zone of dedifferentiation in the ectoneural neuroepithelium with the radial glial cells preserving epithelial organization.