Fig. 2

Cellular response to injury in Non-Regenerative Stage. a Cartoon depicting the process of spinal cord injury in NF stage 66. b Semithin section at 2 dpt. c, d; f-g; i-l; n-p Correspond to ultrathin sections observed by transmission electron microscopy. c, d Different regions of the spinal cord at 2 dpt; c central canal (cc) next to the injured site (black arrowheads); d extracellular matrix and red blood cells (red shadow) in the injury site. e Semithin section at 6 dpt. f, g Different regions of the spinal cord at 6 dpt; f ependymal cells in the rostral stump (black arrowheads); g macrophage (blue line) engulfing red blood cells (red shadow) in the cc. h Semithin section of the caudal stump at 10 dpt. i-l Different regions of the spinal cord at 10 dpt; i ependymal cells near to the injured site; j mitochondria (white arrowhead) in the apical surface of ependymal cell (blue line) in contact with the cc; k glial cell processes next to the injured site (white arrowheads); l intermediate filaments (white arrowheads) in the glial process (green line). m Semithin section at 20 dpt. n-p Different regions of the spinal cord at 20 dpt; n ablation gap (red lines) filled with fibroblast-like cell (white arrowhead), and surrounded by extracellular matrix; o microglial-like cell (cyan line) with abundant rough endoplasmic reticulum (white arrowheads); p abundant Collagen (col) fibers (dots) in the injured site. The red dotted lines indicate the injured site (a, b, e, h, m)